This randomized, double-blind, placebo-controlled trial evaluated the effect of multimicronutrient supplementation (MMS) for undernourished pregnant women in Delhi, India, on the birth size of their offspring, the incidence of low-birth-weight (LBW) infants, and early neonatal morbidity. The intervention group received a multimicronutrient supplement (MMS) containing 29 vitamins and minerals once a day, from enrollment until delivery. The comparison group received a placebo for 52 days, with 85% compliance. All participants also received iron and folic acid (IFA) supplements. Infants in the micronutrient group were heavier by 98 g and measured 0.80 cm longer and 0.20 cm larger in midarm circumference compared with the placebo group. Incidence of low birth weight declined from 43.1% to 16.2% with multimicronutrient supplementation and that of early neonatal morbidity declined from 28.0% to 14.8%. Therefore, compared with IFA supplementation, MMS given to undernourished pregnant women may reduce the incidence of low birth weight and early neonatal morbidity.