Ultrasound evaluation of placental volume and placental vascular indices in women developing hypertensive disorders in pregnancy compared to controls: a systematic review and meta-analysis

Abstract Aims: To assess whether first-trimester placental volume (PV) and vascular indices differ between pregnancies that subsequently develop preeclampsia (PE) or gestational hypertension (GH) and normotensive controls. Methods and results: Following PRISMA guidelines, a systematic review and meta-analysis were carried out across PubMed, Embase, and Web of Science, from inception until March 2025. Cross-sectional, cohort, and case-control studies assessing first-trimester PV or vascular indices in pregnancies developing PE or GH vs. normotensive controls were included. Study outcomes were presented using