May 22, 2009

Study links vitamins with lowered rate of miscarriage

Featured Image

Katherine Hartmann, M.D., Ph.D.

Study links vitamins with lowered rate of miscarriage

Many women who are trying to conceive take prenatal vitamins, and all women of childbearing age are advised to take vitamins to protect against birth defects. But a new study points to the potential power of vitamins to prevent miscarriage as well.

The research, published online this month in the American Journal of Epidemiology, comes from the population-based Right from the Start project headed by Katherine Hartmann, M.D., Ph.D., deputy director of the Vanderbilt Institute for Medicine and Public Health.

Hartmann is senior author of the study, entitled “Self-Reported Vitamin Supplementation in Early Pregnancy and the Risk of Miscarriage.” The first and subsequent authors are at the University of North Carolina at Chapel Hill, where Hartmann was prior to joining Vanderbilt two years ago, and where much of the research was completed.

Nearly 4,800 women were enrolled either before they became pregnant or within the first two months of pregnancy. Early ultrasounds confirmed pregnancies, and miscarriages occurred in 524 of the women.

A survey showed that 95 percent of the women, who came from many backgrounds, took prenatal vitamins or multivitamins. Those who did not take either had roughly twice the risk of miscarriage.

“While this is a large study, it is observational and so it has its limitations in drawing conclusions about cause and effect,” Hartmann said. “But there are many studies that indicate folate protects against birth defects, like neural tube defects and cleft lip/palate. There should be no hesitation to use our observed 50 percent reduction in the risk for miscarriage to bolster the use of pre-conception prenatal vitamins.”

The majority of women in this study were planning to conceive, while in the United States, about half of all pregnancies are unplanned.

“That makes our population different, but it doesn’t diminish the importance of this closer look at the effects of vitamins on the rate of miscarriage,” Hartmann said.

Hartmann said the question is made more interesting because the generally accepted theory is that 60 percent of early miscarriage is because of genetics.

“So much has changed in the last 30 to 50 years. More study is needed to find out if losses are more common now and if the overall mix of causes has shifted. Today’s nutrition might be worse for early pregnancy; more women have type 2 diabetes, we’re exposed to more environmental threats and it may be that advancing maternal age changes needs,” she said. “We are just working with old data and need new data.”