Asian Journal of Food Research and Nutrition

Maternal vitamin D deficiency remains a common but under-addressed nutritional problem across high-, middle-, and low-income settings, with reported prevalence ranging from single digits to more than ninety per cent depending on region, skin pigmentation, latitude, and dietary pattern. Vitamin D acts as a secosteroid hormone with wide-ranging actions on placental implantation, immune tolerance, calcium homeostasis, and fetal organogenesis, and its deficiency during pregnancy has been linked with a broad spectrum of adverse maternal and offspring outcomes. This review synthesises evidence from observational cohorts, randomised controlled trials, and meta-analyses examining the association between maternal vitamin D status and outcomes including preeclampsia, gestational diabetes mellitus, preterm birth, postpartum depression, offspring skeletal development, respiratory and allergic disease, neurodevelopmental and psychiatric outcomes, and long-term metabolic programming consistent with the developmental origins of health and disease framework. The evidence shows a consistent pattern: observational studies report clear associations between low vitamin D status and adverse outcomes, while randomised trials of supplementation show more modest, outcome-specific benefit. This discordance is examined in detail. Building on this evidence, the review proposes a maternal health systems roadmap that integrates universal antenatal supplementation, targeted food fortification, risk-based screening, and structural incorporation of vitamin D interventions into existing antenatal care platforms, with particular attention to feasibility in low- and middle-income countries. The review concludes that a single global policy is unlikely to be optimal. Context-adapted, health-system-embedded strategies, supported by robust monitoring and governance, represent the most defensible route to reducing the maternal and intergenerational burden of vitamin D deficiency.