Routine antenatal care (BMJ) by Grainne Flannelly

Routine antenatal care

The right clinical information, right where it's needed

Last updated: Feb 07, 2019

Table of Contents Overview

Introduction

Pre-conception care

Antenatal care

Routine testing

Additional tests to consider

Ultrasonography

Screening for genetic abnormalities

Screening for neural tube defects (NTDs)

Screening for gestational diabetes mellitus

Screening for group B Streptococcus (GBS)

Rho D immune globulin administration

Diagnosis and treatment of anaemia in pregnancy

Management of post-term pregnancy

Obesity

Guidelines

Online resources

References

Images

Disclaimer

Routine antenatal care

Overview

Introduction

Pre-conception care Ideally, antenatal care begins before conception. Pre-conception care has been defined as a set of interventions to identify and modify biomedical, behavioural, and psychosocial risks to a woman's health or pregnancy outcome through prevention and management. Pre-conception care should be considered not as a single visit, but as a continuum of care throughout a woman's reproductive life.[1] Because a significant proportion of pregnancies are unintended, the negative consequences of many behaviours, illnesses, and medications can affect fetal development early in pregnancy; often damage to the fetus occurs before a woman even realises that she is pregnant. Thus, all routine healthcare encounters during a woman's reproductive years should include counselling on medical care and healthy behaviours to optimise pregnancy outcome.[1] [2] For example, healthy women should begin folic acid supplementation (400 micrograms/day), ideally at least 3 months before conception and continue until at least 12 weeks' gestation.[1] [3] [4] Factors affecting pregnancy outcome should include consideration of family history, genetic history, nutritional status, folic acid intake, environmental and occupational exposures, and teratogens. A history of illicit substance use, tobacco and alcohol consumption, medical conditions, medication, immunisation status, risk factors for sexually transmitted infections (STIs), psychosocial concerns (depression, domestic violence), and pregnancy spacing is required. For example, women with diabetes should be counselled on optimising glycaemic control, and pregnancy should be discouraged until control is achieved. [International Diabetes Federation: global guideline on pregnancy and diabetes] Immunisations for rubella, varicella, or hepatitis B should be offered to non-pregnant women who are susceptible, and women should avoid pregnancy for 1 month after receiving a live attenuated vaccine (e.g., rubella or varicella), even though the evidence does not suggest that they are in fact harmful.[5] [6] [CDC: guidelines for vaccinating pregnant women]

Antenatal care Early and regular antenatal care is recommended to improve pregnancy outcomes. Recommendations include antenatal visits, nutritional care, education, and other patient-specific issues. Antenatal visits • Traditional antenatal care includes a series of between 7 and 11 visits; however, the number of visits necessary for adequate care is disputed. Though limited data are available regarding the optimal frequency, timing, and content of visits, the number of antenatal care visits should be determined according to the needs and risk status of each woman and her fetus. In addition to scheduled routine visits, pregnant women should have access to unscheduled or emergency visits on a 24-hour basis. In the UK, 10 visits for an uncomplicated nulliparous woman and 7 for an uncomplicated parous woman are recommended.[7] • It is recommended that pregnant women initiate antenatal care by 10 to 12 weeks' gestational age.[8] The first antenatal visit should include a comprehensive history, laboratory work, and education about pregnancy health. Height and weight should be recorded to calculate body mass index (BMI), which provides information to determine weight gain guidelines. Structured records assist in ensuring comprehensive, evidence-based care.[9] • A comprehensive physical examination should be performed at the first or second visit.

This PDF of the BMJ Best Practice topic is based on the web version that was last updated: Feb 07, 2019. BMJ Best Practice topics are regularly updated and the most recent version of the topics can be found on bestpractice.bmj.com . Use of this content is subject to our disclaimer. © BMJ Publishing Group Ltd 2020. All rights reserved.

OVERVIEW

Antenatal care is a key component of a healthy pregnancy. Regular antenatal care helps to identify and treat complications and to promote healthy behaviours. Although there is little direct evidence, outcome data suggest that neonates born to mothers who do not receive antenatal care are 3 times more likely to be of low birth weight, and 5 times more likely to die, compared with neonates born to mothers who receive antenatal care. [US Department of Health and Human Services: prenatal care fact sheet] In addition to medical care, antenatal care includes counselling and education. This topic provides an overview for the antenatal management of healthy pregnant women with singleton pregnancies.

Routine antenatal care

Overview

OVERVIEW

• At the second visit, a review of laboratory results will promote further discussion of a management plan. • An initial examination will identify women with female genital mutilation (FGM). Because FGM may adversely affect birth outcomes and increase risk for obstetric complications,[10] [11] these patients may have special intrapartum care needs. • If the woman has had a prior caesarean delivery, the risks and benefits of a trial of labour versus repeat caesarean delivery should be reviewed.[2] Candidacy for a trial of labour after caesarean should also be considered. • Antenatal care visits should be scheduled at appropriate intervals to ensure time-sensitive testing and screenings, administration of anti-D immunoglobulin if needed, and monitoring for common complications. • Typical frequency of visits in an uncomplicated pregnancy: ◊ Every 4 weeks for the first 28 weeks ◊ Every 2 to 3 weeks between 28 and 36 weeks ◊ Weekly after 36 weeks. • More frequent visits may occur at the antenatal care provider's discretion or at a patient’s request. Typical visits include evaluation of blood pressure, weight, testing urine for protein levels, and checking the fetal heart rate. • In areas with limited resources, reduced-visit programmes are associated with an increase in perinatal mortality compared with standard practice, although neonatal intensive care admissions may be reduced. Women also prefer the standard visits schedule. While fewer visits may be associated with lower costs, a standard visit schedule should be recommended to all patients.[12] • Screening for depression, which is common during pregnancy and the postnatal period, may be beneficial, particularly in women with a history of major depression. This enables the recognition of patients that may benefit from targeted therapy. Undiagnosed and untreated psychiatric illness is a risk to both the mother and fetus.[13] [14] • Psychosocial screening to ascertain any existing anxiety, depression and other aspects (e.g., evidence of domestic abuse) should be considered. The American Congress of Obstetricians and Gynecologists (ACOG) recommends performing psychosocial screening at least once each trimester to identify issues that may require further evaluation, intervention, or outside referral.[15] • ACOG and the Centers for Disease Control and Prevention (CDC) recommend that all women who will be pregnant through the influenza season (October through May) undergo (inactivated) influenza vaccination. ACOG and the CDC additionally recommend tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccination for pregnant women, ideally between 27 and 36 weeks of gestation.[16] • Appropriate fetal growth can be screened by measuring fundal height (symphysis to uterine fundus) from 20 to 24 weeks' gestation, although most studies suggest that the sensitivity of fundal height as a measurement of growth restiction is <50%. Fundal height in centimetres is approximately equal to the gestation age in weeks. Discrepancies of >3 cm should prompt ultrasound evaluation of amniotic fluid index and fetal growth. The antenatal care provider should keep in mind that fundal height measurements can be influenced by numerous factors, including maternal size, bladder filling, uterine fibroids, multiple gestations, and fetal presentation.[17] [18] • Expectant mothers are questioned regarding pain, fetal movement, contraction frequency, vaginal bleeding, loss of fluid or discharge, other symptoms of preterm labour, and pre-eclampsia symptoms at appropriate gestation intervals, in addition to any other patient-provided complaints or concerns. Nutritional counselling • Nutritional education should focus on a well-balanced, varied, nutritional food plan consistent with the patient's food preferences. Obstetrical care providers should calculate a woman’s BMI at the first antenatal visit. Using BMI as a guideline, appropriate weight gain should be discussed.[19] [Institute of Medicine: weight gain during pregnancy: reexamining the guidelines]

