Impacts of vitamin supplementation for pregnant and lactating women on maternal and infant nutritional status in low- and middle-income countries: protocol for a systematic review and meta-analysis (Preprint)

Abstract

Background: Two billion people in low- and middle-income countries (LMICs) are deficient in key nutrients. Nutritional deficiencies worsen during pregnancy, causing adverse outcomes for the mother and the fetus, with consequences after pregnancy. These effects may be mitigated by providing micronutrient supplementation to women during pregnancy and lactation. However, the impact of micronutrient supplementation during pregnancy on maternal and infant nutritional status is unclear in the context of LMICs. The purpose of this systematic review and meta-analysis is to determine the effects of single, double, or multiple micronutrient supplements during pregnancy or lactation for women on maternal and infant nutritional status in LMICs. Methods: Randomized controlled trials of single or combinations of micronutrients assessing effects on maternal and infant nutritional status will be included. MEDLINE (through PubMed), EMBASE, CENTRAL (through Cochrane Library), and the WHO library database will be used to identify relevant published studies. Cochrane Risk of Bias Tool will be used to assess the risk of bias in included studies. The selection of studies, data extraction, and risk of bias will be done independently by two reviewers. A narrative summary will be provided of all the included studies. Meta-analyses will be performed whenever possible, and the heterogeneity of effects will be evaluated using I2, subgroup analyses, and meta-regression. The certainty of the evidence for each outcome will be assessed using the GRADE approach (Grading of Recommendation, Assessment, Development, and Evaluation). Discussion: This review will provide evidence on which to base policy and programming for women in LMICs to supplement micronutrients in pregnancy and lactation. The review will also identify any gaps in the existing evidence. Systematic review registration: PROSPERO ID: CRD42022308715