ASSOCIATION BETWEEN MATERNAL VITAMIN D STATUS AND FAILED INDUCTION OF LABOR AT TERM: A PROSPECTIVE COHORT STUDY

Abstract

Background: Maternal vitamin D deficiency is common in pregnancy and may influence cervical ripening and labor progression. This study assessed the association between maternal vitamin D status and failed induction of labor at term.

Methods: This prospective cohort study included 250 women with term singleton pregnancies undergoing planned induction at POF Hospital, Wah Cantt, Pakistan, from February to December 2025. Serum 25-hydroxyvitamin D [25(OH)D] was measured before induction and categorized as deficient (<20 ng/mL), insufficient (20–29 ng/mL), or sufficient (≥30 ng/mL). Participants were followed until delivery. Failed induction was defined as failure to achieve active labor or progressive cervical dilatation despite appropriate cervical ripening and adequate uterotonic augmentation, resulting in cesarean delivery. Multivariable logistic regression assessed the independent association between vitamin D status and failed induction.

Results: Vitamin D deficiency was present in 102 (40.8%) women, insufficiency in 88 (35.2%), and sufficiency in 60 (24.0%). Overall, 65 (26.0%) women experienced failed induction. Failure rates were 39.2%, 21.6%, and 10.0% among deficient, insufficient, and sufficient groups, respectively. Mean 25(OH)D levels were lower in women with failed induction than in those with successful induction (17.2 ± 7.5 vs. 23.4 ± 8.3 ng/mL; p<0.001). After adjustment for relevant maternal and obstetric factors, vitamin D deficiency remained independently associated with failed induction (adjusted OR 4.21, 95% CI 1.61–11.02; p=0.003). A higher baseline Bishop score was independently associated with lower odds of failed induction (adjusted OR 0.69, 95% CI 0.57–0.84; p<0.001).

Conclusion: Maternal vitamin D deficiency was common and independently associated with increased odds of failed induction of labor at term. Further multicenter and interventional studies are warranted to determine whether optimizing vitamin D status can improve induction outcomes.