Effect of preconception multiple micronutrients vs. iron–folic acid supplementation on maternal and birth outcomes among women from developing countries: a systematic review and meta-analysis

Maternal malnutrition affects the somatic growth of the fetus and subsequent adverse events during infancy and childhood period. Though trials have been conducted on multiple micronutrient (MMN) supplements initiated during the preconception period, there is no collated evidence on this.We performed a systematic review of published trials with the application of Grading of Recommendations Assessment, Development, and Evaluation (GRADE). The searches were conducted until 30 September 2023. Meta-analysis was performed using Review Manager 5 software. The primary objective was to compare the effect of preconception MMN vs. iron–folic acid (IFA) supplementation on newborn anthropometric parameters at birth.Of the 11,832 total citations retrieved, 12 studies with data from 11,391 participants [Intervention = 5,767; Control = 5,624] were included. For the primary outcome, there was no significant difference in the birth weight [MD, 35.61 (95% CI, −7.83 to 79.06), p = 0.11], birth length [MD, 0.19 (95% CI, −0.03 to 0.42), p = 0.09], and head circumference [MD, −0.25 (95% CI, −0.64 to −0.14), p = 0.22] between the MMN and control groups. For all the secondary outcomes [except for small for gestational age (SGA) and low birth weight (LBW)], the difference between the MMN and control groups was not significant. The GRADE evidence generated for all the outcomes varied from “very low to moderate certainty.”A “very low certainty” of evidence suggests that MMN supplementation may not be better than routine IFA supplementation in improving newborn anthropometric parameters (weight, length, and head circumference). The adverse events resulting from the supplementation were not significant. We need better quality uniformly designed RCTs before any firm recommendation can be made.Systematic review registration: identifier (CRD42019144878: https://www.crd.york.ac.uk/prospero/#searchadvanced).