LONDON (Reuters Health) – While many studies have shown that maternal folic acid use reduces the risk of fetal neural tube defects, the vitamin's effects on other pregnancy outcomes is unclear. A report published in the September 8th issue of The Lancet indicates that folic acid use does not increase the risk of miscarriage.
Dr. Robert J. Berry, from the US Centers for Disease Control and Prevention in Atlanta, and colleagues determined the miscarriage rate of 23,806 first-time pregnant Chinese women. Nearly 22,000 of them had taken 400-µg folic acid pills at some point before becoming pregnant or during early pregnancy, without use of other supplements, as part of a public health campaign in which their folic acid use was documented.
The overall miscarriage rate was 9.1%, the authors state. The 9.0% rate among women who took folic acid was not significantly different from the 9.3% rate among women who did not take the vitamin. The mean gestational age at pregnancy diagnosis and at miscarriage were similar in the two groups.
"Published reports on the relation between folic acid supplementation during pregnancy and risk for miscarriage have been inconsistent," the authors state. "Several studies have reported that defects in folic acid and homocysteine metabolism, folic acid antagonists, and folic acid deficiency are associated with an increased risk for pregnancy loss." Others, however, have suggested that folic acid use increases the miscarriage risk.
But the investigators note that in the current study, the miscarriage rate was "actually lower than that reported for women in the general population who did not use folic acid in other studies of pregnancy."