Routine antenatal care

Overview

OVERVIEW

Weight gain during pregnancy Adapted from Institute of Medicine. Weight gain during pregnancy: re-examining the guidelines. 2009

• A nutritional consultation may be offered to obese pregnant women. Obese women should be counselled on healthy eating, and encouraged to participate in physical activity which will support weight management during and after pregnancy.[20] [NICE: weight management before, during and after pregnancy] • Weight gain and caloric intake recommendations are higher for women pregnant with twins or higherorder multiple gestations. The daily recommended caloric intake for women with a normal BMI, who are pregnant with twins, is 40-45 kcal/kg daily.[21] Additional iron, folate, calcium, magnesium, and zinc supplementation may also be required for patients carrying multiple gestations over routine antenatal vitamin intake. • Gestational weight gain greater than or less than Institute of Medicine guidelines appears to be associated with higher risk of some adverse maternal and newborn outcomes.[22] • Diet and physical activity-based interventions in pregnancy are beneficial and can reduce gestational weight gain, as well as the rate of caesarean delivery.[23] • The US Food and Drug Administration has made specific recommendations about fish intake for women of childbearing age. [FDA: eating fish - what pregnant women and parents should know] • Listeriosis is a bacterial illness that can be particularly harmful to pregnant women, possibly resulting in miscarriage or stillbirth. To prevent listeriosis, pregnant women should avoid unpasteurised milk, soft cheeses, raw or undercooked meat, poultry, and shellfish, pâté (any type, including vegetable), and any uncooked or undercooked ready-prepared meals. Additionally, pregnant women can reduce their risk of Salmonella infection by avoiding raw or partially cooked eggs or food that may contain them (e.g., mayonnaise) and raw or partially cooked meat, especially poultry.[2] [7] • Daily antenatal vitamins containing folate (400 micrograms/day) are recommended as tolerated throughout pregnancy, and at least through the first 3 months of pregnancy. Ideally, women should start folate supplementation 12 weeks prior to conception. Selected presentations, such as a prior pregnancy complicated by fetal neural tube defect, require higher-dose folate intake of 4 mg/day. When started preconceptually and continued through pregnancy, folic acid supplementation may reduce the risk of small-for-gestational-age neonates at birth.[24] • While observational data suggest that omega-3 fatty acid docosahexaeonic acid (DHA) supplementation has a beneficial effect on paediatric neurodevelopmental outcomes, randomised controlled trials have yielded conflicting results. At present, there is insufficient evidence to support DHA supplementation to prevent preterm birth.[25] There is also no evidence that such supplementation reduces the risk of pre-eclampsia or gestational diabetes mellitus.[26] • The Royal College of Obstetricians and Gynaecologists (RCOG) recommends supplementation of vitamin D in women at risk of deficiency; however, more research is required to establish appropriate dosing.[27] A more recent National Institute for Health and Care Excellence (NICE) guideline recommends vitamin D supplementation (10 micrograms/day) during pregnancy and while breastfeeding.[7] • Vitamin C and E supplementation during pregnancy does not prevent pre-eclampsia.[28] While it may potentially have some benefit for the prevention of placental abruption and preterm premature rupture This PDF of the BMJ Best Practice topic is based on the web version that was last updated: Feb 07, 2019. BMJ Best Practice topics are regularly updated and the most recent version of the topics can be found on bestpractice.bmj.com . Use of this content is subject to our disclaimer. © BMJ Publishing Group Ltd 2020. All rights reserved.

Routine antenatal care

Overview

OVERVIEW

of membranes (PPROM), vitamin C alone or in combination with other supplements is unproven to reduce the risk of fetal or neonatal death, poor fetal growth, pre-eclampsia, or preterm birth.[29] • Moderate caffeine intake does not appear to have negative effects on pregnancy; however, caffeine intake should be limited to <200 mg daily.[30]

Education

• Education to promote maternal and fetal health and safety is a significant component of antenatal care. Topics that should be discussed at first antenatal visit include promotion of healthy behaviours, dental care, nutrition, wearing a seat belt, continued exercise, avoiding substance and hazardous-chemical exposure, and minimal use of hot tubs or saunas, and potential exposure to domestic violence. Sexual activity may also be discussed. If women use tobacco products, smoking cessation should be encouraged and support provided.[31] [NICE: smoking - stopping in pregnancy and after childbirth] • Alcohol consumption is contraindicated in pregnancy. The UK Department of Health guidelines recommend that for pregnant women and women planning a pregnancy, the safest approach is not to drink alcohol at all, to keep risks to the baby to a minimum.[32] Antenatal drinking poses potentially serious consequences to both mother and fetus. Brief standardised screening questionnaires (Tolerance, Annoyance, Cut down, Eye opener [T-ACE], Alcohol Use Disorders Identification Test [AUDIT-C], Tolerance, Worried, Eye-opener, Amnesia, Cut down [TWEAK]) show promise as screening tools to identify risk drinking in pregnant women, although further investigation is required.[33] • Specific issues to consider:[8] [34] ◊ Breastfeeding: throughout antenatal care, healthcare providers should provide information about the benefits of breastfeeding and breastfeeding support should be provided.[35] ◊ Working: most women with an uncomplicated pregnancy can typically continue working until the onset of labour. However, if women have medical complications or other pregnancy complications, or the occupation involves physical work, prolonged standing, or significant stress, some adjustments may need to be made. ◊ Air travel: women with uncomplicated pregnancies can fly safely until 36 weeks' gestation. Pregnant women who are planning to fly should be informed about the increased risks of venous thromboembolism from the combination of pregnancy and venous stasis, and instructed to take appropriate precautions (support stockings, movement of lower extremities, hydration).[36] [37] ◊ Exercise: women should be encouraged to continue or begin a moderate aerobic exercise programme during pregnancy. [NICE: weight management before, during and after pregnancy] Although the limited available randomised controlled trial data do not clearly support a benefit of exercise during pregnancy for the prevention of glucose intolerance or gestational diabetes mellitus,[38] there may be other physical and psychological benefits derived from aerobic exercise in pregnancy. Structured physical exercise has been demonstrated to significantly reduce the risk of delivering a macrosomic or large-for-gestational-age newborn without influencing the risk of having a small newborn.[39] When not otherwise contraindicated, physical exercise during pregnancy may reduce risk of caesarean delivery.[40] Potential risks from contact sports, high-impact sports, activities with risk of abdominal trauma, and scuba diving should also be discussed. ◊ Childbirth education: attendance in childbirth education classes may be considered. Classes teach expectant mothers about labour and delivery, pain relief options, potential obstetric complications and procedures, normal newborn care, and postnatal adjustment. ◊ Miscellaneous: other educational issues to discuss during the antepartum period include postnatal contraception and circumcision of male infants.

Routine testing All patients should be advised to have a full blood count (FBC), blood type, urinary glucose measurement, urine dipstick and culture, Rhesus and rubella status, with review of last cervical screening. Screening for STIs should be considered (to include syphilis, hepatitis B, HIV infection, gonorrhoea, and chlamydia).[41] All expectant mothers should be offered ultrasound. Other investigations may be performed as indicated.

