Vitamin D Therapy to Prevent Recurrent Preeclampsia in High-Risk Pregnancies

The goal of this clinical trial is to determine whether vitamin D supplementation can reduce the recurrence of preeclampsia in pregnant women with a previous history of preeclampsia. The main questions the study aims to answer are: \- Does daily vitamin D supplementation reduce the recurrence of preeclampsia compared with a placebo? Researchers will randomly assign 146 eligible pregnant women to receive either vitamin D supplements or a placebo. The two groups will be compared to determine whether vitamin D lowers the risk of recurrent preeclampsia. Participants will: * Be randomly assigned to receive either 4000 IU oral vitamin D once daily or a matching placebo. * Take the assigned study medication daily until 36 weeks of gestation. * Attend follow-up visits every 2 weeks for blood pressure measurement and clinical assessment. * Have serum vitamin D levels measured every 4 weeks to monitor for vitamin D toxicity. * Undergo urine testing for protein if blood pressure is elevated to assess for preeclampsia. The results of this study will help determine whether vitamin D supplementation is an effective and safe strategy for preventing recurrent preeclampsia in women at high risk.

Inclusion Criteria: * Pregnant women * Singleton pregnancy (on USG) * Gestational age ≥ 24-weeks (on LMP method) and * Past medical history of pre-eclampsia (on medical record) Exclusion Criteria: * Pre-existing chronic hypertension * Cardiac diseases (congenital or acquired) * Renal disease * Thyrotoxicosis (on history and medical record) and * Intra-uterine death of the fetus.