40w LaterGuide

Many hormones work together to regulate ovulation and support conception. An imbalance in some of these hormones can interfere with ovulation and make it more difficult to become pregnant.

Hormone levels can be evaluated through blood tests. Some reproductive hormones, such as follicle-stimulating hormone (FSH), luteinizing hormone (LH), and estradiol (E2), are often measured early in the menstrual cycle because their levels change throughout the cycle.

Common hormones evaluated during a fertility assessment include thyroid hormones and thyroid-stimulating hormone (TSH), prolactin, FSH, LH, and estradiol.

1) Thyroid hormones

The thyroid gland produces thyroid hormones, which play important roles in metabolism, body temperature regulation, and many other functions. TSH, which is produced by the pituitary gland, regulates the production of thyroid hormones.

Both an overactive thyroid (hyperthyroidism) and an underactive thyroid (hypothyroidism) can affect reproductive health. In particular, untreated thyroid dysfunction may interfere with ovulation and pregnancy and can be associated with adverse pregnancy outcomes.

Treatment depends on the type and severity of the thyroid disorder. Hypothyroidism is generally treated with levothyroxine, while hyperthyroidism may require antithyroid medication. The choice of medication can differ when pregnancy is being planned or during pregnancy, so treatment should be discussed with a healthcare professional.

Sometimes thyroid hormone levels are normal but TSH is elevated. This is known as subclinical hypothyroidism. Whether treatment is necessary depends on factors such as the TSH level, thyroid antibody status, fertility treatment plans, and individual medical history.

2) Prolactin

Prolactin is a hormone produced by the pituitary gland that stimulates breast milk production after childbirth. When prolactin levels are abnormally high outside pregnancy and breastfeeding, they can interfere with the hormones involved in ovulation, sometimes causing irregular or absent periods and making conception more difficult.

This condition is called hyperprolactinemia. There are many possible causes, including certain medications, thyroid disorders, and conditions affecting the pituitary gland. If an abnormal result is found, additional testing may be needed to determine the cause. Do not stop any prescribed medication before testing unless instructed to do so by your healthcare provider.

When treatment is necessary, medications such as cabergoline or bromocriptine may be used to lower prolactin levels. Treatment depends on the underlying cause and individual circumstances.

3) Reproductive hormones

FSH, LH, and estradiol (E2) are commonly evaluated as part of a fertility assessment. Because their levels fluctuate throughout the menstrual cycle, they are often measured during the early follicular phase, usually around days 2–4 of the menstrual cycle when clinically appropriate.

FSH helps stimulate the growth of ovarian follicles, while LH plays an important role in ovulation. Estradiol is produced mainly by developing ovarian follicles and changes throughout the menstrual cycle.

These hormone results should not be interpreted based on a single value alone. Age, menstrual cycle pattern, ovarian reserve, ultrasound findings, and other hormone tests may all need to be considered together.

For example, unusually low levels of reproductive hormones can occur when signaling from the hypothalamus or pituitary gland is reduced, which may interfere with normal follicle development and ovulation. This can sometimes occur with significant weight loss, insufficient energy intake, excessive exercise, or other medical conditions.

An elevated LH level relative to FSH may sometimes be seen in women with polycystic ovary syndrome (PCOS), but the LH-to-FSH ratio alone cannot diagnose PCOS.

If a hormonal problem affecting ovulation is identified, treatment can be tailored to the underlying cause. Depending on the condition, this may include treating an underlying thyroid or prolactin disorder or using medications to induce ovulation.