A study including more than 80,000 Norwegian children found that folic acid supplementation early in pregnancy is associated with a 40% reduction in the risk of developing severe autism. However, there was no association found between maternal folic acid supplementation in the middle of pregnancy and the likelihood of a child developing autistic disorder.
Folic acid supplementation is best started one month prior to conception and continued through pregnancy and breast feeding. The usual dose is 0.6mg (600mcg) daily for pregnant women and then reduced to 0.5mg (500mcg) during breast feeding. Folic acid is found in most prenatal vitamin formulas but can be purchased separately if necessary. Be sure to check with your physician if you have any questions or concerns.