Hypothyroidism occurs when the thyroid gland is not producing as much thyroid hormones. It is common in women of reproductive age. In more severe cases, the body’s metabolism slows, causing mental and physical sluggishness and a variety of other symptoms including a failure to ovulate or failure to ovulate regularly. This, in turn, causes a woman’s periods to occur less frequently (oligomenorrhea) or to stop completely (amenorrhea).
The most common cause of hypothyroidism is the presence of elevated levels of antibodies directed to the thyroid gland. It is possible to have elevated levels of anti-thyroid antibodies and still have a normally functioning thyroid gland. In this case, it is important to monitor the thyroid hormones on a regular basis. They should also be thoroughly checked during pregnancy and after delivery since a woman may be more prone to thyroid malfunction then.
High prolactin levels (hyperprolactinemia) may cause infertility. Women who are not pregnant and are not breastfeeding should have low levels of prolactin. If a non-pregnant woman has abnormally high levels of prolactin, it may cause difficulty in becoming pregnant.
Prolactin may cause infertility in several different ways. Prolactin may stop a woman from ovulating, causing a stop in a woman’s menstrual cycle. In less severe cases, high prolactin levels may only disrupt ovulation once in a while, resulting in intermittent ovulation or ovulation that takes a long time to occur. Women in this category may experience infrequent or irregular periods. Women with the mildest cases involving high prolactin levels may ovulate regularly but not produce enough of the hormone progesterone after ovulation (also commonly known as the luteal phase defect). Deficiency in the amount of progesterone produced after ovulation may result in a uterine lining that is less able to have an embryo implant.