A mother’s nutrition during the first month of pregnancy may be critical in determining a child’s risk of developing Down syndrome (DS), according to a recent study. In particular, researchers found that an adequate intake of iron and folic acid can significantly lower the risk.

DS is a disorder that results from a chromosomal abnormality and is accompanied by mental retardation that is usually mild to moderate in severity. The risk of having a baby with DS increases with a mother’s age.

The study compared nutrient intakes during pregnancy of mothers of babies with DS with nutrient intakes of mothers with similar characteristics but no DS babies, mothers of babies with birth defects other than DS, and mothers of healthy babies. Data regarding the use of vitamins, minerals and medications during pregnancy was collected via questionnaires, medical records and home nurse visits.

The researchers found that those who took folic acid and iron during the first month of pregnancy had a significantly lower chance of having a baby with DS than did women who hadn’t taken these nutrients. The nutrients were not protective, however, if supplementation was started after the first month. Most women (70%) supplementing with folic acid took 6 mg per day, which is much more than the current recommendation by the March of Dimes of 0.4 mg to prevent neural tube defects. Importantly, small doses of folic acid (less than 1 mg per day) did not appear to protect against DS.

Nutrition 2005;21:698–704