Folic acid is an essential vitamin, meaning that people must consume folic acid in the diet, as the body is unable to manufacture it on its own. Strong evidence shows that women who take supplemental folic acid at the time of conception are less likely to give birth to children with neural tube defects such as spina bifida. If folic acid plays a crucial role in early brain development, it may also impact the risk for autism.

Recent epidemiological research¹,² suggests that supplemental folic acid at the time of conception reduces the risk of autism in children, but studies to date have only examined populations in wealthy nations, where nutritional deficiency of folic acid is rare, as foods are routinely supplemented with it. It is therefore important to study the impact of folic acid supplementation at the time of conception in populations known to experience dietary deficiency of the vitamin.

Joseph Cubells and his colleagues at Emory University in Atlanta plan to evaluate the frequency of autism spectrum disorders in children born to women who participated in a landmark study of folic acid supplements at the time of conception, conducted in China in the 1990s³.

The women who participated either did or did not take folic acid supplements from before conception through the first trimester, and careful records were kept of each woman’s supplement intake. Some women lived in a part of China where, at the time, the typical diet was low in folic acid. Children born to women who took folic acid supplements were much less likely to have neural tube defects than children whose mothers did not.

Cubells and his colleagues aim to determine whether there is a different frequency of autism in the children (now in late adolescence) born to women who took folic acid supplements compared with those who did not. The study will provide clear information on the relationship between prenatal folic acid supplement use and the risk of autism in children, without the confounding factors found in countries where foods are routinely supplemented with folic acid.