Background: Prenatal supplementation with micronutrients may increase birth weight and thus improve infant health and survival in settings where infants and children are at risk of micronutrient deficiencies. Objective: To assess whether vitamin A and/or zinc supplementation given during pregnancy can improve birth weight, birth length, neonatal morbidity, or infant mortality. Methods: A double-blind, randomized controlled trial supplementing women (n = 2173) in Central Java, Indonesia throughout pregnancy with vitamin A, zinc, combined vitamin A+zinc, or placebo. Results: Out of 2173 supplemented pregnant women, 1956 neonates could be evaluated. Overall, zinc supplementation improved birth length compared to placebo or combined vitamin A+zinc (48.8 vs. 48.5 cm, p = 0.04); vitamin A supplementation improved birth length compared to placebo or combined vitamin A+zinc (48.7 vs. 48.2 cm, p = 0.04). These effects remained after adjusting for maternal height, pre-pregnancy weight, and parity. There was no effect of supplementation on birth weight, the proportion of low birth weight, neonatal morbidity, or mortality. Conclusions: Prenatal zinc or vitamin A supplementation demonstrates a small but significant effect on birth length, but supplementation with zinc, vitamin A or a combination of zinc and vitamin A, have no effect on birth weight, neonatal morbidity, or mortality.