Although taking folic acid supplements before and during early pregnancy reduces a women's risk of having a baby with a neural tube defect (NTD), the effects of such supplements on other pregnancy outcomes remain unclear. In this week's issue of The Lancet Jacqueline Gindler and colleagues at the Centres for Disease Control (CDC) in Atlanta and at the Beijing University's Health Science Centre, have assessed whether the use of these supplements affects the occurrence of miscarriage. They examined the risk of miscarriage in Chinese women who had registered in a folic acid campaign to prevent NTDs. Participants were women in China who had taken part in a recent folic acid campaign to prevent NTDs and who had registered in this campaign before they became pregnant for the first time. Researchers examined the risk for miscarriage among women who had confirmed pregnancies and who had or had not taken pills containing only 400 µg of folic acid before and during early pregnancy. The overall rate of miscarriage was 9.1 per cent. The rates of miscarriage among women who had and had not taken folic acid pills before and during the first trimester were 9.0 per cent and 9.3 per cent, respectively. The distributions of gestational age at pregnancy diagnosis and at miscarriage were similar for both groups of women. In this population-based study of a group of women whose use of folic acid supplements while pregnant had been previously documented and who had been pregnant for the first time, scientists found no evidence that daily consumption of 400 µg of folic acid before and during early pregnancy influenced their risk for miscarriage.