EP08.10: Sonographic surveillance and perinatal outcomes among pregnancies with periviable fetal growth restriction

Fetal growth restriction (FGR) is associated with increased perinatal morbidity and mortality. The risk for perinatal morbidity and mortality is inversely related to gestational age (GA) at diagnosis, particularly when the diagnosis is made at < 28 weeks gestation. This study aims to compare perinatal outcomes between fetuses with periviable FGR (pFGR) who did and did not undergo weekly sonographic surveillance. A retrospective cohort study was conducted at 2 tertiary care centres between 1/2017 and 6/2023. pFGR was defined as a singleton gestation with an estimated fetal weight (EFW) < 500g, a GA between 22 0/7 and 27 6/7 weeks gestation, and an EFW measuring < 10th percentile for GA. Fetuses with known structural anomalies and/or genetic abnormalities were excluded. The surveillance cohort initiated weekly Doppler surveillance while the growth cohort underwent serial growth assessment between 22-28 weeks gestation. The primary outcome was livebirth. Secondary outcomes included obstetric and sonographic outcomes. Student's t-test for independent samples and chi-square (or Fisher's exact test) were performed to compare quantitative and categorial variables, respectively. Of 224 gestations included for analysis, 81(36.2%) underwent weekly sonographic surveillance. Chronic hypertension (18.5% v 9.1%, p = 0.04), pregestational diabetes (8.6% v 2.8%, p = 0.05), and prior history of intrauterine fetal demise (IUFD, 8.6% v 2.1%, p = 0.02) were more common among the surveillance cohort. There was no difference in livebirth rate between cohorts. A greater proportion of the surveillance cohort developed a hypertensive disorder of pregnancy (HDP, 45.7% v. 25.2%, p < 0.05) and delivered via Caesarean section (56.8% v. 32.2%, p < 0.05). Despite no difference in livebirth rate, the surveillance cohort experienced a greater rate of perinatal complications. This observational cohort study suggests that individual patient risk factors may have driven stratification of higher-risk patients into the surveillance cohort.