Do Maternal Factors Modify the Associations Between Iron Supplementation and Low Birth Weight in Sub-Saharan Africa?

Iron supplementation is recommended to reduce low birth weight (LBW) but its impact in Africa is underexplored. This study examines factors that may modify the effects of maternal iron supplementation on LBW in sub-Saharan Africa. Health Survey data from 26 sub-Saharan countries, including 149,346 woman–infant pairs, were analyzed. LBW (< 2500 g) was the outcome, and iron supplementation (yes/no) and its duration (none, < 90 days, or ≥ 90 days) were exposures. A regression modeling framework was used to assess associations, adjusting for potential confounders and stratification by country income level. Family income, mother's education, maternal age, and partner's education were assessed as potential effect modifiers. The prevalence of LBW was 10.36%. Maternal iron supplementation adherence was 37.34%, but lower among poor and young women (31.43%). Not taking iron supplements during pregnancy increased the odds of LBW (aOR 1.19; 95%CI: 1.09, 1.30). Longer duration (more than 90 days) reduced the odds of LBW (aOR 0.84; 95%CI: 0.76, 0.93). These impacts were greater among poor women (aOR 0.74; 95%CI: 0.64, 0.84), women/partner with no education (aOR 0.79; 95%CI: 0.67, 0.92), and younger age (aOR 0.72; 95%CI: 0.54, 0.97). Taking iron supplements longer during pregnancy contributes to lowering LBW in sub-Saharan countries. Younger mothers from poor areas with no education, along with those whose partners lack education, appear more vulnerable and may benefit from access to supplements. Enhancing adherence and addressing these disparities are key to addressing LBW in these settings.