Abstract
Cumulative evidence supports a causal associationbetween tobaccouse inpregnancy and intrauterinegrowth restriction,1,2 and a plausible association between smoking and low levels of maternal folic acid.3 Given this evidence, we conducted a doubleblind, randomizedclinical trial to determine the efficacy of higher-dose folic acid in preventing a reduction in fetal body size among infants of women who smoked tobacco cigarettes during pregnancy