<![CDATA[Preeclampsia is a hypertensive disorder of pregnancy that contributes substantially to maternal and perinatal morbidity and mortality. Vitamin D may influence placentation, immune regulation, endothelial function, angiogenesis, and the renin–angiotensin system; therefore, low vitamin D status has been associated with preeclampsia risk. This structured literature review covered publications from the last 10 years (2016–11 August 2026), prioritizing randomized controlled trials, systematic reviews/meta-analyses, umbrella reviews, and relevant clinical or public-health guidance. Several recent meta-analyses reported lower preeclampsia incidence with vitamin D supplementation, with effect estimates around RR 0.55–0.62 or OR 0.50–0.58. Nevertheless, the evidence is not fully consistent. The 2024 Cochrane update judged the evidence for vitamin D alone on preeclampsia to be very uncertain after studies with trustworthiness concerns were excluded. Heterogeneity in baseline 25-hydroxyvitamin D status, dose, timing, comparators, maternal risk profiles, and study quality remains substantial. Vitamin D has biological plausibility and a possible adjunctive preventive role, particularly among women with deficiency, but current evidence is insufficient to support universal vitamin D supplementation specifically for preeclampsia prevention. Well-powered multicenter trials with standardized baseline assessment, dosing regimens, safety monitoring, and adjudicated preeclampsia phenotypes are required.]]>
