Maternal vitamin D status, deficiency prevention strategies, and perinatal health outcomes

Adequate maternal nutrition is vital for fetal development and maternal health. Although vitamin D is a widely utilized prenatal supplement, its clinical efficacy in improving major pregnancy outcomes remains a topic of debate. This study reviewed the physiological roles of vitamin D, evaluated the clinical impact of maternal supplementation on perinatal indices, and provided practical clinical recommendations within the context of regional public health challenges. Although observational data have consistently associated low maternal 25-hydroxyvitamin D levels with adverse outcomes, interventional evidence from randomized controlled trials (RCTs) regarding the preventive effects of vitamin D supplementation on major obstetric complications, including preeclampsia, gestational diabetes mellitus, and preterm birth, remains limited, highly variable, and condition-specific. A high prevalence of vitamin D deficiency has been reported among women of childbearing age in South Korea, highlighting the importance of maternal vitamin D status from a public health perspective. For pregnant women with confirmed or suspected deficiency, a daily regimen of 1,000-2,000 IU may help achieve adequate maternal vitamin D status, taking into account dietary intake, food fortification, and prenatal vitamin use. However, the existing evidence does not support universal vitamin D supplementation solely for the prevention of major obstetric complications. Future research should shift toward precision medicine by conducting large-scale RCTs stratified by maternal body mass index, genetic polymorphisms, and behavioral and environmental factors, including smoking and sunlight exposure.