Placental Vascularization in Early Onset Small for Gestational Age and Preeclampsia

The objective was to determine whether chorionic villous vascularization is diminished in cases of early onset (<34 weeks) small for gestational age (SGA) and/or preeclampsia (PE). Placental morphometrical measurements were performed in 4 gestational-age-matched groups complicated by SGA, SGA with PE, PE, and spontaneous preterm delivery without SGA or PE as the reference group. Using a video image analysis system, in randomly selected intermediate and terminal villi, the stromal area and the following villous vascular parameters were manually traced and analyzed: number of total, centrally and peripherally localized vessels, vascular area, and vascular area density. No differences were observed in intermediate and terminal villous vascular area. Preeclampsia was associated with smaller terminal villous stromal area (reference 2299 mm 2, SGA 2412 mm 2, SGA + PE 2073 mu m(2), and PE 2164 mu m(2), P=.011), whereas SGA was associated with an increased terminal villous vascular area density (reference 26.1%, SGA 35.7%, SGA + PE 33.4%, and PE 32.0%, P=.029). Compared with preserved flow, lower terminal villous vascular area density was found in cases with absent or reversed end-diastolic (ARED) umbilical artery flow (39.3% vs 30.3%, P=.013). These data demonstrate that villous vascularization was not influenced by PE, whereas in terminal villi an increased vascular area density was associated with SGA. Lower terminal villous vascular area density was associated with ARED flow in SGA pregnancies, indicating an increased risk of fetal compromise.