Vitamins and Perinatal Outcomes among HIV-Negative Women in Tanzania

Randomized, placebo-controlled trial among HIV-negative pregnant women attending antenatal clinics in Dar es Salaam, Tanzania. Women were enrolled at 12 to 27 weeks gestation; 4,214 women were randomized to the multivitamin arm in a 1:1 allocation design.

Daily oral prenatal multivitamin supplementation, taken once daily from enrollment until 6 weeks after delivery, in addition to standard prenatal iron (60 mg elemental iron daily) and folic acid (0.25 mg daily). The multivitamin contained vitamin B1 20 mg, vitamin B2 20 mg, vitamin B6 25 mg, niacin 100 mg, vitamin B12 50 μg, vitamin C 500 mg, vitamin E 30 mg, and folic acid 0.8 mg; vitamin A and zinc were not included.

Prenatal multivitamin supplementation improved fetal growth outcomes but did not meaningfully reduce prematurity or fetal death. Mean birth weight was 3148 g versus 3083 g, a 67 g increase (P<0.001), and low birth weight <2500 g was reduced from 9.4% to 7.8% (RR 0.82, 0.70 to 0.95; P=0.01). Small-for-gestational-age births were also lower at 10.7% versus 13.6% (RR 0.77, 0.68 to 0.87; P<0.001). Preterm birth <37 weeks was unchanged (16.9% vs 16.7%; RR 1.01, 0.91 to 1.11; P=0.87) and fetal death was not significantly different (4.3% vs 5.0%; RR 0.87, 0.72 to 1.05; P=0.15). Maternal anemia improved modestly (RR 0.88, 0.80 to 0.97; P=0.01), with hemoglobin increasing by 0.2 g/dL (P<0.001).

The multivitamin was added on top of routine iron and folic acid, so the specific contribution of the multivitamin components is not fully isolated. Dietary intake and physical activity were not reported by arm, and baseline BMI was missing for 12.3% of participants overall. Follow-up was limited to delivery and 6 weeks postpartum, and generalizability is most direct for HIV-negative pregnant women attending urban antenatal clinics in Tanzania.