Vitamin D Deficiency Among Pregnant Women in Sub-Saharan Africa: A Systematic Review and Meta-Analysis

Vitamin D deficiency (VDD) during pregnancy is linked to adverse maternal and fetal outcomes. Deficiency may result from low cutaneous synthesis, poor dietary intake, or metabolic disruptions. In Sub-Saharan Africa (SSA), diverse climates, diets, and health systems may influence VDD prevalence, yet comprehensive data remains limited.

To estimate the pooled proportion of VDD among pregnant women in SSA.

A systematic review and meta-analysis were conducted on studies reporting VDD among pregnant women in SSA. Databases searched included PubMed, Scopus, Science Direct, HINARI, Google, and Google Scholar without restrictions on language or study period. Study quality was assessed with the Newcastle-Ottawa Scale. Heterogeneity was examined using Cochrane's Q and I² statistics. Publication bias was evaluated using Egger's test at a 5% significance level. A random-effects model was used to estimated the pooled proportion.

Thirty observational studies with 6853 pregnant women were included. Reported proportion ranged from 99.2% in Sudan to 1.6% in Zimbabwe. The pooled proportion of VDD was 34.8% (95% CI: 20.75, 48.76) with significant heterogeneity (I² = 99.83%, p < 0.001). Subgroup analysis showed the highest proportion in East Africa at 45.65% (95% CI: 17.68-73.63) and the lowest in Southern Africa at 13.83% (95% CI: 2.99-24.67). Most studies were high-quality, facility-based, and predominantly single-center.

VDD is common among pregnant women in SSA, particularly in East Africa, and may worsen maternal and neonatal health outcomes. Public health strategies, such as nutrition education and supplementation programs alongside food fortification policies are needed to reduce vitamin D deficiency.