Routine antenatal care

Overview

OVERVIEW

Recommended routine testing From the collection of Dr L.M. Szymanski and Dr J.L. Bienstock, amended by Dr M.E. D'Alton and Dr R.S. Miller

Routine screening for bacterial vaginosis in asymptomatic women and women not at risk for preterm delivery is not recommended. [Society of Obstetricians and Gynaecologists of Canada: No. 211 - screening and management of bacterial vaginosis in pregnancy]

This PDF of the BMJ Best Practice topic is based on the web version that was last updated: Feb 07, 2019. BMJ Best Practice topics are regularly updated and the most recent version of the topics can be found on bestpractice.bmj.com . Use of this content is subject to our disclaimer. ÂŠ BMJ Publishing Group Ltd 2020. All rights reserved.

Routine antenatal care

Overview

OVERVIEW

Additional tests to consider Some public health departments require additional testing (e.g., more frequent syphilis screening). In addition to routine laboratory tests, several other screening tests should also be considered, many of which are based on racial and ethnic background or family history. STIs • Patients living in areas with high rates of STIs, or those patients with previous antepartum STI, should be considered for repeat STI testing in the third trimester. Vitamin D • Screening for vitamin D deficiency during pregnancy has been advocated by some,[42] particularly for at-risk women, including women with dark skin, those who live in northern latitudes, and women whose clothing leaves little skin exposed. However, it remains controversial because other experts, including the American Congress of Obstetricians and Gynecologists (ACOG), believe existing data are insufficient to offer specific guidelines, especially regarding safety and efficacy of supplementation.[43] However, when deficiency is identified during pregnancy, supplementation with 1000-2000 units/day of vitamin D is considered to be safe.[43] The Institute of Medicine has published a report on the dietary reference intakes for calcium and vitamin D advising an Estimated Average Requirement (EAR) for vitamin D of 400 IU/day (10 micrograms/day) with a Recommended Daily Allowance (RDA) of 600 IU/day (15 micrograms/day) during pregnancy.[44] A 2019 updated NICE guideline recommends vitamin D supplementation (10 micrograms/day) during pregnancy and while breastfeeding.[7] Thyroid function tests • Universal screening for subclinical hypothyroidism is controversial. Although several major societies favour routine screening in women who are pregnant or planning pregnancy,[45] ACOG maintains that data are insufficient to warrant routine screening and continues to recommend testing in symptomatic women and those with a personal history of thyroid disease or other medical conditions associated with thyroid disease.[46] [47] To date, evidence does not support treatment of subclinical hypothyroidism as an intervention to improve pregnancy outcome.[46] [47] [48] Carrier screening Ideally, genetic counselling should be performed before carrier screening.[49] ACOG recommends that all patients who are considering pregnancy or already pregnant are offered screening/tests for:[50] • Cystic fibrosis • Spinal muscular atrophy • FBC and screening for thalassaemias and haemoglobinopathies. Haemoglobin electrophoresis should be performed in addition to a full blood count if haemoglobinopathy is suspected based on African, Mediterranean, Middle Eastern, Southeast Asian, or West Indian ethnicity.[49] Supplemental ethnic-based screening strategies also include:[50] • Tay-Sachs disease (Ashkenazi Jews, French Canadians, Cajuns) • Screening panels that detect mutations associated with disorders that commonly occur in Ashkenazi Jewish populations: Bloom syndrome, Canavan disease, cystic fibrosis, familial dysautonomia, Fanconi anaemia group C, Gaucher disease, glycogen storage disease type 1a, maple syrup urine disease types 1A and 1B, mucolipidosis IV, Niemann-Pick disease type A, and Tay-Sachs disease. Additional testing can be considered depending upon familial history, or on patient and physician preference: • Fragile X syndrome for women with a family history of fragile X-related disorders or intellectual disability suggestive of fragile X syndrome, or women with a personal history of ovarian insufficiency; additional screening may be indicated based on family history or ancestry[50] • Haemochromatosis for people of Celtic ancestry (especially if a positive family history exists)

Routine antenatal care

Overview

• Duchenne's muscular dystrophy.

Ultrasonography First trimester ultrasound screening is optimal for pregnancy dating; however, a complete anatomic evaluation cannot be performed at this time. Advantages of first trimester ultrasonography include its ability to help determine gestational age and evaluate for multiple gestation.[7] If a size-dates discrepancy is present upon initial examination, or if menstrual dates are uncertain, an ultrasound examination is indicated for accurate dating. An ultrasound performed for first-trimester aneuploidy screening will also provide accurate dating information.[52] An ultrasound examination performed between 18 and 22 weeks is optimal for a survey of the fetal anatomy and placental location. It can also confirm pregnancy dating if an earlier ultrasound was not performed. Any pregnancy without ultrasound examination confirming or revising the estimated due date before 22 weeks of gestation is considered suboptimally dated.[53] The sensitivity of ultrasound to detect fetal anomalies ranges from 13% to 82%, depending on the type of anomaly, the level of risk in the population, and the expertise of the operators. Additional ultrasound examinations are not necessary unless maternal or fetal indications are present, although a common practice for incomplete anatomical surveys includes an interval follow-up ultrasound study. Women should be informed of the limitations of routine ultrasound.[8] [52] [54] Ultrasonography in pregnancy is not associated with adverse maternal, perinatal, or childhood outcomes, however, it is recommended that the As Low As Reasonably Achievable (ALARA) principle is followed in order to expose patients to the least amount of ultrasound energy needed to obtain diagnostic information.[55] [56]Long-term follow-up data from a randomised controlled trial found no significant effect of second-trimester ultrasound exposure on overall school performance in teenagers.[57] Obese patients should be informed that their fetus is at increased risk for congenital anomalies, including undiagnosed anomalies.[58] Sonographic fetal anatomical assessment may be better performed at 20 to 22 weeks in obese patients. Routine second trimester ultrasound examination will reveal placental location and relationship to the internal cervical os. Placenta praevia complicates 0.3% to 0.5% of pregnancies. The majority (>80%) of praevia cases diagnosed at 20 weeks resolve by term. Thus, a follow-up ultrasound in the third trimester, usually around 32 weeks, is warranted, as this information may influence delivery planning.[7] [52] [59] [60]

Screening for genetic abnormalities Aneuploidy • Defined as an abnormal number of chromosomes, with 46 chromosomes representing normal in humans. • There may be fewer chromosomes, as in Turner's syndrome (monosomy X), or more chromosomes, as in Down's syndrome (trisomy 21) or other trisomies. • Chromosomal abnormalities occur in 1:160 live births, with trisomy 21 (Down's syndrome), trisomy 18, and trisomy 13 accounting for the majority. Trisomy 18 and trisomy 13 are often incompatible with survival.[61] • Although the frequency of aneuploidies increases with advancing maternal age, they can present at any age (most children with Down's syndrome are actually born to women younger than 35 years of age). The American Congress of Obstetricians and Gynecologists (ACOG) recommends that all women, regardless of age, who present for antenatal care before 20 weeks should be offered aneuploidy screening.[62] Women should be counselled on the age-related risk of fetal aneuploidy, the implications of a diagnosis, and all available screening tests, including their advantages and disadvantages. In addition, all women should have the option of invasive antenatal testing (chorionic villus sampling [CVS] or amniocentesis) for diagnosis of fetal aneuploidy and other genetic anomolies. Screening tests for aneuploidy This PDF of the BMJ Best Practice topic is based on the web version that was last updated: Feb 07, 2019. BMJ Best Practice topics are regularly updated and the most recent version of the topics can be found on bestpractice.bmj.com . Use of this content is subject to our disclaimer. © BMJ Publishing Group Ltd 2020. All rights reserved.

