Week 14 Discussion ~ Maternal-Child Nursing Discuss the phases of the menstrual cycle. Ovarian Cycle In response to GnRH from the Woman’s hypothalamus, the anterior pituitary secretes FSH and LH. The FSH and LH stimulate the ovaries to mature an ovum, release it, and secrete other hormones that will prepare the endometrium for implantation of a fertilized ovum. The ovarian cycle consists of three phases: the follicular phase, the ovulatory phase, and the luteal phase.
Follicular Phase – The follicular phase is the period during which an ovum matures. It begins with the 1st day of menstruation and ends about 14 days later in a 28-day cycle. The length of this phase varies more among different women than do the lengths of the other two phases. The decrease in estrogen and progesterone secretion by the ovary just before menstruation stimulates secretion of FSH and LH by the anterior pituitary. As FSH and LH levels rise, 6 to 12 graafian follicles, each containing an oocyte (immature ovum), start growing faster. Each follicle secretes fluid containing high levels of estrogen, which accelerates maturation by making the follicle more sensitive to the effects of FSH. Eventually one follicle matures before the others. The mature follicle secretes large amounts of estrogen, which depresses FSH secretion. The brief dip in FSH secretion just before ovulation blocks further maturation of the less-developed follicles. Occasionally more than one follicle matures and releases its ovum; this condition can lead to a multifetal pregnancy. Ovulatory Phase – Neat the middle of a 28-day reproductive cycle, about 2 days before ovulation, LH secretion rises markedly. Secretion of FSH also rises, but less than LH does. These surges in LH and FSH cause a slight fall in follicular estrogen production and a rise in progesterone secretion, stimulating final maturation of a single follicle and release of its mature ovum. Ovulation marks the beginning of the luteal phase of the female reproductive cycle and occurs about 14 days before the next menstrual period. The mature follicle is a mass of cells with a fluid-filled chamber. A smaller mass of cells houses the ovum within this chamber. At ovulation, a blister like projection, called a stigma, forms on the wall of the follicle, the follicle ruptures, and the ovum with its surrounding cells is released from the surface of the ovary. It is picked up by the fimbriated end of the fallopian tube for transport to the uterus. Luteal Phase – After ovulation and under the influence of LH, the remaining cells of the old follicle persist for about 12 days as a corpus luteum. The corpus luteum secretes
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Week 14 Discussion ~ Maternal-Child Nursing estrogen and large amounts of progesterone to prepare the endometrium for a fertilized ovum. Levels of FSH and LH decrease during this phase in response to higher levels of estrogen and progesterone. If the ovum is fertilized, it secretes human chorionic gonadotropin (hCG) that causes the corpus luteum to persist to maintain an early pregnancy. If the ovum is not fertilized, FSH and LH fall to low levels, and corpus luteum regresses. Decline of estrogen and progesterone with the regression of the corpus luteum results in menstruation as the uterine lining breaks down. The loss of estrogen and progesterone from the corpus luteum at the end of one cycle stimulates the anterior pituitary to increase secretion of FSH and LH, initiating a new cycle. The old corpus luteum is replaced by fibrous issue called the corpus albicans. Endometrial Cycle The uterine endometrium responds to ovarian hormone stimulation with cyclic changes. Three phases mark the changes in the endometrium: the proliferative phase, the secretory phase, and the menstrual phase.
Proliferative Phase – This phase takes place as the ovum matures and is released during the 1st half of the ovarian cycle. After completion of a menstrual period, the endometrium is very thin, with only the basal layer of cells remaining. These cells multiply to form new endometrial epithelium and endometrial glands under the stimulation of estrogen secreted by the maturing ovarian follicles. Endometrial spiral arteries and endometrial veins elongate to accompany thickening of the functional endometrial later and to nourish the proliferating cells. As ovulation approaches, the endometrial glands secrete a thin, stringy mucus that aids entry of sperm into the uterus. Secretory Phase – The secretory phase occurs during the second half of the ovarian cycle as the uterus is prepared to receive a fertilized ovum. The endometrium continues to thicken under influence of estrogen and progesterone from the corpus luteum, reaching its maximum thickness of 5 to 6 mm. The blood vessels and endometrial glands become twisted and dilated. Progesterone from the corpus luteum causes the thick endometrium to secrete substances that nourish a fertilized ovum. Large quantities of glycogen, proteins, lipids, and minerals are stored within the endometrium, awaiting arrival of the ovum. Menstrual Phase – If fertilization does not occur, the corpus luteum regresses, and its production of estrogen and progesterone falls. Approximately 2 days before the onset of the menses, vasospasm of the endometrial blood vessels causes the endometrium to become ischemic and necrotic. The necrotic areas of endometrium separate from the basal layers, resulting in menstrual flow. The duration of the menstrual phase is about 5 days. During a menstrual period, women lose about 40 mL of blood. Because of the
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Week 14 Discussion ~ Maternal-Child Nursing recurrent loss of blood, many women are mildly anemic during their reproductive years, especially if their diets are low in iron. What are the different types of pelvis?
Upper (False) Pelvis – provides support for the internal organs and the upper part of the body. Lower (True) Pelvis – Is the most important during childbirth.
What are the functions of amniotic fluid? Protects the growing fetus by:
o Cushioning against an impact to the maternal abdomen. o Providing a stable temperature. Promotes normal prenatal development by: o Allowing symmetric development of the fetus as body surfaces fold toward the midline. o Keeping the membranes from adhering to developing fetal parts. o Providing room and buoyancy for fetal movement.
