QUICK STUDY : A weekly digest of new research on major health topics

INFERTILITY

Increased ovulation may not guarantee pregnancy.

· THE QUESTION Various drugs have been shown to stimulate ovulation in women with one of the most common causes of infertility: polycystic ovary syndrome, or PCOS. The condition occurs when a woman produces higher-than-normal levels of the male hormone androgen, disrupting the development and release of eggs during ovulation and causing the formation of cysts on the ovaries. Are pregnancy and birth rates comparable for women taking these drugs?

· THIS STUDY randomly assigned 626 infertile women with PCOS to take clomiphene, metformin or both daily for up to six months, stopping the medication once a pregnancy was confirmed. Participants were asked to have intercourse every two to three days. More women who took both drugs ovulated successfully than did the others (60 percent vs. 49 percent on clomiphene and 29 percent on metformin), but this did not translate to comparably higher pregnancy and birth rates. The birth rate among women who took clomiphene alone or the combination was three times greater than for those who took just metformin (about 22 percent vs. 7 percent). Also, the 115 pregnancies among women who took clomiphene, alone or in combination, included four pairs of twins and one set of triplets; the 18 pregnancies in the metformin-only group included no multiple births. Gastrointestinal symptoms were more common among women taking metformin; hot flashes were more frequent when clomiphene was taken.

· WHO MAY BE AFFECTED BY THESE FINDINGS? Infertile women with PCOS, which affects an estimated 5 to 10 percent of women of reproductive age in the United States.

· CAVEATS The study did not included data on other medications the women may have taken during pregnancy. Participants were given an extended-release form of metformin; whether the immediate-release version would have produced different results is unclear. Multiple births pose increased risks to mothers and infants. Metformin was provided by Bristol-Myers Squibb; one of the 15 primary authors reported an equity interest in the company.

· FIND THIS STUDY Feb. 8 issue of the New England Journal of Medicine; abstract available online at http://www.nejm.org.