OVERVIEW

Expanded carrier screening represents an alternative approach in which a large number of conditions are screened for simultaneously, and modern products can screen for as many as several hundred conditions. This approach is gaining in popularity due to its efficiency and cost value.[51]

Routine antenatal care

Overview

OVERVIEW

• A variety of screening tests are available, incorporating maternal age, ultrasound, and/or biochemical markers. • First-trimester screening may be performed from 11 to 13 weeks' gestational age and includes ultrasound evaluation for nuchal translucency thickness plus maternal serum screening (pregnancyassociated plasma protein A, human chorionic gonadotrophin). The detection rate for Down's syndrome, at a positive screening rate of 5%, ranges from 82% to 90%.[61] [62] [63] Adding evaluation of the nasal bone, which is absent in 60% to 70% of fetuses with Down's syndrome, can increase the detection rate to 95%. Technical standards and guidelines are available.[64] • Second-trimester screening includes a maternal quadruple marker screening (human chorionic gonadotrophin, alpha-fetoprotein, oestriol, and inhibin), with a detection rate for Down's syndrome of 81%.[61] [62] • Combining screening results from both first- and second-trimester screening tests (i.e., integrated and sequential screening) can improve aneuploidy detection rates.[61] [62] • It is important to be aware that when maternal serum is screened for the usual clinical indications (i.e., aneuploidy and neural tube defect), abnormal analyte results may also identify pregnancies at risk for adverse outcomes, such as pre-eclampsia, and these women should be referred for appropriate follow-up or consultation.[65] • Non-invasive antenatal aneuploidy screening for trisomies 21, 18, and 13 using cell-free fetal DNA is an option that has more recently become available to women with pregnancies at increased risk of aneuploidy.[66] Cell-free fetal DNA screening has high sensitivity and specificity for trisomies 18 and 21, and lower sensitivities for trisomy 13 and sex chromosome abnormalities. Patients should be informed that cell-free fetal DNA is not a substitute for definitive CVS or amniocentesis results, and it is limited in its ability to detect all chromosomal abnormalities and other genetic conditions. • The ACOG currently discourages universal cell-free fetal DNA screening and instead recommends conventional screening among the general low-risk obstetric population.[67] • The ACOG and the Society for Maternal-Fetal Medicine consider appropriate potential candidates for routine cell-free fetal DNA screening to include: maternal age of 35 or older at delivery, fetal ultrasound findings that indicate an increased risk of aneuploidy, history of a previous pregnancy with a trisomy detectable by fetal DNA screening, positive screen results for aneuploidy using another screening modality, and paternal balanced Robertsonian translocation with increased risk for fetal trisomy 13 or 21.[67] [66] [68] • Cell-free fetal DNA may be offered to appropriately counselled patients regardless of risk status.[67] • Importantly, as cell-free fetal DNA testing is a screening study and not a diagnostic test, negative results cannot entirely exclude the possibility for aneuploidy and positive results should be confirmed with invasive genetic testing. • Ultrasound: second-trimester ultrasound can be used to detect fetal anatomical markers associated with aneuploidy that may modify a pregnancy’s risk of carrying an affected fetus. Examples of these sonographic markers include an echogenic intracardiac focus, absent nasal bone, short humerus or femur, and echogenic bowel.[52] [61] [62] • Whichever screening test is used, the patient should be advised that screening provides an individual risk assessment, but it is not diagnostic. Definitive genetic diagnosis requires invasive genetic testing. • Patients who desire definitive genetic information regarding their pregnancies should be counselled to consider invasive genetic testing. If interested, these patients should be referred to genetic counsellors for further discussion. Invasive testing[69] • Invasive testing is necessary to definitively diagnose chromosomal abnormalities. In addition to conventional karyotype determination, comparative genomic hybridisation microarray study is recommended in pregnancies complicated by a fetal anomaly.[70] [71] Among women with structurally normal fetuses undergoing invasive diagnostic testing, either karyotype or chromosomal microarray analysis can be performed, and in many practices both are performed. • All women with a positive screening test, a risk result they are uncomfortable with, or an interest in invasive genetic testing should be offered genetic counselling and diagnostic testing. • Options for invasive genetic testing include CVS (at 10-13 weeks) and diagnostic amniocentesis (at ≥15 weeks). Patient counselling requires a discussion regarding the risks and benefits of each procedure, and a comparison of the relative merits and disadvantages between procedures. • Any discussion of invasive testing options must include disclosure that the procedure may cause obstetrical complications such as pregnancy loss or preterm rupture of membranes.

Routine antenatal care

Overview

Some women may choose to bypass screening and proceed directly to diagnostic testing.[62] The option of invasive genetic testing should be available to all patients regardless of age or prior aneuploidy risk level.

There are 2 approaches for NTD screening: 1. Maternal serum alpha-fetoprotein (MS-AFP) in the second trimester (15 to 22 weeks' gestation, optimal at 16 to 18 weeks) 2. Ultrasound. MS-AFP has historically been used as a screening test: the standard screening cut-off, of 2.5 multiples of the median, detects about 80% of cases of open spina bifida and 90% of cases of anencephaly. If women screen positive, a detailed ultrasound is performed: • To ensure that the pregnancy is viable and accurately dated • To evaluate for the presence of multiple gestations • To assess fetal anatomy for NTDs and other defects associated with an elevated MS-AFP (omphalocoele, gastroschisis, cystic hygroma).[2] Amniocentesis can be performed to determine if amniotic fluid AFP is elevated and acetylcholinesterase is present, which are considered diagnostic of a NTD.[2] [72] [73] At present ultrasound is favoured over MS-AFP as a screening tool although these 2 screening modalities are not mutually exclusive. With experienced sonographers, the detection rate of NTDs approaches 95% to 100%.[72] [73]

Screening for gestational diabetes mellitus The National Institute for Health and Care Excellence (NICE) recommends risk assessment for gestational diabetes mellitus likelihood using risk factors in a healthy population.[74] The following risk factors are recommended: • • • • •

BMI (kg/m²) >30 Previous macrosomic baby weighing ≥4.5 kg Previous pregnancy involving gestational diabetes Family history of diabetes in a first-degree relative Minority ethnic family origin with high diabetes prevalence.

