(107) Under the Microscope: A Closer Look at Placental Histological Findings in Early-Onset Fetal Growth Restriction

Early-onset fetal growth restriction (EOGFR) is associated with histopathological abnormalities on both the maternal and fetal side of the placenta. Our aim was to evaluate placental histological features and correlate with perinatal outcomes.

Study Design:

A single-centre retrospective cohort study was performed on EOFGR diagnosed between 18-32 weeks’ gestation at the largest European maternity hospital from July 2016 - June 2022. Delphi consensus criteria were used for definition, and genetic, structural or infectious causes were excluded. Placental histological features were compared to antenatal characteristics and pregnancy outcomes using Chi-square and Wilcoxon rank test. Stepwise multivariate logistic regression was used to determine the most important independent predictors of maternal vascular malperfusion (MVM).

Results:

There were 341 cases of uteroplacental EOFGR, with a 95% livebirth rate (325/341). 66% (225/341) of placentas were sent for histological analysis. MVM was the most common associated abnormality (60%, 136/225) with fetal vascular malperfusion (FVM) present in 30% (67/225). 14% (31/225) of cases had both MVM & FVM present.

Table 1 correlates MVM and FVM with pregnancy outcomes. Pre-eclampsia (PET) and umbilical artery Doppler (UAD) abnormality remain strong predictors of MVM after adjustment for the effects of each other (PET, aOR 5.5 (95% CI, 2.2-13.6; p< 0.001); Abnormal UAD, aOR 3.0 (95% CI, 3.0-5.9; p 0.001)). 

Placental hypoplasia was present in 71% (160/225) and this was significantly associated with MVM (p=0.005) (Figure 1). Mean fetoplacental ratio was 5.7 (SD 1.65) and this was not associated with either MVM (p=0.118) or FVM (p=0.836).

Conclusion:

MVM is the most frequent placental finding in EOFGR and is more closely associated with preterm delivery, PET and adverse outcome, whereas FVM showed no correlation with these factors, suggesting two distinct pathological processes underlying EOFGR. Given their difference in outcomes, placental histological assessment is critical following any pregnancy affected by EOFGR, to inform monitoring and care of future pregnancies.