Progesterone supplements given to pregnant women who have had multiple miscarriages may not prevent another miscarriage, a new study found. File photo by Chaikom/Shutterstock

WASHINGTON, Nov. 26 (UPI) -- Progesterone supplements given to pregnant women who have had multiple miscarriages may not prevent another miscarriage, according to new research from the University of Birmingham.

A five-year study of 826 women with unexplained recurrent miscarriages showed those who received progesterone supplements in early pregnancy were no less likely to miscarry than those who received a placebo. The findings, published in The New England Journal of Medicine, said the same was true no matter what age, ethnicity, medical history or pregnancy history.


Progesterone supplements have been used for more than 60 years to prevent miscarriages in early pregnancy. The study found 65.8 percent of women given progesterone gave birth to a baby compared to 63.3 percent who did not take the supplement.

Professor Arri Coomarasamy, lead author of the study, acknowledged the findings may be difficult for some to accept because of the long-standing notion progesterone will help support a pregnancy.

"We had hoped, like many people, that this research would confirm progesterone as an effective treatment," she said. "Though disappointing, it does address a question that has remained unanswered since progesterone was first proposed as a treatment back in 1953. Fortunately, there are a number of other positives that we can take from the trial as a whole."

The study is being lauded as the first well-designed test of the topic. Women participated in the trial at 36 locations in Britain and nine in the Netherlands. Neither the doctors nor the patients knew whether they were receiving the supplements, in the form of vaginal suppositories, or not.

The study also found added progesterone does not cause harm to the baby or mother and it may have other uses "such as preventing miscarriage in women with early pregnancy bleeding, so it's not the end of the road," Coomarasamy said.

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