Understanding our reproductive hormones

HORMONES ARE CHEMICALS WHICH CONTROL AND REGULATE OUR BIOLOGICAL PROCESSES – AND THEREFORE MANY ASPECTS OF OUR HEALTH. THIS ARTICLE EXPLORES THE KEY FEMALE REPRODUCTIVE HORMONES: WHAT THEY DO, AND THE EXTENT TO WHICH THEY CAN IMPACT ON OUR PHYSICAL, MENTAL, AND EMOTIONAL HEALTH.

Hormones are chemical messengers produced by glands and organs in the endocrine system. They manage growth and development, metabolism, mood, and reproduction, and are therefore critical to the functioning of our bodies.

There are over 50 hormones; you may have heard of insulin, adrenaline, melatonin, and thyroxine, for example. But quite a few are involved in reproduction, and the main female hormones are oestrogen, progesterone, and testosterone.1

Female reproductive hormones

Oestrogen is produced primarily in the ovaries and plays a key role in the development and regulation of the reproductive organs and secondary sex characteristics (such as pubic hair).2 It also helps maintain healthy bones and regulates cholesterol levels. Oestrogen has three major forms:3

• Oestrone, which is made after menopause4

• Oestradiol, the most potent form, which is made during the reproductive years

• Oestriol, the primary form during pregnancy

Progesterone is produced mainly in the ovaries and the adrenal glands, and is essential for maintaining menstruation and healthy pregnancy.5 Testosterone is not an exclusively male hormone. In women, it is produced in the ovaries, adrenal glands and peripheral tissues and is responsible for maintaining muscle mass, bone density and libido.6

The menstrual cycle

This is a complex process, regulated by reproductive hormones. It is divided into four phases,7 each characterised by different hormone levels and physical changes in the body:

• The follicular phase begins on the first day of menstruation. The pituitary gland produces follicle-stimulating hormone (FSH), which stimulates the growth of follicles and eggs in the ovaries. As they grow, they in turn produce increasing amounts of oestrogen. This oestrogen causes the lining of the uterus (the endometrium) to thicken and become blood-rich, so that any fertilised egg could implant there and develop. The oestrogen also triggers the release of luteinising hormone, which is needed in the next phase. This follicular phase lasts around 14 days.

• The ovulatory phase lasts one day. Luteinising hormone causes the biggest follicle to release its egg – this is called ovulation. The egg travels down the fallopian tube towards the uterus. If it is fertilised by a sperm, the egg implants in the thickened uterine wall and pregnancy begins. If fertilisation doesn't occur, then both the egg and the uterine lining are shed during the final menstrual phase.

• The luteal phase begins after ovulation and lasts around 14 days. The follicle which released the egg transforms into a corpus luteum, a small temporary cyst which produces progesterone. Like oestrogen, progesterone helps thicken the uterine wall in preparation for pregnancy, but it also inhibits contractions – thereby preventing miscarriage – and stops the body’s immune system from rejecting the foetus as a perceived foreign body. If pregnancy doesn’t occur, the corpus luteum disintegrates and hormone levels drop, triggering the start of the next phase.

• The menstrual phase is the shedding of the uterine lining and occurs approximately every 28 days. It lasts anywhere from three to seven days and involves the discharge of blood and other materials from the uterus. During this phase, hormone levels are low, and the body is beginning to prepare for the whole cycle to repeat.

Hormonal imbalances

Hormone imbalances can cause a variety of health problems in women:

Low oestrogen can lead to irregular periods, hot flushes, and vaginal dryness.2 It can also increase the risk of osteoporosis, where bones become weak and brittle. High levels of oestrogen, on the other hand, can increase the risk of breast and uterine cancer.8

Low progesterone can cause irregular periods, heavy bleeding, and mood swings, as well as increased risk of miscarriage and pre-term birth.9

Low testosterone can lead to decreased sex drive, irregular periods, acne, and unwanted hair growth.6

High follicle-stimulating hormone can damage the ovaries and reduce the chances of getting pregnant.10

Low luteinising hormone can also cause fertility problems.10

Hormone imbalances can have various underlying causes, from stress and poor nutrition to certain medical conditions. While oestrogen levels fluctuate throughout life, particularly during puberty, pregnancy, and menopause, you should consult your healthcare provider if you experience any of the above symptoms.11

Common reproductive hormone therapies

Birth control pills: These contain synthetic versions of oestrogen and progesterone, and they can prevent ovulation (thus avoiding pregnancy) and regulate the menstrual cycle. They can also improve acne and reduce the risk of ovarian and endometrial (uterine) cancer. However, they can have side effects such as nausea, headaches and mood changes.12 You should discuss the risks and benefits with a healthcare provider, such as your local Blooms The Chemist Pharmacist.

Menopausal hormone therapy: This is used to alleviate symptoms of menopause, the process by which a woman’s fertility and reproductive cycle come to an end, typically between the ages of 45 and 55. During menopause, oestrogen and progesterone levels decrease, leading to over 30 symptoms – common ones include hot flushes, night sweats, dry skin and mood changes.3 MHT contains synthetic versions of oestrogen and/or progesterone to relieve these symptoms. However, MHT may not be appropriate for everyone, such as those with a family history of breast or ovarian cancer, a history of blood clots, or those with hypotension. Consult your doctor to learn if this may be appropriate for you.

Lifestyle changes can also help to regulate hormones and improve overall health. A balanced diet rich in fruits, vegetables, whole grains, and lean protein can help to regulate hormone levels and prevent chronic diseases such as heart disease and diabetes. Regular exercise can also help, along with stress management techniques such as yoga, meditation, and getting enough sleep.13

1How do female sex hormones affect menstruation, pregnancy, and other functions?: https://www.healthline.com/health/female-sex-hormones

2Oestrogen: https://www.healthdirect.gov.au/oestrogen

3Estrogen: https://my.clevelandclinic.org/health/body/22353-estrogen

4Oestrone: https://www.yourhormones.info/hormones/oestrone/

5Physiology, progesterone: https://www.ncbi.nlm.nih.gov/books/NBK558960/

6Testosterone and women; https://www.menopause.org.au/health-info/resources/ testosterone-and-women

7The normal menstrual cycle and the control of ovulation: https://www.ncbi.nlm.nih. gov/books/NBK279054/

8Breast cancer and oestrogen: https://www.betterhealth.vic.gov.au/health/ conditionsandtreatments/breast-cancer-and-oestrogen

9Everything you need to know about progesterone: https://www.healthline.com/health/ progesterone-function

1010 warning signs you may have a hormonal imbalance : https://hormonehealth. co.uk/10-warning-signs-you-may-have-a-hormonal-imbalance-and-what-to-do-about-it

11Hormones: a balancing act?; https://www.jeanhailes.org.au/news/hormones-abalancing-act

12Contraceptive pills: https://www.thewomens.org.au/health-information/ contraception/contraceptive-pills

13Effect of physical activity on sex hormones in women: https://www.ncbi.nlm.nih.gov/ pmc/articles/PMC4635995/