Ovulation disorders are a common cause of infertility and are present in up to 30% of cases. Every month a normally ovulating female recruits eggs that develop to maturity and are released according to precise timing governed by hormone relationships in the menstrual cycle. Lack of ovulation is termed "anovulation" and irregular ovulation is termed "oligoovulation".

The fertility specialist will order numerous tests to assess ovulation that may include FSH (follicle stimulating hormone), LH (luteinizing hormone), estrogen, progesterone, androgens, thyroid and adrenal tests. Other tests might include an ultrasound exam to visualize the ovaries and a clomiphene citrate challenge test.

In order to understand ovulatory disorders, it is necessary to have a basic understanding of the various hormone relationships involved in the hypothalamic-pituitary-adrenal axis (HPA axis). The hypothalamus is a small gland located at the base of the brain, which can be thought of as a "thermostat". It releases gonadotropin releasing hormone (GnRH), which travels to the pituitary where it stimulates the production of FSH and LH.

The hypothalamus signals the pituitary to increase production of FSH during the first few days of the menstrual cycle. FSH is responsible for stimulating the recruitment of ovarian follicles, each of which contains an egg, and supporting their growth. As healthy follicles mature, they begin to produce estrogen, which helps to stimulate the growth of the endometrium (lining of the uterus). The endometrium must thicken to accept and support the growth of an embryo.

Estrogen levels are monitored by a part of the brain called the hypothalamus and as they increase, the hypothalamus signals the pituitary to reduce production of FSH. Once the hormone levels indicate that the follicles are mature, the hypothalamus signals the pituitary to release a surge of luteinizing hormone (LH). The spike in LH levels triggers ovulation approximately 36 hours after the surge. The ovaries begin to produce progesterone, which also supports the development of the endometrium. Rising levels of human chorionic gonadotropin (hCG), produced by the placenta, are an indication of pregnancy. If pregnancy does not occur, the lining of the endometrium breaks down and is released during menstruation.

There are many causes of oligoovulation (irregular ovulation) and anovulation (no ovulation) including:

Ovarian failure as a Cause of Ovulation Failure- Women are born with all the eggs they will have for a lifetime and one is usually ovulated during each monthly menstrual cycle. As women age, infertility increases as ovarian function begins to decline until the menopause, where no more eggs are released and FSH levels are very high. Ovarian failure means that the ovaries cannot produce eggs that will normally fertilize and develop. Day 3 FSH levels are elevated in these patients and response to the clomiphene citrate challenge test is abnormal. Ovarian failure may occur early in some women and is discussed in detail in our "Age and Fertility" section. These women are often candidates for our donor egg program.
Polycystic ovarian syndrome, PCOS- a common condition characterized by elevated androgens (male hormone), reduced insulin sensitivity, and numerous cysts on the ovary. Elevated androgens can lead to oligoovulation.
Thyroid dysfunction- Abnormally high (hyperthyroidism) or low (hypothyroidism) levels of thyroid hormone can cause irregular ovulation thought to be due to the high levels of estrogen associated with these conditions.
Hyperprolactinemia - Prolactin is responsible for breast milk production in pregnant women. Elevated levels of the hormone, prolactin, can lead to ovulatory disorders and infertility. Elevated levels in the absence of pregnancy cause irregular ovulation by reducing the levels of FSH and LH.
Excessive exercise, stress, and anorexia can lead to irregular ovulation.
Adrenal dysfunction- Androgens are produced by the adrenal glands and abnormally elevated levels lead to oligoovulation. Increased androgens are associated with elevated levels of prolactin, and/or tumors on the ovary, pituitary, or adrenal gland.
Unexplained- Sometimes eggs will not fertilize and develop into health embryos for unexplained reasons. In many cases, these couples achieve pregnancy with donor egg IVF.
Irregular ovulation can usually be treated effectively with medications such as Clomid, Metformin, Bromocriptine, or FSH unless it is due to reduced ovarian reserve or ovarian failure. The best option for patients with ovarian failure is IVF using donor eggs.

Other Fertility Links