Couples' Caffeine Use Linked to Higher Risk of Miscarriage
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Couples who wish to get pregnant may want to avoid caffeine because it's associated with an increased risk of miscarriage, a new study from the National Institutes of Health (NIH) suggests.

For women, drinking more than two caffeinated drinks daily before getting pregnant was associated with a 74 percent higher risk of a miscarriage, according to the study published today (March 24) in the journal Fertility and Sterility. 

But women's caffeine consumption wasn't the only factor: Among couples in which the male partner drank more than two caffeinated beverages daily before conception, there was a 73 percent higher risk of a miscarriage, according to the study. [6 Myths About Miscarriage]

"Our findings indicate that the male partner matters, too," Germaine Buck Louis, the director of Intramural Population Health Research at the National Institute of Child Health and Development and lead author on the study, said in a statement. "Male pre-conception consumption of caffeinated beverages was just as strongly associated with pregnancy loss as females'," Buck Louis said.

The study included 501 couples in Michigan and Texas who had stopped using contraception and were trying to become pregnant. The couples were instructed to keep daily journals of their lifestyle behaviors, including smoking cigarettes and drinking alcohol and caffeinated beverages, according to the study. Couples who got pregnant within a year continued in the study until they gave birth or experienced a miscarriage, according to the study.

Of the 344 couples who became pregnant, 98 experienced a miscarriage, according to the study. Women 35 and older were nearly twice as likely to miscarry as women younger than 35, according to the study.

In addition to the caffeine findings, the researchers also found that women who took a daily multivitamin before and during pregnancy were less likely to have a miscarriage. Women who took a daily multivitamin before getting pregnant were 55 percent less likely to miscarry, according to the study. And women who continued to take the multivitamin during early pregnancy had a 79 percent lower miscarriage risk, according to the study.

The protective effect from the multivitamin may come from the folate and vitamin B6 found in a multivitamin, both of which have been linked to decreased risk of miscarriage, according to the study.

The study only showed an association between caffeine intake and miscarriage, and did not prove cause and effect. Previous studies have shown similar results, although the potential mechanism is still unknown, according to the study.

The authors did note, however, that the findings of the study do not necessarily mean that drinking decaf instead of regular coffee is safer, as the study did not include information on decaffeinated drinks, they wrote. 

Couples may want to limit their caffeine intake to fewer than three daily beverages, and women should continue to to be advised to take daily multivitamins before and during pregnancy, the researchers wrote in their conclusion.  

Follow Sara G. Miller on Twitter @SaraGMiller. Follow Live Science @livescience, Facebook & Google+. Originally published on Live Science.