The study investigated the relationship between maternal serum 25-hydroxyvitamin D [25(OH)D] levels and the likelihood of vaginal delivery in 298 pregnant women from Turkey. The case group included 249 women who underwent emergency caesarean section, the control group women with vaginal delivery. Higher 25(OH)D levels were significantly associated with a reduced risk of caesarean section (β = −0.369, p = 0.001), with each increase of 1 ng/ml reducing the risk by 30.8% [Exp(β) = 0.692, 95% CI = 0.611–0.783]. High pre-pregnancy and delivery BMI, excessive gestational weight gain and chronic diseases increased the risk of caesarean section (p < 0.05). Delivery at a later gestational week was associated with a higher rate of vaginal delivery (p < 0.05). No significant associations were found with maternal age, number of pregnancies, previous vaginal delivery, contraceptive method, child's birth weight, number of NST tests or antenatal visits (p > 0.05).