Multivitamin Supplementation Is Associated with Greater Adequacy of Gestational Weight Gain among Pregnant Women in Tanzania

Abstract

Background: Gestational weight gain (GWG) is a modifiable risk factor associated with adverse birth outcomes. Studies have shown that the provision of multiple micronutrient supplements to pregnant women reduces the risk of low birth weight. However, the effect of multiple micronutrient supplements on GWG has been understudied.

Objectives: We examined the effect of daily supplementation of pregnant women with multivitamins on GWG in relation to the GWG recommendation by the Institute of Medicine (IOM).

Methods: Pregnant women with gestational age between 12 and 27 wk were randomly assigned to receive daily multivitamins or placebo until delivery. Weight was measured at enrollment and every follow-up visit. Percentage adequacy of GWG was calculated as actual GWG divided by the recommended GWG according to the IOM recommendation. Binary outcomes included severely inadequate (<70%), inadequate (<90%), and excessive GWG (≥125%). The analysis included 7573 women with singleton pregnancies. Multiple linear regression models were used to examine the association between multivitamin supplementation and percentage adequacy of GWG, and log-binomial models were used for binary outcomes.

Results: The mean percentage adequacy of GWG was 96.7% in the multivitamin arm and 94.4% in the placebo arm, with a mean difference of 2.3% (95% CI: 0.3%, 4.2%; P = 0.022). Compared with women in the placebo arm, those who received multivitamins had a lower risk of severely inadequate GWG (RR: 0.90; 95% CI: 0.83, 0.97; P = 0.008) and inadequate GWG (RR: 0.95; 95% CI: 0.91, 0.99; P = 0.018). No significant difference was found in excessive GWG.

Conclusions: Multivitamin supplementation increased GWG and reduced the risk of severely inadequate and inadequate GWG among pregnant women in Tanzania. Together with previously reported beneficial effects of the supplements on birth outcomes in low- and middle-income countries, our findings support scaling up the use of prenatal supplements that include multivitamins in addition to iron and folic acid.This trial was registered at clinicaltrials.gov as NCT00197548.

Keywords: Institute of Medicine; Tanzania; body mass index; gestational weight gain; prenatal multivitamin supplementation.