I first learned about anovulation from a friend in high school who said she had only one period a year. My other friends and I were in awe and a bit jealous that she only had to worry about pads or tampons once a year. But we also wondered if it might affect her ability to have kids, although motherhood seemed so far away that we didn’t think about it for long. Years later, I understand more how common this condition is and what it means for a woman’s health and fertility.
Ovulation is when the ovary develops an egg and releases it to travel through the fallopian tube to the uterus. Anovulation is the lack of ovulation and is a sign of abnormal hormone levels. One symptom of the condition is irregular, few or no periods.
When a woman has regular periods, it is a sign that hormone levels are going through a normal cycle. This requires communication between the hypothalamus and pituitary glands in your brain, and your ovaries. At the beginning of a cycle, falling progesterone and estrogen levels in the blood stimulate the pituitary gland to send out its own set of hormones. These pituitary hormones stimulate the ovary to produce more estrogen, develop a new egg and release it to the uterus. The cells around the developing egg send out higher levels of estrogen and progesterone into the blood. After the egg is released the surrounding cells stop functioning, progesterone and estrogen levels fall, and the cycle starts all over again.
So what is it about infrequent and irregular periods that is unhealthy? When periods are infrequent or don't occur, the explanation for some women is that their estrogen levels tend to remain low, increasing your risk of osteoporosis, weak bones that can break easily. It is especially important for women before the age of 30 to have normal levels of estrogen because those are your peak bone-building years.
Girls and women who have irregular periods should be evaluated for health conditions that could be responsible for altered hormone levels. A common cause of infrequent and irregular periods is polycystic ovarian syndrome (PCOS). Women with this disorder often have other medical conditions including obesity, elevated blood sugars and higher male hormone levels (testosterone) that can lead to acne and hirsutism — the development of coarse hair on the face, back, chest or lower abdomen. Insulin resistance is a key factor in PCOS-related medical problems, and resistance to insulin appears to play an important role in why women with this syndrome don't ovulate normally.
Other conditions that can interfere with ovulation include:
- An underactive thyroid gland and low thyroid hormone levels (hypothyroidism)
- High prolactin levels (a hormone normally produced during breastfeeding) released from a small tumor in the pituitary gland or caused by some medications
- Long and intense exercising, such as is typical with competitive gymnasts and marathon runners
- Very low body mass index, such as ballerinas who strive for extreme thinness or young women with anorexia
The approach to infrequent periods and abnormal pituitary-ovary communication is to first look for underlying medical conditions. Correcting the abnormality will probably restore regular periods. For example, women with PCOS who are treated with medications that improve insulin sensitivity increase their likelihood of ovulating and becoming pregnant. When no correctable medical condition is found, women can take birth control pills to raise estrogen for preservation of bone density.
Anovulation is a common cause of infertility because the number of eggs released each year can be very few or none. Fortunately, medical research in this field has been robust and has provided doctors with medications that can help many women who are anovulatory become pregnant. For example, clomiphene is a medication commonly used to help your pituitary gland produce more stimulating hormone for the ovary. Or the stimulating hormone itself may be given directly in an injectable form.
When I see women in my practice who have irregular or few periods, it sometimes is something they have experienced for years or since adolescence without telling anyone and without being evaluated. It’s not something most girls learn about from each other or in health education class. So if you learn about a friend or family member with irregular periods, mention the important health reasons why she should have this evaluated and treated.
Alice Y. Chang, M.D. is a former instructor in medicine at Harvard Medical School. She is currently associated with University of Texas Southwestern Medical Center. Her clinical interests and experience are in the fields of primary care, women's health, hospital-based medicine and patient education.