Effects of vitamin D in pregnancy on maternal and offspring health-related outcomes: An umbrella review of systematic review and meta-analyses

1. Background: The Importance of Vitamin D During Pregnancy Vitamin D is an essential fat-soluble vitamin that plays a critical role not only in calcium and phosphorus metabolism and bone development, but also in immune regulation, metabolic function, and fetal growth and development. Due to increased physiological demands during pregnancy, combined with insufficient sunlight exposure and inadequate dietary intake, vitamin D deficiency has become a common global health concern among pregnant women. Whether vitamin D deficiency adversely affects maternal and neonatal health, and whether vitamin D supplementation can improve these outcomes, remains an important issue in clinical medicine and public health. 2. Research Method: An Umbrella Review of Existing Evidence This study employed an umbrella review approach to comprehensively synthesize findings from published systematic reviews and meta-analyses examining the effects of maternal vitamin D status and vitamin D supplementation during pregnancy on maternal and offspring health outcomes. A systematic search was conducted in PubMed, Embase, and the Cochrane Library. Sixteen eligible systematic reviews and meta-analyses published up to October 2023 were included, representing data from more than 250,000 pregnant women. 3. Association Between Vitamin D Deficiency and Adverse Maternal and Neonatal Health Outcomes The findings indicate that vitamin D deficiency during pregnancy is significantly associated with several adverse maternal and neonatal health outcomes. Pregnant women with vitamin D deficiency are at increased risk of preterm birth, gestational diabetes mellitus, recurrent miscarriage, and bacterial vaginosis. Their infants are more likely to experience low birth weight, small-for-gestational-age (SGA) status, and other unfavorable birth outcomes. Furthermore, low maternal vitamin D levels may be associated with an increased risk of long-term neurodevelopmental disorders in offspring, including attention-deficit/hyperactivity disorder (ADHD) and autism spectrum disorder (ASD). 4. Benefits of Vitamin D Supplementation for Maternal and Neonatal Health The study found that appropriate vitamin D supplementation during pregnancy can increase maternal serum vitamin D concentrations and reduce the risk of pre-eclampsia, miscarriage, and vitamin D deficiency. For fetuses and newborns, vitamin D supplementation was associated with increased birth length, reduced fetal or neonatal mortality, and improved neonatal vitamin D status. 5. Additional Benefits for Women with Gestational Diabetes Mellitus The benefits of vitamin D supplementation appear to be particularly pronounced among women with gestational diabetes mellitus (GDM). Supplementation was associated with improved glycemic control and insulin sensitivity, as well as reduced risks of polyhydramnios, fetal distress, macrosomia, neonatal hyperbilirubinemia, and neonatal hospitalization. 6. Conclusions and Clinical Implications Overall, this study demonstrates that maternal vitamin D status is closely linked to both maternal and neonatal health. Maintaining adequate vitamin D levels during pregnancy may help reduce pregnancy-related complications and improve fetal growth, development, and long-term child health outcomes. The findings support routine monitoring of vitamin D levels, particularly among women at high risk of deficiency, and suggest that vitamin D supplementation during pregnancy should be considered. Current evidence indicates that supplementation with more than 400 IU/day of vitamin D may help prevent certain adverse maternal and neonatal outcomes. 7. Research Contributions and Future Perspectives The findings of this study provide valuable evidence for clinical practice, prenatal nutritional guidance, and public health policy development. By highlighting the importance of maintaining adequate vitamin D status during pregnancy, this research contributes to strategies aimed at improving the health and well-being of both mothers and their children.   (Provided by: Clinical Medical Research Center research team, Chia-Yi Christian Hospital)