Role of Vitamin D in Prevention of Preeclampsia Recurrence in Pregnant Women with Previous History of Preeclampsia: A Randomized Controlled Trial

Vitamin D deficiency may contribute to abnormal placentation and endothelial dysfunction leading to preeclampsia (PE). Objectives: To compare the recurrence of preeclampsia in pregnant females having a previous history of PE receiving vitamin D supplementation versus placebo. Methods: This double-blind randomized controlled trial was done at the Department of Obstetrics and Gynecology, Nishtar Hospital, Multan, over six months from August 2025 to February 2026. A total of 146 pregnant ladies, 20-45 years old, with singleton pregnancy, gestational age ≥20 weeks, and previous preeclampsia were enrolled. Women with chronic hypertension, cardiac diseases, renal disease, and thyrotoxicosis were excluded. Participants were randomized to receive either oral vitamin D 4000 IU daily or a placebo. Follow-up continued until 36 weeks. Preeclampsia recurrence was defined as hypertension ≥140/90 mmHg with proteinuria ≥+1 on spot urine test. Data were analyzed through SPSS version 27.0, descriptive statistics were run, group comparisons were done through chi-square and independent sample t-test as required, and a p-value<0.050 was considered significant. Results: Mean age was 27.9 ± 4.6 years, and mean gestational age was 30.5 ± 2.8 weeks. Age and gestational age differed between the groups. Overall recurrence of preeclampsia was 21.9%. Recurrence was markedly less in the vitamin D compared to placebo (13.7% vs. 30.1%, relative risks 0.46, p=0.016) groups. Significant reductions were observed among women aged <30 years, gestational age 24-30 weeks, and non-obese participants. Conclusions: Vitamin D therapy decreased recurrence of preeclampsia in high-risk pregnant females, supporting its potential role as an effective preventive strategy in antenatal care.