Abstract:
Background
Prematurity and low birth weight are associated with high perinatal and infant mortality,
especially in developing countries. Maternal micronutrient deficiencies may
contribute to these adverse outcomes.
Methods
In a double-blind trial in Dar es Salaam, Tanzania, we randomly assigned 8468 pregnant
women (gestational age of fetus, 12 to 27 weeks) who were negative for human
immunodeficiency virus infection to receive daily multivitamins (including multiples
of the recommended dietary allowance) or placebo. All the women received prenatal
supplemental iron and folic acid. The primary outcomes were low birth weight
(<2500 g), prematurity, and fetal death.
Results
The incidence of low birth weight was 7.8% among the infants in the multivitamin
group and 9.4% among those in the placebo group (relative risk, 0.82; 95% confidence
interval [CI], 0.70 to 0.95; P = 0.01). The mean difference in birth weight between
the groups was modest (67 g, P<0.001). The rates of prematurity were 16.9% in the
multivitamin group and 16.7% in the placebo group (relative risk, 1.01; 95% CI, 0.91 to
1.11; P = 0.87), and the rates of fetal death were 4.3% and 5.0%, respectively (relative
risk, 0.87; 95% CI, 0.72 to 1.05; P = 0.15). Supplementation reduced both the risk of
a birth size that was small for gestational age (<10th percentile; 10.7% in the multivitamin
group vs. 13.6% in the placebo group; relative risk, 0.77; 95% CI, 0.68 to 0.87;
P<0.001) and the risk of maternal anemia (hemoglobin level, <11 g per deciliter; relative
risk, 0.88; 95% CI, 0.80 to 0.97; P = 0.01), although the difference in the mean
hemoglobin levels between the groups was small (0.2 g per deciliter, P<0.001).
Conclusions
Multivitamin supplementation reduced the incidence of low birth weight and smallfor-
gestational-age births but had no significant effects on prematurity or fetal death.
Multivitamins should be considered for all pregnant women in developing countries.
