Abstract Introduction: One of the most common causes of neonatal morbidity and mortality, particularly in sub-Saharan Africa, is pre-term delivery. Maternal vitamin D deficiency has been linked to various adverse pregnancy outcomes, such as preterm delivery, yet findings remain inconsistent and limited, especially in low and middle-income countries like Nigeria. Therefore, this study aimed to assess maternal vitamin D levels and their association with preterm delivery at Usmanu Danfodiyo University Teaching Hospital (UDUTH), Sokoto. Methods: A cross-sectional comparative study was conducted over five months among parturients at Usmanu Danfodiyo University Teaching Hospital (UDUTH), Sokoto. A total of 120 participants (60 per group) were recruited through systematic sampling and randomly allocated to two groups: those with preterm delivery (28 to <37 weeks) and those with term labour (≥37 weeks). Maternal serum vitamin D levels were measured using a solid-phase ELISA (Monobind Inc., USA). Data analysis was performed using SPSS. Chi-square tests were used to detect associations and identify predictors, respectively, at a 0.05 level of significance. Results: The mean serum vitamin D level in the preterm group was 26.67 ± 14.97, whereas in the term group, it was 49.55 ± 18.10. The prevalence of low serum vitamin D levels among parturients with preterm delivery was 76.7%, compared to 15% in those with term delivery. There was a statistically significant association between serum vitamin D levels and gestational age: parturients with preterm delivery had lower vitamin D levels than those with term delivery. (χ2 (1) = 43.502, p < 0.05). Conclusion: The present study demonstrated that serum vitamin D deficiency was more common among women with preterm delivery than those with term delivery. Therefore, measuring serum vitamin D during pregnancy may prove to be a useful tool in predicting the onset of preterm labour.