Vitamin D Supplementation During Pregnancy: Position Statement of the Groupe De Recherche Et D'information Sur Les Ostéoporoses (GRIO).

Background: Vitamin D plays critical roles in maternal and fetal skeletal health; its deficiency during pregnancy is common worldwide but the interest of its supplementation is not clearly established.Objective: This review aims to synthesize current evidence on vitamin D supplementation during pregnancy, with a focus on safety, efficacy, maternal and neonatal outcomes, and to revisit current French GRIO recommendations.Methods: A narrative review of mostly recent meta-analyses of clinical trials aimed to identify skeletal and extra-skeletal effects of supplementation, as well as dosage and safety considerations.Results: Vitamin D supplementation during pregnancy has been shown to improve neonatal bone mineralization and decrease the incidence of neonatal hypocalcemia and rickets. Evidence also suggests a protective role against preeclampsia and possibly gestational diabetes, although findings remain heterogeneous across populations. Recommended daily vitamin D intakes vary widely between international authorities, from 400 IU to 4,000 IU.Conclusion: In pregnant women, vitamin D supplementation may help reduce skeletal and extra skeletal risk, is associated with improved outcomes in some studies, with strongest evidence for skeletal outcomes and should be implemented as soon as possible during pregnancy. Further high-quality studies are however warranted to refine optimal dosing strategies and long-term outcomes.