Placental Pathology in preeclampsia and gestational hypertension; A comparative study

To evaluate placental histopathological lesions in hypertensive disorders of pregnancy and their association with maternal and fetal outcomes.

This cross-sectional study was conducted in the Departments of Pathology and Gynecology & Obstetrics, Dow Hospital, Dow University of Health Sciences, from January-December 2021. Seventy-six pregnant women were included: preeclampsia (n=29), gestational hypertension (n=24), and normotensive controls (n=23). Placentae were examined microscopically, and lesions were classified according to the Amsterdam criteria into maternal vascular malperfusion (MVM), fetal vascular malperfusion (FVM), and inflammatory lesions. Association with clinical group was assessed by Poisson regression analysis, expressed as incidence rate ratio (IRR).

Placental lesion categories were significantly different across the clinical groups (p=0.018). MVM lesions, including accelerated villous maturation, distal villous hypoplasia, villous infarction, decidual arteriopathy, and low fetal-to-placental weight ratio, were increased in preeclampsia (IRR=4.4, p<0.001) and gestational hypertension (IRR=2.5, p=0.005). FVM showed no association. Inflammatory lesions demonstrated a borderline association with preeclampsia (IRR=3.2, p=0.039). Adverse maternal outcomes (eclampsia, ICU admission) and fetal outcomes (low birthweight, NICU admission, stillbirth) were significantly frequent in preeclampsia (p=0.002).

Maternal vascular lesions were significantly increased, with a 4.4-fold increase in preeclampsia and a 2.5-fold increase in gestational hypertension, compared with normotensive pregnancies. These findings highlight the central role of maternal vascular pathology in the pathogenesis of hypertensive disorders and adverse maternal and fetal outcomes. We recommend high-quality antenatal care for early detection of hypertensive disorders and placental histopathology as a valuable diagnostic tool.