Skipping Periods: The Pros, the Cons, the Science

Do the benefits of suppressing a woman's menstrual cycle outweigh potential risks? Scientific evidence so far suggests they may. Dissenters, however, say it's too early to tell.

While Seasonale is the first extended-cycle FDA-approved oral contraceptive on the market, it's not the first contraceptive to halt menstrual flow. Depo Provera, an injectable hormone on the market since 1992, has a similar effect for half of its users. The progestin-only injection, administered once every three months, is associated with side effects including weight gain and depression. These problems have not been reported with Seasonale.

Because Seasonale's components -- synthetic progesterone (.15 micrograms of levonorgestrel) and estrogen (.3 micrograms of ethinyl estradiol) -- are the same as in Nordette, an older birth control pill, the FDA required the product undergo only one year of a clinical trial, instead of two (required for pills with new components). The trial, which involved about 1,400 women between the ages of 18 and 40, found risks and benefits similar to those associated with traditional oral contraceptives.

Birth control pills, on the market since the 1960s, are currently used by more than 18 million women, according to the National Institututes of Health.

The pill has been shown to reduce risk for some conditions, including ovarian and endometrial cancer. Studies have also shown that they can increase a woman's risk for other diseases, such as strokes and liver cancer.

But Seasonale delivers nine more weeks' worth of hormones per year than Nordette, because the new product follows a 84/7 regimen (84 days on the pill, followed by 7 days off) instead of Nordette's 21/7 schedule. For that reason, some health professionals say more long-term safety data is needed.

"The first rule of medicine is do no harm," said Lawrence Nelson, head of the National Institute of Child Health and Human Development's unit on gynecologic endocrinology. "We are talking about giving more of a drug to go beyond protecting from pregnancy to remove menstrual cycle out of convenience. This may have adverse effects we don't know about."

Susan Rako, a Massachusetts psychiatrist who wrote the book "No More Periods? The Risks of Menstrual Suppression" (Harmony Books, 2003), calls Seasonale "an uncontrollable experiment," all of whose effects won't be known for at least 30 years.

Barr Pharmaceuticals -- and many ob-gyns -- dispute that assessment. "The chemical compounds we are using are at least 25 years old; they have been tested and are tried and true," said Carole Ben-Maimon, president of research for Barr.

Here is a summary of the pros and cons of using Seasonale.