A new study conducted by the National Institutes of Health (NIH) suggests couples who consume more than two caffeinated beverages daily in the weeks leading up to conception may have an increased risk of miscarriage. The research, conducted with authors at the Ohio State University, similarly found women who drank more than two daily caffeinated beverages during the first seven weeks of pregnancy saw an increased miscarriage risk. Previous studies have drawn similar links, but researchers hadn’t been able to single out caffeine as a particular culprit.

“Our findings provide useful information for couples who are planning a pregnancy and who would like to minimize their risk for early pregnancy loss,” first study author Dr. Germaine Buck Louis, director of the Division of Intramural Population Health Research at NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development, said in a news release.

The research, published Thursday in the journal Fertility and Sterility, also found that women who took a daily multivitamin before conception and through early pregnancy were less likely to miscarry than women who did not.

Researchers compared lifestyle factors among 344 couples with a singleton pregnancy from the weeks before they conceived through the seventh week of pregnancy. They drew data from a different longitudinal study of 501 couples from four counties in Michigan and 12 counties in Texas from 2005 to 2009.

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They used a statistical concept called hazard ratio, which estimates the chances of a particular health outcome occurring during the study time frame. Scores greater than 1 signaled an increased miscarriage risk each day following conception, and scores less than 1 meant a reduced risk.

Study authors observed miscarriage was associated with female age of 35 and above, for a hazard ratio of 1.96, which was about twice the miscarriage risk of younger women.

Male and female consumption of two caffeinated beverages daily was linked with a heightened hazard ratio—1.74 for females and 1.73 for males.

“Our findings also indicate that the male partner matters, too,” Dr. Buck Louis said in the release. “Male preconception consumption of caffeinated beverages was just as strongly associated with pregnancy loss as females’.”

The research also suggested a 55 percent reduction in risk for pregnancy loss among women who took a daily multivitamin during the preconception period. Study authors observed a hazard ratio of .45 for this variable during that time period. Women who continue to take the vitamins through early pregnancy also saw a hazard ratio of .21, equal to a risk reduction of 79 percent.

Previous research has suggested that vitamin B6 and folic acid can reduce miscarriage risk, the authors noted. Taking a folic acid supplement in the weeks leading up to and after conception also has been linked to a reduced risk of having a child with a neural tube defect.