NICE recommends that all women with at least one risk factor be tested for gestational diabetes using a 2hour, 75 g oral glucose tolerance test (OGTT).[74] Women with gestational diabetes in a prior pregnancy should be considered for early OGTT in the first or second trimester, or alternatively they may perform early self-monitoring of blood glucose. If this early screening is normal, further OGTT screening between 24 and 28 weeks is recommended among women with personal gestational diabetes history. For women with all other risk factors, a single OGTT at 24 to 28 weeks is recommended. Additionally, glycosuria of 2+ any time in pregnancy or 1+ on two or more visits should prompt further testing to exclude gestational diabetes. The US Preventive Services Task Force (USPSTF) recommends screening for gestational diabetes mellitus in asymptomatic pregnant women after 24 weeks of gestation by using either a two-step approach (i.e., 50 g oral glucose challenge test [GCT] followed by a 100 g glucose tolerance test in those who screen as GCT positive) or by using a one-step approach (i.e., a 75 g glucose challenge).[75] While the USPSTF concludes there are insufficient data to support routine screening prior to 24 weeks, screening may be considered among women who are considered to be high risk for gestational diabetes. The American Congress of Obstetricians and Gynecologists (ACOG) supports universal screening of all pregnant women by medical history, clinical risk factors, or laboratory screening test, with screening usually performed at 24 to 28 weeks.[76] Among women considered to be at high risk for diabetes, early screening may be performed. If normal, repeat screening is recommended at 24 to 28 weeks. Two-step laboratory screening is supported by the ACOG. The ACOG does not recommend a one-step OGTT due to concern This PDF of the BMJ Best Practice topic is based on the web version that was last updated: Feb 07, 2019. BMJ Best Practice topics are regularly updated and the most recent version of the topics can be found on bestpractice.bmj.com . Use of this content is subject to our disclaimer. © BMJ Publishing Group Ltd 2020. All rights reserved.

OVERVIEW

Screening for neural tube defects (NTDs)

Routine antenatal care

Overview

OVERVIEW

that this practice would increase the incidence of a diagnosis of gestational diabetes and resultant healthcare costs without evidence to support an improvement in maternal or newborn outcomes.

Screening for group B Streptococcus (GBS) In the UK screening for GBS, colonisation is not performed routinely. Elsewhere, screening may be offered. For example, in the US, all pregnant women are offered screening for vaginal-rectal GBS colonisation at 35 to 37 weeks' gestation.[77] Intravenous antibiotics should be given to all pregnant women identified as GBS carriers at the time of labour or rupture of membranes. Colonisation during a previous pregnancy is not an indication for intrapartum prophylaxis in a subsequent pregnancy. Women with GBS isolated from the urine in any concentration during pregnancy or who have a previous infant with GBS infection should also receive intrapartum prophylaxis.[77] For patients presenting with unknown GBS colonisation status, anticipated premature delivery <37 weeks, rupture of membranes 18 hours or longer prior to delivery, and maternal temperature of 38.0°C (100.4°F) or greater without evidence of chorioamnionitis are considered reasons to initiate intrapartum prophylaxis.

Rho D immune globulin administration Rhesus (Rh)-negative women should receive Rho D immune globulin if they have any of the following:[2] • • • • •

An ectopic pregnancy Miscarriage or termination of pregnancy Any invasive procedures (amniocentesis, chorionic villus sampling) Possibility of fetal-maternal haemorrhage (abdominal trauma, placental abruption) If they deliver a neonate who is Rh-positive.

Rh-negative women should be given Rho D immune globulin at 28 weeks' gestation. The patient may decline administration if paternity is certain, and the father of the pregnancy is known to be Rh-negative.[2] [7] [78]

Diagnosis and treatment of anaemia in pregnancy Anaemia in pregnancy has been defined as haemoglobin (Hb) levels <110 g/L (<11 g/dL) and haematocrit (Hct) levels <33% in the first and third trimester, and Hb levels <105 g/L (<10.5 g/dL) and Hct levels <32% in the second trimester.[79] Anaemia in pregnancy can be diluational (physiological), due to iron, folate or other vitamin deficiency, a result of thalassemias, or result from other causes. Obstetrical care providers should consider a work-up for causes of anaemia in pregnancy. In the UK, routine iron supplementation is not recommended.[80] In the US, the CDC recommends daily elemental iron supplementation for prophylaxis or treatment of iron-deficiency anaemia. Absorption of iron can be facilitated with vitamin C.[81] [82] [83]

Management of post-term pregnancy Post-term pregnancy is defined by the World Health Organization as a gestation that has extended to or beyond 42 weeks. Perinatal mortality at >42 weeks' gestation is twice that at term. Although differences exist between published practice guidelines, women may be offered induction of labour by 41 weeks' gestation (late-term gestation) to avoid risks of post-term pregnancy.[84] [NICE: inducing labour] If pregnancy continues beyond 41 weeks, fetal testing should be initiated, although the optimal type or frequency of testing is not known.[84] [85]

Obesity Obese women should also be informed that they are at risk for pregnancy complications including gestational hypertension, gestational diabetes mellitus, cardiac disease, pulmonary disease, obstructive sleep apnoea, and caesarean delivery.[58] Regular aerobic exercise during pregnancy may reduce some of these risks. While evidence indicates that monitored physical activity appears to limit gestational weight gain among

Routine antenatal care

Overview

overweight or obese pregnant women, effects on maternal and neonatal health are unproven.[86] Antenatal dietary modifications in obese pregnant women can reduce maternal weight gain during pregnancy without adversely influencing neonatal birth weight.[87]

Obesity further appears to be associated with an increased risk of selected fetal malformations and stillbirth, as well as a more limited ability to sonographically detect anomalies during the antenatal period.[88]

Guidelines In the UK, the National Institute for Health and Care Excellence (NICE) has produced the following guidelines and guidance: • • • •

Antenatal care for uncomplicated pregnancies[7] Diabetes in pregnancy: management from preconception to the postnatal period[74] Antenatal and postnatal mental health: clinical management and service guidance[89] Routine antenatal anti-D prophylaxis for women who are rhesus D negative.[78]

Guidelines are also available from a number of professional societies on screening for chromosomal abnormalities and neural tube defects: • Royal College of Obstetrics and Gynaecologists (UK). Amniocentesis and chorionic villus sampling[90] • Society of Obstetricians and Gynaecologists of Canada and Canadian College of Medical Geneticists. Prenatal screening for foetal aneuploidy in singleton pregnancies[91] • Society of Obstetricians and Gynaecologists of Canada. Evaluation of prenatally diagnosed structural congenital anomalies[92] • Society of Obstetricians and Gynaecologists of Canada Genetics Committee. Obstetrical complications associated with abnormal maternal serum markers analytes.[65] Specific guidelines include: • Royal College of Obstetrics and Gynaecologists (UK). Reducing the risk of thrombosis and embolism during pregnancy and the puerperium[36] • Royal College of Obstetrics and Gynaecologists (UK). Air travel and pregnancy[37] • Society of Obstetricians and Gynaecologists of Canada. Immunization in pregnancy[93] • Society of Obstetricians and Gynaecologists of Canada. Pre-conception folic acid and multivitamin supplementation for the primary and secondary prevention of neural tube defects and other folic acidsensitive congenital anomalies[94] • Royal College of Obstetrics and Gynaecologists (UK). Female genital mutilation and its management.[11]

OVERVIEW

Obese patients may also be at increased risk for venous thromboembolism, particularly if other risk factors are present. Thromboprophylaxis should be considered on an individual basis based upon a patient’s risk profile. Antenatal consultation with an anaesthetist should be considered for patients with Class III obesity (BMI 40 or above), to discuss interventions (such as an early epidural) that may limit intrapartum risk.

