Background: Maternal vitamin D deficiency is a widespread public health problem as the prevalence of inadequate and deficient vitamin D status in pregnant women ranges from 5 to 84% globally. Objective: To assess risk factors for vitamin D deficiency and investigate the relation between maternal vitamin D level, and development of gestational diabetes mellitus, gestational hypertension, intrauterine growth retardation, and preterm labor. Patients and methods: Our prospective observational study included 100 pregnant women divided into 2 equal groups: group A had insufficient vitamin d level and group B had sufficient vitamin D level in serum with no risk factors. Vitamin D levels were measured on the MiniVidas (Biomerieux, France). Results: The incidence of preterm labor was 22%. There was a statistically significant association between hypovitaminosis D and preterm labor. There was no significant association between hypovitaminosis D and gestational diabetes mellitus, gestational hypertension and intrauterine growth retardation. Conclusion: There was an association between hypovitaminosis D in pregnancy and preterm deliveries, No association between vitamin D deficiency and common pregnancy complications as gestational diabetes, gestational hypertension and intra uterine growth retardation.