Methionine loading tests and folate, vitamin B-6, and vitamin B-12 analyses
were performed in 27 mothers of children with congenital heart defects. Me
dian fasting plasma homocysteine concentrations were significantly higher i
n the study group as compared with 56 control subjects (P =.0001). Maternal
hyperhomocysteinemia may be a risk factor for congenital heart defects.