The new birth control pill Lybrel is the first oral contraceptive designed to be taken 365 days a year with no pill-free intervals. Women who use Lybrel don’t have regular periods, although they may have breakthrough bleeding. There are risks and benefits to suppressing menstruation, reports the September 2007 issue of Harvard Women’s Health Watch.

The idea of preventing periods is not completely new. Conventional oral contraceptives also stop periods if they are taken continuously, and a clinician may suggest this approach to enable a woman to skip her period at an inconvenient time, such as during her honeymoon. The notion of suppressing periods over a longer term has become increasingly attractive, partly because this strategy has helped with treating endometriosis and managing the hormonal swings of perimenopause.

There’s some justification for reducing the number of periods or eliminating them altogether. For some women, eliminating periods can mean avoiding cramps, mood swings, headaches, and heavy bleeding that can cause anemia. On the other hand, many women are uncomfortable with the notion of not having periods. One concern about Lybrel is that if it fails, a woman may not know she is pregnant.

The Harvard Women’s Health Watch notes that there are no long-term safety data on Lybrel, but its risks are thought to be similar to conventional oral contraceptives—an increased incidence of blood clots, heart attacks, and stroke, especially in smokers. On the plus side, birth control pills appear to lower the risk of ovarian and endometrial cancers; Lybrel might do the same. But the effects of taking Lybrel for more than a year are unknown. The use of continuous birth control has to be considered largely uncharted territory.