Are Early and Late Preeclampsia Distinct Subclasses of the Disease--what Does the Placenta Reveal?

Objective: To compare histopathological differences in placentas from early- and late-onset preeclampsia, as well as late-onset preeclampsia and normal term deliveries.

Methods: This prospective study was performed at Tygerberg Hospital, a secondary and tertiary referral center in South Africa. Placentas from 100 women, 25 each with early and late-onset preeclampsia, and an equal number of controls matched for gestational age, underwent routine preparation and were evaluated independently by two pathologists in a strictly predetermined, standardized manner.

Results: Compared to late preeclampsia, placentas in the early preeclampsia group were smaller (p < 0.01), had more infarction (odds ratio [OR] = 4.03, 95% confidence interval [CI] = 1.2-13.5) and inappropriate maturation (OR = 16.62, 95% CI = 4.1-68.0). Placentas from the late-onset preeclampsia group showed increased decidual arteriopathy (OR = 5.09, 95% CI = 1.45-17.92) and abruptio placentae (OR = 5.41, 95% CI = 1.01-28.79) compared to controls.

Conclusions: The early- and late-onset preeclampsia placentas showed clear histopathological differences, whereas late-onset preeclampsia and normal term placentas differed less. These findings support the contention that early- and late-onset preeclampsia are different subclasses of disease.