The placental factor in early- and late-onset normotensive fetal growth restriction

Objective: Our objective was to investigate the placental component in early- and late-onset fetal growth restriction (FGR) compared to placentas from neonates appropriate for gestational age (AGA). Study design: Placentas from normotensive women who gave birth at 24-42 weeks to neonates with a birth-weight below the 10th percentile (FGR group), or to healthy AGA neonates (AGA group), were analyzed. Placental lesions were classified to lesions related to maternal underperfusion, lesions consistent with fetal thrombo-occlusive disease and inflammatory lesions. Findings were compared between patients who delivered ≤34 weeks (early-onset FGR) or >34 weeks (late-onset FGR) and controls with AGA neonates. Results: The early-onset FGR group (n = 24) had a higher rate of placental vascular lesions related to maternal underperfusion than the late-FGR group (n = 334) (41.7% vs. 8.7%, P < 0.001) and more villous lesions related to maternal underperfusion than the preterm AGA group (n = 68) (70.8% vs. 5.9%, P < 0.001). The late-onset FGR group had more placental villous lesions related to maternal underperfusion (57% vs. 19% P < 0.001) and more lesions consistent with fetal thrombo-occlusive disease (26.3% vs. 8.5%, P < 0.001) than the term AGA group (n = 153). Conclusion: Early- and late-onset FGR have different placental pathology compared with AGA controls, suggesting that a combination of fetal and maternal vascular compromise is more dominant in the late-onset FGR, rather than more severe maternal vascular compromise in early-onset FGR.