Vitamin D deficiency in pregnancy is not associated with obstructed labor - A study among Pakistani women in Karachi

Background Vitamin D deficiency is widespread among pregnant Pakistanis in Norway. It may cause osteomalacia with destruction of maternal pelvis, and thus be a risk factor for cephalopelvic disproportion. This study was performed to determine whether vitamin D deficiency is common among pregnant Pakistanis in Pakistan, and to test the hypothesis that vitamin D deficiency in nulliparous pregnant women is associated with mechanical dystocia. Methods. The study was carried out at the Civil Hospital, in a poor area of Karachi, and had a case-referent design. Thirty-seven nulliparous parturients with Cesarean section due to mechanical dystocia served as cases, and 80 nulliparous parturients with uncomplicated vaginal delivery were their referents. All blood samples were drawn before parturition. Results. The mothers with obstructed labor were shorter (on average 150 vs. 155 cm, p=0.0001) and lighter (on average 58 vs. 60.5 kg, p=0.005) than their referents. Seventy-one percent (83/117) of all the participants had marginal or low vitamin D status defined as serum level of calcidiol (25-OH vitamin D-3) below 30 nmol/l. Vitamin D deficiency was, however, not more widespread among the mothers with obstructed labor (20/37 vs. 63/80). Furthermore, there were no significant differences in the serum levels of the carboxyterminal telopeptide of type I collagen, a sensitive biochemical marker of bone resorption, (7.2 vs. 6.6 mu g/l), and bone specific alkaline phosphate (18.1 vs. 22.0 U/l) a sensitive marker of bone formation. Conclusions. Vitamin D deficiency in pregnancy is common in Karachi, but is not associated with mechanical dystocia.