Nutrition and reproductive potential of women in low- and middle-income countries: a systematic review and meta-analysis

Introduction: Nutrition plays a critical role in key physiological processes related to reproduction. However, there is limited understanding of the impact of nutritional factors and interventions on the reproductive outcomes of women in low- and middle-income countries (LMICs). Methods: This systematic review and meta-analysis aimed to synthesise evidence regarding the impact of nutritional factors and interventions on the reproductive outcomes of women in LMICs. Outcomes of interest included fertility and fecundity, menarche and menstrual disorders, miscarriage, stillbirth and live birth. Randomised controlled trials (RCTs) and non-randomised intervention studies with nutritional interventions, and observational cohort studies with nutritional factors, were included. Study selection, data extraction and risk of bias assessment were independently completed by two reviewers. A narrative synthesis of included studies was conducted, and meta-analyses were conducted when feasible. Results: Systematic search identified 180 studies, including 47 intervention studies and 133 observational cohort studies. From RCTs, there was no clear evidence for an effect of prenatal multiple micronutrient supplementation on the risk of miscarriage (8 RCTs; risk ratio (RR): 0.87; 95% CI 0.75, 1.02; moderate certainty of evidence) or stillbirth (15 RCTs; RR: 0.86; 95% CI 0.73, 1.02; low certainty of evidence). From observational cohort studies, preconceptional obesity was associated with a greater risk of miscarriage (12 studies; RR: 1.27; 95% CI 1.10, 1.47; very low certainty of evidence) and stillbirth (4 studies; RR: 1.66; 95% CI 1.28, 2.14; very low certainty of evidence). Any anaemia during pregnancy was associated with a greater risk of stillbirth (10 studies; RR: 1.26; 95% CI 1.01, 1.58; very low certainty of evidence). Conclusion: This review highlights the importance of ensuring preconceptional nutrition and preventing anaemia during pregnancy for favourable reproductive outcomes. This review calls for randomised controlled trials to evaluate the effectiveness of preconceptional and prenatal interventions on these outcomes.