Risk factors associated with fetal growth restriction in pregnancies complicated by thick placenta

To identify risk factors affecting the occurrence of fetal growth restriction (FGR) in cases of thick placenta.

The retrospective study included 128 women who gave birth with a diagnosis of thick placenta between February 2016 to September 2022. Based on FGR (defined as birth weight less than the 10th percentile for gestational age), the participants were divided into FGR group and non-FGR group. Data included maternal demographic characteristics, pregnancy and placental parameters, and neonatal outcomes were analyzed.

There was no significant difference regarding maternal demographic characteristics within two groups (P > 0.05). The rate of preeclampsia and abnormal umbilical artery pulsatility index was significantly higher in FGR group compared with non-FGR group (P < 0.05); A trend of gradual growth of placental thickness and thinner thickness of initial-onset thick placenta were more frequently to see in FGR group (P < 0.05). Higher rate of worse composite neonatal outcome was noted in the FGR group as compared with non-FGR group (P < 0.05). Univariate logistic regression analysis found that the emergence of preeclampsia, abnormal umbilical artery pulsatility index, a trend of gradual growth of placental thickness and reduced thickness of initial-onset thick placenta has a positive relation with the occurrence of FGR. The highest area under curve (AUC) of thickness of initial-onset thick placenta (cutoff = 50.5 mm) for predicting FGR was 0.715. The AUC could be improved to 0,798, 0.821, 0.740 when combined with preeclampsia, abnormal umbilical artery pulsatility index, and a trend of gradual growth of placental thickness, respectively. The AUC of thickness of initial-onset thick placenta combined with preeclampsia and abnormal umbilical artery pulsatility index to predict FGR was the highest (AUC=0.869).

Thickness of initial-onset thick placenta combined with preeclampsia and abnormal umbilical artery pulsatility index is expected to be valid and reliable predictors for FGR prediction.