Routine antenatal care

Online resources

Online resources US Department of Health and Human Services: prenatal care fact sheet (external link)

International Diabetes Federation: global guideline on pregnancy and diabetes (external link)

CDC: guidelines for vaccinating pregnant women (external link)

Institute of Medicine: weight gain during pregnancy: reexamining the guidelines (external link)

NICE: weight management before, during and after pregnancy (external link)

FDA: eating fish - what pregnant women and parents should know (external link)

NICE: smoking - stopping in pregnancy and after childbirth (external link)

Society of Obstetricians and Gynaecologists of Canada: No. 211 - screening and management of bacterial vaginosis in pregnancy (external link)

NICE: inducing labour (external link)

ONLINE RESOURCES

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Routine antenatal care

References

Key articles American Academy of Pediatrics; American College of Obstetricians and Gynecologists. Guidelines for perinatal care. 8th ed. American Academy of Pediatrics and American College of Obstetricians and Gynecologists; 2017.

•

National Institute for Health and Care Excellence. Antenatal care for uncomplicated pregnancies. Feb 2019 [internet publication]. Full text

•

Driscoll DA, Gross S. Clinical practice: prenatal screening for aneuploidy. N Engl J Med. 2009 Jun 11;360(24):2556-62. Abstract

•

American Congress of Obstetricians and Gynecologists. Committee opinion no. 640: Cell-free DNA screening for fetal aneuploidy. Obstet Gynecol. 2015 Sep;126(3):e31-7. Abstract

•

National Institute for Health and Care Excellence. Diabetes in pregnancy: management from preconception to the postnatal period. August 2015 [internet publication]. Full text

•

National Institute for Health and Care Excellence. Antenatal and postnatal mental health: clinical management and service guidance. February 2020 [internet publication]. Full text

References 1.

Posner SF, Johnson K, Parker C, et al. The national summit on preconception care: a summary of concepts and recommendations. Matern Child Health J. 2006 Sep;10(5 Suppl):S197-205. Full text Abstract

American Academy of Pediatrics; American College of Obstetricians and Gynecologists. Guidelines for perinatal care. 8th ed. American Academy of Pediatrics and American College of Obstetricians and Gynecologists; 2017.

Korenbrot CC, Steinberg A, Bender C, et al. Preconception care: a systematic review. Matern Child Health J. 2002 Jun;6(2):75-88. Abstract

Johnson K, Posner SF, Biermann J, et al. Recommendations to improve preconception health and health care - United States. MMWR Recomm Rep. 2006 Apr 21;55(RR-6):1-23. Full text Abstract

Kirkham C, Harris S, Grzybowski S. Evidence-based prenatal care - part II: third-trimester care and prevention of infectious diseases. Am Fam Physician. 2005 Apr 15;71(8):1555-60. Full text Abstract

Gruslin A, Steben M, Halperin S, et al. Immunization in pregnancy. [Erratum in J Obstet Gynaecol Can. 2009;31:209]. J Obstet Gynaecol Can. 2008 Dec;30(12):1149-54. Abstract

National Institute for Health and Care Excellence. Antenatal care for uncomplicated pregnancies. Feb 2019 [internet publication]. Full text

Phelan ST. Components and timing of prenatal care. Obstet Gynecol Clin North Am. 2008 Sep;35(3):339-53. Abstract

Lilford RJ, Kelly M, Baines A, et al. Effect of using protocols on medical care: randomised trial of three methods of taking an antenatal history. BMJ. 1992 Nov 14;305(6863):1181-4. Full text Abstract

REFERENCES

•

REFERENCES

Routine antenatal care

References

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Banks E, Meirik O, Farley T, et al. WHO study group on female genital mutilation and obstetric outcome. Female genital mutilation and obstetric outcome: WHO collaborative prospective study in six African countries. Lancet. 2006 Jun 3;367(9525):1835-41. Abstract

11.

Royal College of Obstetrics and Gynaecologists. Female genital mutilation and its management. Green-top guideline no. 53. July 2015 [internet publication]. Full text

12.

Dowswell T, Carroli G, Duley L, et al. Alternative versus standard packages of antenatal care for lowrisk pregnancy. Cochrane Database Syst Rev. 2015 Jul 16;(7):CD000934 Full text Abstract

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American College of Obstetricians and Gynecologists, Committee on Obstetric Practice. Committee opinion no. 453: screening for depression during and after pregnancy. Obstet Gynecol. 2010 Feb;115(2 Pt 1):394-5. Abstract

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Yonkers KA, Wisner KL, Stewart DE, et al. The management of depression during pregnancy: a report from the American Psychiatric Association and the American College of Obstetricians and Gynecologists. Gen Hosp Psychiatry. 2009 Sep-Oct;31(5):403-13. Abstract

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American College of Obstetricians and Gynecologists Committee on Health Care for Underserved Women. ACOG committee opinion no. 343: psychosocial risk factors: perinatal screening and intervention. Obstet Gynecol. 2006 Aug;108(2):469-77. Abstract

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American College of Obstetricians and Gynecologists Committee on Obstetric Practice. ACOG committee opinion no. 566: update on immunization and pregnancy: tetanus, diphtheria, and pertussis vaccination. Obstet Gynecol. 2013 Jun;121(6):1411-4. Abstract

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American College of Obstetricians and Gynecologists. Risk factors for intrauterine growth restriction. Practice bulletin no. 12. Washington, DC: ACOG; 2000.

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Kirkham C, Harris S, Grzybowski S. Evidence-based prenatal care - part I: general prenatal care and counseling issues. Am Fam Physician. 2005 Apr 1;71(7):1307-16. Full text Abstract

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Kaiser L, Allen LH; American Dietetic Association. Position of the American Dietetic Association: nutrition and lifestyle for a healthy pregnancy outcome. J Am Diet Assoc. 2008 Mar;108(3):553-61. Abstract

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Fitzsimons KJ, Modder J; Centre for Maternal and Child Enquires. Setting maternity care standards for women with obesity in pregnancy. Semin Fetal Neonatal Med. 2010 Apr;15(2):100-7. Abstract

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Goldstein RF, Abell SK, Ranasinha S, et al. Association of Gestational Weight Gain With Maternal and Infant Outcomes: A Systematic Review and Meta-analysis. JAMA. 2017 Jun 6;317(21):2207-25. Full text Abstract

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International Weight Management in Pregnancy (i-WIP) Collaborative Group. Effect of diet and physical activity based interventions in pregnancy on gestational weight gain and pregnancy outcomes: meta-analysis of individual participant data from randomised trials. BMJ. 2017 Jul 19;358:j3119. Full text Abstract

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This PDF of the BMJ Best Practice topic is based on the web version that was last updated: Feb 07, 2019. BMJ Best Practice topics are regularly updated and the most recent version of the topics can be found on bestpractice.bmj.com . Use of this content is subject to our disclaimer. ÂŠ BMJ Publishing Group Ltd 2020. All rights reserved.

Routine antenatal care

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Coletta JM, Bell SJ, Roman AS. Omega-3 fatty acids and pregnancy. Rev Obstet Gynecol. 2010 Fall;3(4):163-71. Full text Abstract

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Zhou SJ, Yelland L, McPhee AJ, et al. Fish-oil supplementation in pregnancy does not reduce the risk of gestational diabetes or preeclampsia. Am J Clin Nutr. 2012 Jun;95(6):1378-84. Abstract

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Royal College of Obstetricians and Gynaecologists. Vitamin D in pregnancy. Scientific impact paper no. 43. June 2014 [internet publication]. Full text

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Conde-Agudelo A, Romero R, Kusanovic JP, et al. Supplementation with vitamins C and E during pregnancy for the prevention of preeclampsia and other adverse maternal and perinatal outcomes: a systematic review and metaanalysis. Am J Obstet Gynecol. 2011 Jun;204(6):503.e1-12. Full text Abstract

29.

