Chicago—Natural progesterone treatment before pregnancy could be the solution for women who have had two or more unexplained miscarriages.

That’s according to a study published recently in published in Fertility and Sterility, the international journal of the American Society for Reproductive Medicine.

University of Illinois–led researchers point out that progesterone has been used for infertility for more than 50 years because it helps stabilize the endometrium, yet has not been adequately studied in women who become pregnant easily but have difficulty maintaining pregnancy.

“Recurrent pregnancy loss is a heartbreaking challenge for as many as one in 20 women, although it is not often openly discussed,” explained Mary Stephenson, MD, director of the recurrent pregnancy loss program at the University of Illinois Hospital & Health Sciences System. “And while we know a lot about sporadic miscarriage, which is a natural mechanism of the body when there is a chromosome error at conception, we do not know nearly enough about unexplained recurrent pregnancy loss.”

The study enrolled 100 consecutive women at the health center with two or more unexplained miscarriages of less than 10 weeks from July 2004 to October 2008. Women with abnormal levels of nCyclinE (nuclear cyclin E), a molecular marker for the health of the endometrium determined by biopsy, were prescribed progesterone during the second half of their menstrual cycle, when the uterine lining matures in preparation for a possible pregnancy.

Of the 452 prior pregnancies, 85% were miscarriages. Results indicate that 59 of the participants had elevated cyclin E, and 44 of the women had no other endometrial findings, such as endometritis. Repeat biopsy on 24 of the 44 after initiating progesterone appeared to lead to 92% correction or improvement.  

In fact, researchers found that natural progesterone, administered vaginally, led to a higher birth rate. Over two-thirds of pregnancies were successful in women who received progesterone, compared with barely half in women who did not receive the hormone.

“We are very pleased to find that these results reinforce the evidence that progesterone could be a very beneficial, inexpensive and safe treatment for many women with a history of recurrent pregnancy loss,” Stephenson said.

While noting that increased nuclear cyclin E in endometrial glands in mid-luteal phase can be downregulated with progesterone and that progesterone might improve subsequent pregnancy outcomes, study authors call for a randomized clinical trial to confirm their findings.

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