As women get older, it's harder for them to get pregnant. Researchers at Cornell University looked at whether older women were more likely to miscarry pregnancies that resulted from in vitro fertilization.

What the researchers wanted to know: What is the miscarriage rate for women having in vitro fertilization (IVF) treatment?

What they did: The researchers read records of IVF pregnancies at a hospital in New York from 1991 to 1996, looking for women who miscarried after doctors had first detected the fetus's heartbeat. Out of the 2,014 pregnancies examined, 233, or about 12 percent, were lost.

What they found: Older women had a higher chance of miscarrying. For women under 30, the chance was 5.3 percent, but women 40 and over had a whopping 22.2 percent chance of losing their pregnancy. The risk was 7.6 percent for women ages 30 to 34 and 12.8 percent for women ages 35 to 39. Women who were carrying only one fetus had, unsurprisingly, a higher risk of losing the entire pregnancy than women who had multiple fetuses. Women with just one fetus were also more likely to be older. (But older women with just one fetus were still more likely to lose the pregnancy than younger women with a singleton.)

What this means to you: For women and their doctors considering IVF—the study helps define the risk of losing a pregnancy and could help with the decision about how many embryos to implant.

Caveats: The study did not include women who used donor eggs or frozen embryos.

Find out more: The American Reproductive Medicine Society publishes Fertility and Sterility, the journal this study was published in; see their resources for patients.

Read the article: Spandorfer, S.D. et al. Relationship Between Maternal Age and Aneuploidy in In Vitro Fertilization Pregnancy Loss. Fertility and Sterility. May 2004, vol. 81, pp. 1265-1269.