Ever wondered how the body releases an egg every month or how the uterus wall thickens and thins at different times of the month? It is the work of the body’s chemical messengers – hormones, which regulate the various processes involved in preparing the body for fertilization.
Hormones and fertility
A delicate balance of various hormones involved in regulating the reproductive organs enables and maintains fertility. These hormones control changes like release of egg from ovary (ovulation) and thickening of the uterine wall lining (endometrium). Infertility may result if this balance is disturbed.
Let’s take a look at the different hormones involved in the reproductive system:
- Follicle-stimulating hormone (FSH): Released by the pituitary gland in the brain, FSH controls the menstrual cycle and egg production. Its levels indicate ovarian function and egg quality.
- Estradiol: Estradiol is an important form of oestrogen; abnormal levels decrease the response to ovulation.
- Luteinizing hormone (LH): LH, released by the pituitary gland, stimulates the ovaries to release egg and also initiates the production of progesterone (that prepares the uterus to receive a fertilised egg). LH levels spike right before ovulation.
- Progesterone: It is produced in the ovaries in response to LH right after ovulation (generally 12-16 days after first day of last period). Progesterone is an important hormone for allowing a fertilised egg to stay and grow in the uterus.
- Thyroid hormones: These interact with oestrogen and progesterone to maintain the normal functioning of the ovaries and ovulation.
Infertility and hormonal issues
Some of the common infertility problems associated with imbalances in hormone levels and their interactions include:
- Anovulation (Failure to produce mature eggs) – For fertilisation to occur and pregnancy to take place, it is important for a woman’s ovaries to release an egg (ovulation). Under optimal conditions, one egg is released every month. However, in a condition known as polycystic ovary syndrome (PCOS), ovulation is rare or absent, and is characterised by symptoms like amenorrhoea (no period), hirsutism, anovulation and infertility. The underlying cause of anovulation is a reduced production of FSH, and normal or elevated levels of LH, oestrogen and testosterone. The low levels of FSH prevent proper development of the ovarian follicles; ovarian cysts are common.
- Improper functioning of hypothalamus – The hypothalamus sends a signal to the pituitary gland, which then stimulates the ovaries through FSH and LH to mature eggs. Ovarian failure and infertility results if the hypothalamus does not function properly.
- Malfunction of the pituitary gland – Physical injury, tumour or a chemical imbalance in the pituitary gland causes the gland to release too little or too much of FSH and LH. This hampers ovulation in the ovaries.
- Role of thyroid glands – Hyperthyroidism (too much thyroid hormone) or hypothyroidism (too little thyroid hormone) can impair the balance of reproductive hormones and lead to thyroid-related fertility problems like irregular menstruation, ovulation disorder, trouble conceiving or miscarriage. Thyroid disorder is common among women in the reproductive age, and must be checked for if a woman is having trouble getting pregnant or if thyroid disease runs in the family.
“Reproductive Hormones,” Resolve.org, The National Infertility Association, https://www.resolve.org/diagnosis-management/infertility-diagnosis/reproductive-hormones.html
“The role of hormones in fertility,” University of Colorado Advanced Reproductive Medicine https://arm.coloradowomenshealth.com/resources/learn/infertility/causes-female/hormones/
“What Causes Female Infertility?” Stanford.edu, https://web.stanford.edu/class/siw198q/websites/reprotech/New%20Ways%20of%20Making%20Babies/Causefem.htm
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