Linking Serum Vitamin D Deficiency and Menstrual Irregularities in North Karnataka: Insights from a Cross-sectional Study

BACKGROUND: Menstrual irregularities are common among young women and may be associated with Vitamin D deficiency, as it may play a role in reproductive and menstrual health. AIM: The aim is to evaluate and compare the serum Vitamin D levels in women with regular and irregular menstrual cycles in a tertiary care hospital in North Karnataka. MATERIALS AND METHODS: This comparative cross-sectional study was carried out in the Department of Obstetrics and Gynecology, Tertiary Care Teaching Hospital, from March 2025 to February 2026. A total of 150 women aged 18-25 years were enrolled, of which 75 were women with regular menstrual cycles and 75 women with irregular menstrual cycles. Detailed demographic and menstrual history was obtained using a structured pro forma. The serum level of 25-hydroxy Vitamin D (25[OH]D) was classified as deficient (<20 ng/mL), insufficient (20-30 ng/mL), and sufficient (≥30 ng/mL). RESULTS: The mean serum Vitamin D level was significantly lower in women with irregular menstrual cycles than in women with regular menstrual cycles (15.9 ± 6.4 vs. 26.8 ± 7.9 ng/mL, P < 0.001). The incidence of Vitamin D deficiency was found to be 72.0% in women with irregular cycles and 25.3% in women with regular cycles. Vitamin D deficiency was an independent risk factor for menstrual irregularity (adjusted odds ratio = 4.82; 95% confidence interval: 2.11-10.97; P < 0.001) using multivariate logistic regression analysis. CONCLUSION: In young women, low serum Vitamin D levels were significantly associated with menstrual irregularities. Evaluation of Vitamin D status could help in the early detection and treatment of women at risk of menstrual abnormalities.