Define each stage of labor. There are 4 stages of labor which are:
1st stage (Stage of dilation) – Includes cervical effacement and dilation (stages of dilation). It is the longest stage of labor. A Friedman curve can be used to graph labor progress. This stage differs from other stages in that it has 3 different phases. The 3 phases are: o Latent (early) Phase – Lasts from the beginning of labor until about 3 to 5 cm of cervical dilation. Its length varies among women. Despite being called latent, cervical effacement and subtle fetal position change occur during this phase, preparing for more rapid changes of active labor. The woman is usually sociable and excited during this early phase of labor. o Active Phase – The cervix dilates more rapidly as the woman enters the active phase, between about 4 cm and 6 cm. Research has demonstrated safety in a slower transition between latent and active labor than usually accepted in women in spontaneous labor. Effacement and dilation of the cervix are completed. Internal rotation occurs as the fetus descends in the pelvis during active labor. Discomfort usually increases as the pace of labor picks up. o Transition Phase – May be used to describe the intense contractions of the fetal descent and final cervical dilation, about 7 to 8 cm to complete. Bloody show
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Week 14 Discussion ~ Maternal-Child Nursing
often increases with completion of cervical dilation. Transition is a short but intense phase, with very strong contractions. The woman may have an urge to push down during contractions as the fetal presenting part reaches her pelvic floor. Leg tremors, nausea, and vomiting are common as second stage nears. The woman becomes more anxious and may feel irritable and helpless as the contractions intensify. The sociability of early labor is gone, replaced with a serious, inward focus. Her partner may be confused because actions that were helpful just a short time before now bothers her. nd 2 Stage (expulsion) – Begins with complete (10 cm) dilation and full (100%) effacement of the cervix and ends with the birth of the baby. As the fetus descends, pressure of the presenting part on the rectum and pelvic floor causes the mother to have an involuntary pushing response. She may say that she needs to have a BM or “The baby’s coming” or “I have to push.” Her voluntary pushing efforts augment involuntary uterine contractions. As the fetus descends low in the pelvis and the vulva distends with crowning of the fetal head, she may feel a sensation of stretching or splitting even if no trauma occurs. Contractions are strong, but the woman may feel more in control because she is actively completing the process by pushing with them. “Labor” describes the 2nd stage well. The woman exerts intense effort to push her baby out. Between contractions she may be oblivious to her surroundings and may appear asleep. She feels tremendous relief and excitement as the 2nd stage ends with the birth of her baby. 3rd Stage (placental) – Stage begins with the birth of the baby and ends with the expulsion of the placenta. When the infant is born, the uterine cavity becomes much smaller. The reduced size decreases the size of the placental site, causing the placenta to separate from the uterine wall. Four signs suggest placenta separation: o The uterus has a spherical shape. o The uterus rises upward in the abdomen as the placenta descends into the vagina and pushes the funds upward. o The cord descends further from the vagina. o A gush of blood appears as blood trapped behind the placenta is released. The placenta may be expelled in one of two ways. In the more common Schultze mechanism, the placenta is expelled with the shiny, fetal side first. The Duncan mechanism is less common, with the rough maternal side presenting. The uterus must contract firmly and remain contracted after the placenta is expelled to compress open vessels at the implantation site. Inadequate uterine contraction after birth may result in hemorrhage. Pain during the 3rd stage of labor results from uterine contractions and brief stretching of the cervix as the placenta passes through it. 4th Stage (physical recovery) – Lasts from the delivery of the placenta through the 1st 1 to 4 hours after birth. The vaginal drainage during this stage is called lochia rubra, which is mostly blood. Small clots may also be present.
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Week 14 Discussion ~ Maternal-Child Nursing How does fetal circulation work? The course of fetal blood circulation is from the fetal heart, to the placenta for exchange of oxygen and waste products, and back to the fetus for delivery to fetal tissues. Because the fetus does not breathe air or metabolize substance in the liver, several alterations of the post birth circulatory route are needed. Three shunts – the ductus venosus, the foramen ovale, and the ductus arteriosus – divert most circulating blood away from the lungs and liver. Oxygenated blood from the placenta enters the fetal body through the umbilical vein. About half the oxygenated venous blood goes through the liver during early pregnancy and the rest bypasses the liver and enters the inferior vena cava through the first shunt (the ductus venosus). The blood then enters the right atrium. Most of the blood passes directly into the left atrium through the second shunt, (the foramen ovale), where it mixes with the small amount of blood returning from the lungs. Blood is pumped from the left ventricle into the aorta to nourish the body. A small amount of blood from the right ventricle is circulated to the lungs to nourish the lung tissue. The rest of the blood from the right ventricle joins oxygenated blood in the aorta through the third shunt, (the ductus arteriosus). The head and upper body receive the greatest amount of oxygenated blood. During late pregnancy the liver receives 75% to 80% of the oxygenated venous blood. Define placenta Previa and abruptio placenta. What are the symptoms of each?
Placenta Previa – Implantation of the placenta in the lower uterus, near the fetal presenting part. o S/S – the classic sign of placenta Previa is the sudden onset of painless uttering bleeding in the latter half of pregnancy. Abruptio Placenta – Separation of a normally implanted placenta before the fetus is born. It occurs when there is bleeding and formation of a hematoma on the maternal side of the placenta. o S/S – There are 5 classic signs which are: Vaginal bleeding, which may not reflect the true amount of blood loss. Abdominal and low back pain that may be described as aching or dull. High uterine resting tone identified by use of an intrauterine pressure catheter. Uterine tenderness that may be localized to the site of the abruption. Other signs include back pain, nonreassuring fetal heart rate patterns, signs of hypovolemic shock, and fetal death.
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Week 14 Discussion ~ Maternal-Child Nursing References McKinney, E. (2013). Maternal-child nursing (Fourth ed.). St. Louis, Missouri: Elsevier/Saunders.
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