Skipping Periods on the Pill

B O S T O N, Oct. 31 -- Skipping a menstrual period is unusual for many women. But experts say women taking birth control pills may not need a monthly period.

A study appearing today in the journal Obstetrics and Gynecology examines what happens when women extend their menstrual cycles using oral contraceptives.

The study compared annual expenditure on feminine hygiene products and episodes of spotting or breakthrough bleeding in 24 women who followed a typical 28-day cycle with 21 active pills and seven placebos, vs. 29 women on an extended 49-day cycle.

Subjects following the extended cycle skipped over the seven days of placebo pills included in every birth-control pill pack that normally allow for menstruation-like "withdrawal bleeding." Instead, these women took 42 active pills continuously, only then taking the placebos for seven days. The women, all in Seattle, were followed for 336 days, which allowed for study of numerous menstrual cycles in both groups.

Women who followed the 49-day regimen spent significantly less money every year on hygiene products and showed no increase in breakthrough bleeding compared to those following the 28-day regimen.

In fact, cycle lengthening was so well-received by subjects that after the study was concluded, more than half of the women on the extended cycle wished to continue with that regimen, and more than 16 percent of those on the 28-day cycle wanted to switch to the extended schedule.

According to Dr. David Grimes, clinical professor in the department of obstetrics and gynecology at the University of North Carolina School of Medicine, and a leading expert on birth control, there has until now been little scientific evidence collected on the subject of lengthening menstrual periods.

While a growing number of experts accept the idea of menstrual suppression in pill-using women, some would like to see further scientific evidence before signing on, says Grimes.

Periods on the Pill

"Withdrawal bleeding" occurs when a woman's hormone levels drop because she starts taking the seven days worth of placebo pills.