Placental Pathology and Its Associations With Clinical Signs in Different Subtypes of Fetal Growth Restriction.

Objective: We evaluated placental alterations in different subtypes of fetal growth restriction (FGR) to determine any clinical associations.

Methods: FGR placentas classified according to the Amsterdam criteria were correlated with clinical findings. Percentage of intact terminal villi and villous capillarization ratio were calculated in each specimen. Correlations of placental histopathology and perinatal outcomes were studied. 61 FGR cases were studied.

Results: Early-onset-FGR was more often associated with preeclampsia and recurrence than late-onset-FGR; placentas from early-onset-FGR often had diffuse maternal (or fetal) vascular malperfusion and villitis of unknown etiology. Decreased percentage of intact terminal villi was associated with pathologic CTG. Decreased villous capillarization was associated with early-onset-FGR and birth weight below the second percentile. Avascular villi and infarction were more common when femoral length/abdominal circumference ratio was >0.26, and perinatal outcome was poor in this group.

Conclusion: In early-onset-FGR and preeclamptic FGR, altered vascularization of villi may have a key role in pathogenesis, and recurrent FGR is associated with villitis of unknown etiology. There is an association between femoral length/abdominal circumference ratio >0.26 and histopathological alterations of placenta in FGR pregnancies. There are no significant differences in the percentage of intact terminal villi between different FGR subtypes by onset or recurrency.