Preterm birth (PTB) is a major adverse outcome in developing countries, including India, with serious adverse consequences. Although the pathophysiology is not fully understood, maternal biomarkers influencing placental function may contribute to premature rupture of membranes and PTB. Vitamin D₃ supplementation during pregnancy may lower the risk of PTB, particularly in populations with a high prevalence of vitamin D deficiency (~90% in India). However, available biomarkers for PTB prediction are non-confirmatory, costly and not part of routine care. The aim of the study is to evaluate whether 2000 IU/day vitamin D₃ supplementation during pregnancy reduces PTB compared with 500 IU/day (standard care).

Singleton pregnant women ≤18 weeks gestation with deficiency of 25-hydroxyvitamin D (

The study has been funded by the Department of Biotechnology, India (Grant Ref: BT/PR41941/MED/97/548/2021). Ethical clearance has been obtained from Institutional Ethics Committee (Ref No. IEC/344/2021), St. John’s Medical College & Research Institute and Ethics Committee of Bangalore Medical College & Research Institute (BMCRI/EC/25/2024). Study data will be disseminated through peer-reviewed publications and conference presentations.

Trial has been prospectively registered with Clinical Trials Registry - India (CTRI/2021/10/037658).