Contraceptive Pills Halve Size of Women’s Ovaries

A new study has found that birth control pills can reduce women’s ovaries upward of 50% in size, but the that the ovaries appear to return to normal after cessation.

Researchers at Rigshospitalet (Copenhagen, Denmark) and Copenhagen University (Denmark) conducted a study involving 833 women, aged 19–46, of whom almost 30% took contraceptive pills. The women underwent two tests to indicate how their ovaries were aging; anti-Muthe higher (AMH) blood levels, and the AFC test, which uses ultrasound scanning of antral follicles—containing immature eggs that released each month during menstruation—to indicate how many eggs from the ovaries are recruited for ovulation, a measure of fertility.

The results of the study showed that for young women (19–29.9 years of age), the ovaries were reduced by 52%, compared with women who were not on the pill. The result of the AMH test was 19% lower for women who took birth control pills, while the result of the AFC test was reduced by 16%, compared with women who did not take birth control pills. The study was presented at the European Society of Human Reproduction and Embryology (ESHRE) fertility conference, held during July 2014, in Munich (Germany).

“Young women typically have well-developed and well-functioning ovaries, while women approaching their menopause have smaller ovaries with reduced egg production," said lead author and study presenter Kathrine Birch Petersen, MD. “We noticed that a number of young women who took birth control pills had ovaries that looked like they were approaching the menopause. That the size of the ovaries is reduced so much is quite convincing.”

The researchers stressed that the results of the study do not apply to women who use contraceptive mini-pills, hormone spirals, and contraceptive implants.

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Rigshospitalet
Copenhagen University