Background: Adverse maternal and neonatal outcomes as preterm delivery, preeclampsia, small for gestational age (SGA) and gestational diabetes mellitus have all been accused to be associated with low levels of maternal vitamin D during conception. Objective: to evaluate the relation between maternal and fetal outcomes and levels of maternal vitamin D during pregnancy Patients and methods: In total, 284 third-trimester pregnant women were included in this cohort study at Zagazig University Hospitals' Obstetric and Gynecologic Clinic. They were questioned about their pregnancy and the variables related to their vitamin D levels. Vitamin D level was measured in all participants. The participants were followed till delivery with reporting all adverse maternal, fetal, and neonatal outcomes. Results: When comparing the association between vitamin D concentration and sun exposure, residence, dressing style, dairy product consumption, occupation, and use of multivitamins women who wore clothing uncovered and who worked outside and were exposed to the sun had significantly higher vitamin D levels. Preeclampsia and hypertension incidences were higher in females with versus without vitamin D deficiency with statistically significant values [OR (CI) 5.4 (1.4-20.2) for preeclampsia and 7.3 (1.5-34.5) hypertension]. Conclusion: high prevalence of vitamin D deficiency was reported in late pregnancy, which was linked to factors as sun exposure, employment, usage of multivitamins, and dress code.