Effects of vitamin A and β-carotene supplementation on birth size and length of gestation in rural Bangladesh: a cluster-randomized trial.

BACKGROUND Micronutrient deficiencies may be related to poor fetal growth and short gestation. Few studies have investigated the contribution of maternal vitamin A deficiency to these outcomes. OBJECTIVE In rural northwestern Bangladesh, we examined the effects of weekly antenatal vitamin A and β-carotene supplementation on birth weight, length, circumferential body measures, and length of gestation. DESIGN With the use of a cluster-randomized, placebo-controlled trial design, pregnant women were enrolled in the first trimester and began receiving their allocated supplements (vitamin A, β-carotene, or placebo) weekly until 3 mo postpartum. Birth anthropometric measures were made at home. RESULTS Of 13,709 newborns whose birth weight was measured within 72 h of birth, mean (±SD) weight was 2.44 ± 0.42 kg, the prevalence of low birth weight (LBW) was 54.4%, and that of small-for-gestational age (SGA) was 70.5%. Birth weight, length, and chest, head, and arm circumferences did not differ between supplementation and placebo groups nor did rates of LBW and SGA. Mean gestational age at birth was 38.3 ± 2.9 wk, and 25.6% of births occurred before 37 wk. Neither gestational age nor preterm birth rate differed with vitamin A or β-carotene supplementation. CONCLUSIONS In this rural South Asian population with a high burden of LBW and preterm birth but modest levels of maternal vitamin A deficiency, antenatal vitamin A or β-carotene supplementation did not benefit these birth outcomes. Other nutritional and nonnutritional interventions should be examined to reduce risks of these adverse outcomes in rural South Asia. This trial was registered at clinicaltrials.gov as NCT00198822.