Objective: To assess the association between Gestational Vitamin D (VD) deficiency and preterm birth (PTB).
Patients and Methods: This prospective observational nested case control study was conducted at Ain Shams University Maternity Hospital and Dar Ismael Maternity Hospital and sequentially recruited women with singleton pregnancy at 20-28 weeks. Blood samples were collected from all eligible participants and kept frozen until further measurement of maternal VD levels. All enrolled women were followed up till delivery. Cases (PTB) group included woman who delivered before completing 37 weeks of gestation while controls, term birth (TB) group included matched group of those who delivered at or after 37 weeks. The primary study outcome measure was the correlation between VD status and PTB.
Results: The final analysis of this study included 40 cases in the PTB group and 40 controls in the TB group. VD deficiency was more prevalent in PTB group (87.5% versus 22.5% in the TB group, p<0.001). PTB group had a statistically significant lower VD levels (13.34 ± 7.71 ng/ml versus 32.91 ± 18.98 ng/ml in the TB group, p<0.001) with a moderate positive linear correlation between gestational age at delivery and VD level (Pearson correlation=0.571, p<0.001). Among the studied maternal outcomes, delivery by cesarean section was more prevalent in PTB group (62.5% versus 30.0% in the TB group, p=0.004).
Conclusion: Gestational VD deficiency was associated with increased risk of PTB and delivery by cesarean section