The Effect of Maternal Multiple Micronutrient Supplementation on Female Early Infant Mortality Is Fully Mediated by Increased Gestation Duration and Intrauterine Growth.

Abstract

BACKGROUND:

Maternal micronutrient supplementation in pregnancy (MMS) has been shown to improve birth weight among infants in low- and middle-income countries. Recent evidence suggests that the survival benefits of MMS are greater for female infants compared to male infants, but the mechanisms leading to differential effects remain unclear.

OBJECTIVE:

The objective of this study was to examine the potential mechanisms through which MMS acts on infant mortality among Tanzanian infants.

METHODS:

We used data collected from pregnant women and newborns in a randomized, double-blind, placebo-controlled trial of MMS conducted in Tanzania to examine mediators of the effect of MMS on 6-wk infant mortality (NCT00197548). Causal mediation analyses with the counterfactual approach were conducted to assess the contributions of MMS on survival via their effects on birth weight, gestational age, weight-for-gestational age, and the joint effect of gestational age and weight-for-gestational age. The weighting method allowed for interaction between gestational age and weight-for-gestational age.

RESULTS:

Among 7486 newborns, the effect of MMS on 6-wk survival was fully mediated (100%) through the joint effect of gestational age and weight-for-gestational age. MMS was also found to have a significant natural indirect effect through increased birth weight (P-value < 0.001) that explained 75% of the total effect on 6-wk mortality. When analyses were stratified by sex, changes in gestational age and weight-for-gestational age fully mediated the mortality effect among female infants (n = 3570), but these mediators only explained 34% of the effect among males (n = 3833).

CONCLUSIONS:

The potential sex-specific effects of MMS on mortality may be a result of differences in mechanisms related to birth outcomes. In the context of the Tanzanian trial, the observed effect of MMS on 6-wk mortality for female infants was entirely mediated by increased gestation duration and improved intrauterine growth, while these mechanisms did not appear to be major contributors among male infants.

• Authors: Mary K Quinn, Emily R Smith, Paige L Williams, Willy Urassa, Joy Shi, Gernard Msamanga, Wafaie W Fawzi, Christopher R Sudfeld
• Journal: The Journal of nutrition (J Nutr) Vol. 150 Issue 2 Pg. 356-363 (02 01 2020) ISSN: 1541-6100 [Electronic] United States
• PMID: 31605616 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)
• Copyright: Copyright © American Society for Nutrition 2019.

Chemical References

• Micronutrients

Topics

• Adult
• Dietary Supplements
• Female
• Fetal Development
• Humans
• Infant
• Infant Mortality
• Micronutrients (administration & dosage)
• Tanzania
• Young Adult