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

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.

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 mean difference (MD) with 95% confidence intervals (CIs) and heterogeneity among studies was assessed using I² statistics. Thirty-eight studies were included in the systematic review, and ultrasound was performed between 11 and 14 weeks of gestation in 36 studies. Significantly lower levels of PV were found in patients who developed PE (MD: −12.61, 95%CI: −19.05 to −6.17, P-value: 0.0001), and, interestingly, in patients who developed both early onset and late onset PE (MD: −20.61, 95%CI: −27.56 to −13.66, P-value < 0.00001, and MD: −11.89, CI95%: −17.00 to −6.78, P-value < 0.00001, respectively). Finally, significant lower levels of vascular indices were found in patients with PE (MD vascularization index: −4.69, 95%CI: −6.40 to −2.98, P-value <0.00001; MD flow index: −4.83, 95%CI: −6.59 to −3.07, P value < 0.00001; MD vascularization flow index: −1.98, 95%CI: −2.59 to −1.37, P-value <0.00001).

First-trimester placental volume and vascular indices are lower in pregnancies that subsequently develop PE, but not GH. These findings suggest potential clinical utility, pending prospective validation and standardized measurement.