Rumbold A, Ota E, Nagata C, et al. Vitamin C supplementation in pregnancy. Cochrane Database Syst Rev. 2015 Sep 29;(9):CD004072. Full text Abstract

30.

American College of Obstetricians and Gynecologists. ACOG committee opinion no. 462: moderate caffeine consumption during pregnancy. Obstet Gynecol. 2010 Aug;116(2 Pt 1):467-8. Abstract

31.

American College of Obstetricians and Gynecologists (ACOG). Committee opinion no. 471: smoking cessation during pregnancy. Obstet Gynecol. 2010 Nov;116(5):1241-4. Abstract

32.

Department of Health. UK Chief Medical Officers’ low risk drinking guidelines. August 2016 [internet publication]. Full text

33.

Burns E, Gray R, Smith LA, et al. Brief screening questionnaires to identify problem drinking during pregnancy: a systematic review. Addiction. 2010 Apr;105(4):601-14. Abstract

34.

Berghella V, Buchanan E, Pereira L, et al. Preconception care. Obstet Gynecol Surv. 2010 Feb;65(2):119-31. Abstract

35.

Academy of Breastfeeding Medicine Protocol Committee. Clinical protocol number #19: breastfeeding promotion in the prenatal setting. Breastfeed Med. 2009 Mar;4(1):43-5. Abstract

36.

Royal College of Obstetrics and Gynaecologists. Reducing the risk of thrombosis and embolism during pregnancy and the puerperium. Green-top guideline no. 37a. April 2015 [internet publication]. Full text

37.

Royal College of Obstetrics and Gynaecologists. Air travel and pregnancy. Scientific impact paper 1. May 2013. http://www.rcog.org.uk Full text

38.

Han S, Middleton P, Crowther CA. Exercise for pregnant women for preventing gestational diabetes mellitus. Cochrane Database Syst Rev. 2012 Jul 11;(7):CD009021. Full text Abstract

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Wiebe HW, Boulé NG, Chari R, et al. The effect of supervised prenatal exercise on fetal growth: a meta-analysis. Obstet Gynecol. 2015 May;125(5):1185-94. Abstract

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Domenjoz I, Kayser B, Boulvain M. Effect of physical activity during pregnancy on mode of delivery. Am J Obstet Gynecol. 2014 Oct;211(4):401.e1-11. Abstract

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U.S. Preventive Services Task Force. Screening for hepatitis B virus infection in pregnancy: reaffirmation recommendation statement. Am Fam Physician. 2010 Feb 15;81(4):502. Abstract

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Wagner CL, Greer FR; American Academy of Pediatrics Section on Breastfeeding. Prevention of rickets and vitamin D deficiency in infants, children, and adolescents. Pediatrics. 2008 Nov;122(5):1142-52. Full text Abstract

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ACOG Committee on Obstetric Practice. ACOG committee opinion no. 495: vitamin D: screening and supplementation during pregnancy. Obstet Gynecol. 2011 Jul;118(1):197-8. Abstract

44.

Ross AC, Taylor CL, Yaktine AL, et al. Dietary reference intakes for calcium and vitamin D. 1st ed. Washington, DC; 2011. Full text Abstract

45.

Gharib H, Tuttle RM, Baskin HJ, et al. Subclinical thyroid dysfunction. J Clin Endocrinol Metab. 2005 Jan;90(1):581-5. Full text Abstract

46.

Committee on Patient Safety and Quality Improvement, Committee on Professional Liability. ACOG committee opinion no. 381: subclinical hypothyroidism in pregnancy. Obstet Gynecol. 2007 Oct;110(4):959-60. Abstract

47.

Surks MI, Ortiz E, Daniels GH, et al. Subclinical thyroid disease: scientific review and guidelines for diagnosis and management. JAMA. 2004 Jan 14;291(2):228-38. Full text Abstract

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Spong CY. Subclinical hypothyroidism: should all pregnant women be screened? Obstet Gynecol. 2005 Feb;105(2):235-6. Abstract

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Committee on Genetics. Committee Opinion No. 691: carrier screening for genetic conditions. Obstet Gynecol. 2017 Mar;129(3):e41-55. Abstract

50.

American College of Obstetricians and Gynecologists. Committee opinion no. 690: carrier screening in the age of genomic medicine. Obstet Gynecol. 2017 Mar;129(3):e35-40. Abstract

51.

Committee on Genetics. Committee Opinion No. 690: Carrier Screening in the Age of Genomic Medicine. Obstet Gynecol. 2017 Mar;129(3):e35-e40. Full text Abstract

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American College of Obstetricians and Gynecologists. ACOG practice bulletin no. 101: ultrasonography in pregnancy. Obstet Gynecol. 2009 Feb;113(2 Pt 1):451-61. Abstract

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Committee on Obstetric Practice. Committee Opinion No. 688: Management of Suboptimally Dated Pregnancies. Obstet Gynecol. 2017 Mar;129(3):e29-e32. Full text Abstract

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Cargill Y, Morin L, Bly S, et al. Content of a complete routine second trimester obstetrical ultrasound examination and report. J Obstet Gynaecol Can. 2009 Mar;31(3):272-5. Abstract

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Torloni MR, Vedmedovska N, Merialdi M, et al; ISUOG-WHO Fetal Growth Study Group. Safety of ultrasonography in pregnancy: WHO systematic review of the literature and meta-analysis. Ultrasound Obstet Gynecol. 2009 May;33(5):599-608. Full text Abstract

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International Society of Ultrasound in Obstetrics and Gynecology. Performance of first-trimester fetal ultrasound scan. January 2013 [internet publication]. Full text

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Stalberg K, Axelsson O, Haglund B, et al. Prenatal ultrasound exposure and children's school performance at age 15-16: follow-up of a randomized controlled trial. Ultrasound Obstetr Gynecol. 2009 Sep;34(3):297-303. Full text Abstract

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Davies GA, Maxwell C, McLeod L, et al. SOGC clinical practice guidelines: obesity in pregnancy. No. 239, February 2010. Int J Gynaecol Obstet. 2010 Aug;110(2):167-73. Abstract

This PDF of the BMJ Best Practice topic is based on the web version that was last updated: Feb 07, 2019. BMJ Best Practice topics are regularly updated and the most recent version of the topics can be found on bestpractice.bmj.com . Use of this content is subject to our disclaimer. ÂŠ BMJ Publishing Group Ltd 2020. All rights reserved.

