Folic acid supplements are recommended for women of childbearing age to prevent neural tube defects--such as spina bifida and anencephaly--in their children. However, results from some small studies have suggested that consumption of vitamins containing folic acid during pregnancy can lead to an increased chance of having a multiple pregnancy--with associated increased risk of complications and poorer health outcomes of infants.
Robert J. Berry from the Centers for Disease Control and Prevention, Atlanta, USA, and colleagues from China assessed the incidence of multiple births in around 240,000 Chinese women who used 400 microgram daily folic acid supplements as part of a community health campaign to prevent neural tube defects. The investigators report that women who used supplements before and during early pregnancy did not have an increased likelihood of multiple births compared with women who did not use folic acid supplements--the overall rate in both groups of women was around 0.6%.
Robert J Berry comments: "Our findings suggest that consumption of 400 micrograms of folic acid alone per day, before and during early pregnancy, does not increase a woman's likelihood of having a multiple birth, whether taken before the estimated date of ovulation, around the estimated time of fertilisation, or after conception."