Vitamins and Perinatal Outcomes Among HIV-Negative Women in Tanzania

The mother’s micronutrient status is a key determinant of fetal growth and survival. While iron and folate supplements now are provided to pregnant women in many developing countries, the dietary intake of other micronutrients often is inadequate. Multivitamin supplements have significantly lowered rates of fetal death, preterm birth, and low birth weight in HIV-positive Tanzanian women. The present, similarly designed trial was done to learn whether supplements are equally effective in HIV-negative women. The double-blind trial enrolled 8468 women at 12–27 weeks’ gestational age, all of whom received supplemental iron and folic acid prenatally. Participants received either a multivitamin supplement or placebo daily up to 6 weeks after delivery. The supplement included 20 mg of vitamin B1, 20 mg of vitamin B2, 25 mg of vitamin B6, 100 mg of niacin, 50 μg of vitamin B12, 500 mg of vitamin C, 30 mg of vitamin E, and 0.8 mg of folic acid. These doses were, on average, at least twice the recommended dietary allowance (RDA) and, in several instances, 6–10 times the RDA. Vitamin A and zinc were omitted. A total of 8137 women gave birth to a live infant and were eligible for analyses of birth weight and prematurity. Women in the supplement and placebo groups had similar baseline characteristics. The interval from randomization to 6 weeks postpartum averaged 5.6 months. Compliance during this interval averaged 80% and did not differ significantly between the two study groups. Low birth weight (less than 2500 g) was significantly less common in the multivitamin group than in placebo recipients; the relative risk (RR) was 0.82, with a 95% confidence interval (CI) of 0.70–0.95. Mean birth weight was modestly but significantly higher in the multivitamin group. Supplementation had no significant effects on the risk of either preterm birth (before 37 weeks’ gestation) or fetal death. The risk of a small-for-gestational-age infant was reduced 23% in the multivitamin group. The RR of cesarean delivery in the multivitamin group compared to the placebo group was 1.15 (95% CI, 0.99–1.33). Supplementation did not significantly influence the risk of maternal death. Maternal anemia was less frequent in women given supplements, and they had significantly higher hemoglobin levels. The low cost of vitamin supplements and their positive effects on the risk of low birth weight and a small-for-gestational-age infant recommend their use by all pregnant women. Prenatal vitamin supplementation could prove to be a very cost-effective means of improving birth outcomes in developing countries.