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Driscoll DA, Gross S. Clinical practice: prenatal screening for aneuploidy. N Engl J Med. 2009 Jun 11;360(24):2556-62. Abstract

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ACOG Committee on Practice Bulletins. ACOG practice bulletin no. 77: screening for fetal chromosomal abnormalities. Obstet Gynecol. 2007 Jan;109(1):217-27. Abstract

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Driscoll DA, Gross SJ; Professional Practice and Guidelines Committee. First trimester diagnosis and screening for fetal aneuploidy. Genet Med. 2008 Jan;10(1):73-5. Abstract

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Palomaki GE, Lee JE, Canick JA, et al; ACMG Laboratory Quality Assurance Committee. Technical standards and guidelines: prenatal screening for Down syndrome that includes first-trimester biochemistry and/or ultrasound measurements. Genet Med. 2009 Sep;11(9):669-81. Abstract

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Gagnon A, Wilson RD, Audibert F, et al; Society of Obstetricians and Gynaecologists of Canada Genetics Committee. Obstetrical complications associated with abnormal maternal serum markers analytes. J Obstet Gynaecol Can. 2008 Oct;30(10):918-32. Full text Abstract

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American Congress of Obstetricians and Gynecologists. Committee opinion no. 640: Cell-free DNA screening for fetal aneuploidy. Obstet Gynecol. 2015 Sep;126(3):e31-7. Abstract

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Committee on Practice Bulletinsâ&#x20AC;&#x201D;Obstetrics, Committee on Genetics, and the Society for MaternalFetal Medicine. Practice Bulletin No. 163: Screening for Fetal Aneuploidy. Obstet Gynecol. 2016 May;127(5):e123-37. Full text Abstract

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American College of Obstetricians and Gynecologists Committee on Genetics. Committee Opinion No. 545: Noninvasive prenatal testing for fetal aneuploidy. Obstet Gynecol. 2012 Dec;120(6):1532-4. Full text Abstract

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American College of Obstetricians and Gynecologists. ACOG practice bulletin no. 88, December 2007. Invasive prenatal testing for aneuploidy. Obstet Gynecol. 2007 Dec;110(6):1459-67. Abstract

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Wapner RJ, Martin CL, Levy B, et al. Chromosomal microarray versus karyotyping for prenatal diagnosis. N Engl J Med. 2012 Dec 6;367(23):2175-84. Full text Abstract

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Cheschier N; ACOG Committee on Practice Bulletins-Obstetrics. ACOG practice bulletin: neural tube defects. Number 44, July 2003. (Replaces committee opinion number 252, March 2001). Int J Gynaecol Obstet. 2003 Oct;83(1):123-33. Abstract

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Cameron M, Moran P. Prenatal screening and diagnosis of neural tube defects. Prenat Diagn. 2009 Apr;29(4):402-11. Abstract

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This PDF of the BMJ Best Practice topic is based on the web version that was last updated: Feb 07, 2019. BMJ Best Practice topics are regularly updated and the most recent version of the topics can be found on bestpractice.bmj.com . Use of this content is subject to our disclaimer. ÂŠ BMJ Publishing Group Ltd 2020. All rights reserved.

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Verani JR, McGee L, Schrag SJ, et al. Prevention of perinatal group B streptococcal disease--revised guidelines from CDC, 2010. MMWR Recomm Rep. 2010 Nov 19;59(rr-10):1-36. Abstract

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89.

National Institute for Health and Care Excellence. Antenatal and postnatal mental health: clinical management and service guidance. February 2020 [internet publication]. Full text

90.

Royal College of Obstetrics and Gynaecologists. Amniocentesis and chorionic villus sampling. Greentop guideline no. 8. June 2010 [internet publication]. Full text

91.

Chitayat D, Langlois S, Wilson RD; Genetics Committee of the Society of Obstetricians and Gynaecologists of Canada; Prenatal Diagnosis Committee of the Canadian College of Medical Geneticists. Prenatal screening for fetal aneuploidy in singleton pregnancies. J Obstet Gynaecol Can. 2011 Jul;33(7):736-50. Full text Abstract

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Gagnon A, Wilson RD, Allen VM,et al; Society of Obstetricians and Gynaecologists of Canada. Evaluation of prenatally diagnosed structural congenital anomalies. J Obstet Gynaecol Can. 2009 Sep;31(9):875-81. Full text Abstract

93.

Gruslin A, Steben M, Halperin S, et al; Infectious Diseases Committee of the Society of Obstetricians and Gynaecologists of Canada. Immunization in pregnancy. J Obstet Gynaecol Can. 2009 Nov;31(11):1085-101. Full text Abstract

94.

Wilson RD, Audibert F, Brock JA, et al; Genetics Committee of the Society of Obstetricians and Gynaecologists of Canada. Pre-conception folic acid and multivitamin supplementation for the primary and secondary prevention of neural tube defects and other folic acid-sensitive congenital anomalies. J Obstet Gynaecol Can. 2015 Jun;37(6):534-52. Full text Abstract

This PDF of the BMJ Best Practice topic is based on the web version that was last updated: Feb 07, 2019. BMJ Best Practice topics are regularly updated and the most recent version of the topics can be found on bestpractice.bmj.com . Use of this content is subject to our disclaimer. ÂŠ BMJ Publishing Group Ltd 2020. All rights reserved.

REFERENCES

92.

Routine antenatal care

Images

IMAGES

Images

Figure 1: Weight gain during pregnancy Adapted from Institute of Medicine. Weight gain during pregnancy: re-examining the guidelines. 2009

This PDF of the BMJ Best Practice topic is based on the web version that was last updated: Feb 07, 2019. BMJ Best Practice topics are regularly updated and the most recent version of the topics can be found on bestpractice.bmj.com . Use of this content is subject to our disclaimer. ÂŠ BMJ Publishing Group Ltd 2020. All rights reserved.

Routine antenatal care

Images

IMAGES

Figure 2: Recommended routine testing From the collection of Dr L.M. Szymanski and Dr J.L. Bienstock, amended by Dr M.E. D'Alton and Dr R.S. Miller

This PDF of the BMJ Best Practice topic is based on the web version that was last updated: Feb 07, 2019. BMJ Best Practice topics are regularly updated and the most recent version of the topics can be found on bestpractice.bmj.com . Use of this content is subject to our disclaimer. ÂŠ BMJ Publishing Group Ltd 2020. All rights reserved.

Routine antenatal care

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This PDF of the BMJ Best Practice topic is based on the web version that was last updated: Feb 07, 2019. BMJ Best Practice topics are regularly updated and the most recent version of the topics can be found on bestpractice.bmj.com . Use of this content is subject to our disclaimer. ÂŠ BMJ Publishing Group Ltd 2020. All rights reserved.

Contributors: // Authors: Mary E. D'Alton, MD Chair Department of Obstetrics and Gynecology, Columbia University Medical Center, New York, NY DISCLOSURES: MED declares that she is a member of the advisory board for Merck for Mothers. Russell S. Miller, MD Associate Professor of Obstetrics and Gynecology Department of Obstetrics and Gynecology, Columbia University Medical Center, New York, NY DISCLOSURES: RSM declares that he has no competing interests.

// Acknowledgements: Dr Mary E. D'Alton and Dr Russell S. Miller would like to gratefully acknowledge Dr Linda M. Szymanski and Dr Jessica L. Bienstock, the previous contributors to this topic. LMS and JLB declare that they have no competing interests.

// Peer Reviewers: Chris Chisholm, MD Associate Professor Residency Program Director, Department of Obstetrics and Gynecology, University of Virginia Health System, Charlottesville, VA DISCLOSURES: CC declares that he has no competing interests. Eva Pressman, MD Director of Maternal Fetal Medicine University of Rochester, School of Medicine and Dentistry, Rochester, NY DISCLOSURES: EP declares that she has no competing interests. Jan Dickinson, MBBS(WA), MD, FRANZCOG, DDU, CMFM Professor Maternal Fetal Medicine School of Women's and Infants' Health, The University of Western Australia, Perth, Western Australia, Australia DISCLOSURES: JD declares that she has no competing interests. Greg Ofili, FRCOG Consultant Obstetrician and Gynaecologist Wishaw General Hospital, Netherton Wishaw, UK DISCLOSURES: GO declares that he has no competing interests.