Effects of alternative maternal micronutrient supplements on low birth weight in rural Nepal: double blind randomised community trial

Abstract

Objective: To assess the impact on birth size and risk of low birth weight of alternative combinations of micronutrients given to pregnant women. Design: Double blind cluster randomised controlled trial. Setting: Rural community in south eastern Nepal. Participants: 4926 pregnant women and 4130 live born infants. Interventions: 426 communities were randomised to five regimens in which pregnant women received daily supplements of folic acid, folic acid-iron, folic acid-iron-zinc, or multiple micronutrients all given with vitamin A, or vitamin A alone (control). Main outcome measures: Birth weight, length, and head and chest circumference assessed within 72 hours of birth. Low birth weight was defined <2500 g. Results: Supplementation with maternal folic acid alone had no effect on birth size. Folic acid-iron increased mean birth weight by 37 g (95% confidence interval −16 g to 90 g) and reduced the percentage of low birthweight babies (<2500 g) from 43% to 34% (16%; relative risk=0.84, 0.72 to 0.99). Folic acid-iron-zinc had no effect on birth size compared with controls. Multiple micronutrient supplementation increased birth weight by 64 g (12 g to 115 g) and reduced the percentage of low birthweight babies by 14% (0.86, 0.74 to 0.99). None of the supplement combinations reduced the incidence of preterm births. Folic acid-iron and multiple micronutrients increased head and chest circumference of babies, but not length. Conclusions: Antenatal folic acid-iron supplements modestly reduce the risk of low birth weight. Multiple micronutrients confer no additional benefit over folic acid-iron in reducing this risk. What is already known on this topic: Deficiencies in micronutrients are common in women in developing countries and have been associated with low birth weight and preterm delivery What this study adds: In rural Nepal maternal supplementation with folic acid-iron reduced the incidence of low birth weight by 16% A multiple micronutrient supplement of 14 micronutrients, including folic acid, iron, and zinc, reduced low birth weight by 14%, thus conferring no advantage over folic acid-iron