A new birth control pill which eliminates a woman's monthly periods gained approval from the US Food and Drug Administration Tuesday.
Unlike traditional oral contraceptives which deliver pregnancy-preventing hormones with a 21 days on and seven days off cycle, Lybrel provides a steady low dose of hormones over 28 days.
The continuous delivery of the hormones prevents the stimulation of a menstrual cycle.
This is the first time that federal regulators have signed off on the practice of eliminating the pill-free or placebo interval which stimulates a menstrual cycle.
Doctors have long allowed women to skip their periods by starting a new pack of pills on the 22nd day of their cycle rather than waiting a week to resume the hormones.
"For those women seeking contraceptive options and who are interested in putting their period on hold... Lybrel may be an appropriate choice," said Ginger Constantine, vice president for Women's Health Care at Wyeth Pharmaceuticals which developed Lybrel.
Women who want to do without their periods have had other approved options before now, however.
A pill which cuts the number of menstrual cycles down to just four a year, Seasonique, has been available for some time. And women who want to skip their periods completely could also use the hormone injection Depo Provera every three months.
The FDA warned that 41 percent of women using Lybrel in a clinical study experienced unscheduled bleeding, although these occurrences declined over time.
"Health care professionals and patients are advised that when considering the use of Lybrel, the convenience of having no scheduled menstruation should be weighed against the inconvenience of unscheduled bleeding or spotting," the FDA said.
The elimination of a regular period could also make it difficult for women to recognize if they have become pregnant, the FDA warned.
But some critics say the elimination of a period as a "lifestyle choice" could be bad for women's health.
"Menstrual suppression is unnatural," health psychologist Paula Derry wrote in an editorial in the British Medical Journal.
"A drug (that) chronically over-rides the physiological changes associated with the menstrual cycle (is) creating a hormonal environment that is not found in nature," she wrote.
Derry argues that not enough research has been done to determine the long-term impact of menstrual suppression and notes that healthy women menstruate, while illness, stress and malnourishment often lead to skipped periods.
Wyeth said 97 percent of gynecologists "thought it is safe to use oral contraceptives continuously, without a placebo phase, in the appropriate patient population," according to a Gallup survey of 205 obstetrician-gynecologists and 200 nurse practitioners.
Lybel is expected to generate 40 million dollars in sales in 2007 and 235 million dollars a year through 2010. It will be available in the United States in July.
