Risk factors for adverse perinatal outcomes in pregnancies with early- and late-onset extreme fetal growth restriction, estimated fetal weight ≤ 1st centile: A multicenter retrospective study

OBJECTIVE: To investigate the risk factors associated with adverse perinatal outcome in early-onset (<32 weeks) and late-onset (≥32 weeks) extreme fetal growth restriction (FGR), defined as estimated fetal weight (EFW) ≤ 1st centile. MATERIALS AND METHODS: A multicenter, retrospective cohort study was performed on pregnancies complicated by early- and late-onset extreme FGR within a week of delivery between 2018 and 2021. Doppler indices were converted as percentile adjusted for gestational age (GA). Composite adverse perinatal outcome (APO) was defined as fetal or neonatal death or at least one of the after severe perinatal morbidities: respiratory distress syndrome, bronchopulmonary dysplasia, intraventricular hemorrhage, proven sepsis or necrotizing enterocolitis. Odds ratios (OR) with 95% confidence intervals (CI) were estimated using multivariable logistic regression. RESULTS: Overall, 261 cases were included: 135 cases of early- and 126 cases of late-onset extreme FGR. The perinatal mortality rate was 7.4% in early- and 1.6% in late-onset extreme FGR. Composite APO was 54.1% and 12.7% in the early- and late-onset extreme FGR groups, respectively. The risk factors for the composite APO were GA at delivery (aOR 0.52, 95% CI 0.36-0.74), the presence of non-reassuring cardiotocography (aOR 0.34, 95% CI 0.12-0.95), and EFW within 1 week before delivery (aOR 1.003, 95% CI 1.000-1.005) in early-, and GA at delivery (aOR 0.79, 95% CI 0.64-0.98) and diabetes during pregnancy (aOR 1.87, 95% CI 1.47-9.58) in late-onset extreme FGR. CONCLUSIONS: Composite APO in early- and late-onset extreme FGR were comparable. GA at delivery may be the significant risk factor for the composite APO in early- and late-onset extreme FGR.