The thyroid gland is located near the front of throat and secretes the thyroxin (T4) and triiodothyronine (T3) hormones. These hormones are vital for the regulation of body’s metabolism.
The thyroid function mechanism includes a series of gland stimulations. The hypothalamus in the brain releases Thyroid Releasing Hormones (TRH), which stimulates the pituitary gland and t releases the Thyroid Stimulating Hormones (TSH). The TSH then stimulates the thyroid gland to produce thyroxin (T4) and triiodothyronine (T3), the active form of T4.
Healthy thyroid function is necessary for fertility, to conceive and to maintain a pregnancy. An under (Hypo) or over (Hyper) functioning thyroid causes an imbalance in the reproductive hormones, that affect fertility and prevent pregnancy.
Conception is more difficult for hypothyroid women due to associated ovarian dysfunction. Fertility issues in women are linked with their menstrual cycles, such as flooding, scanty periods or irregular cycles.
Hypothyroidism affects the menstrual cycle in the following ways:
Ovulation happens after the stimulation of the ovaries by Luteinizing Hormone (LH), which depends on the support of thyroid hormones. In case of imbalance in the thyroid levels, it may lead to the failure of ovulation during the menstrual period causing an anovulatory cycle making pregnancy impossible.
The second half of the menstrual cycle is known as the luteal phase. In case of a shorter luteal phase, a fertilized egg fails to get implanted and flushes out during menstruation. This is a kind of very early miscarriage which is often mistaken as a regular period.
Hypothyroidism has also been linked with the development of ovarian cysts, and such cysts may regress upon thyroid treatment.
It also causes low body temperatures which unable embryo formation, high levels of prolactin, loss of libido and other hormonal problems leading to infertility.
It is vital for women who have been struggling to conceive, have experienced 2 or more miscarriages, have family history of thyroid or suspect a thyroid issue to consult a gynecologist and get proper testing of complete thyroid profile done prior to trying to conceive. Maintaining a good thyroid health as per guidance and regular monitoring can help to sustain a healthy pregnancy.