Ultrasound prediction of adverse perinatal outcome at diagnosis of late‐onset fetal growth restriction

OBJECTIVE: To evaluate the relationship between Doppler and biometric ultrasound parameters measured at diagnosis and perinatal adverse outcome in a cohort of late‐onset growth‐restricted (FGR) fetuses. METHODS: This was a multicenter retrospective study of data obtained between 2014 and 2019 including non‐anomalous singleton pregnancies complicated by late‐onset FGR (≥ 32 weeks), which was defined either as abdominal circumference (AC) or estimated fetal weight (EFW) < 10(th) percentile for gestational age or as reduction of the longitudinal growth of AC by over 50 percentiles compared to ultrasound scan performed between 18 and 32 weeks of gestation. We evaluated the association between sonographic findings at diagnosis of FGR and composite adverse perinatal outcome (CAPO), defined as stillbirth or at least two of the following: obstetric intervention due to intrapartum fetal distress, neonatal acidemia, birth weight < 3(rd) percentile and transfer to the neonatal intensive care unit (NICU). RESULTS: Overall, 468 cases with complete biometric and umbilical, fetal middle cerebral and uterine artery (UtA) Doppler data were included, of which 53 (11.3%) had CAPO. On logistic regression analysis, only EFW percentile was associated independently with CAPO (P = 0.01) and NICU admission (P < 0.01), while the mean UtA pulsatility index (PI) multiples of the median (MoM) > 95(th) percentile at diagnosis was associated independently with obstetric intervention due to intrapartum fetal distress (P = 0.01). The model including baseline pregnancy characteristics and the EFW percentile was associated with an area under the receiver‐operating‐characteristics curve of 0.889 (95% CI, 0.813–0.966) for CAPO (P < 0.001). A cut‐off value for EFW corresponding to the 3.95(th) percentile was found to discriminate between cases with and those without CAPO, yielding a sensitivity of 58.5% (95% CI, 44.1–71.9%), specificity of 69.6% (95% CI, 65.0–74.0%), positive predictive value of 19.8% (95% CI, 13.8–26.8%) and negative predictive value of 92.9% (95% CI, 89.5–95.5%). CONCLUSIONS: Retrospective data from a large cohort of late‐onset FGR fetuses showed that EFW at diagnosis is the only sonographic parameter associated independently with the occurrence of CAPO, while mean UtA‐PI MoM > 95(th) percentile at diagnosis is associated independently with intrapartum distress leading to obstetric intervention. © 2021 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.