Mode of delivery according to Robson classification and perinatal outcomes in restricted and small for gestational age fetuses

Objective: To evaluate the mode of delivery according to Robson classification [RC] and the perinatal outcomes in fetal growth restriction [FGR] and small for gestational age [SGA] fetuses. Methods: Retrospective cohort study by analyzing medical records of singleton pregnancies from two consecutive years [2018 and 2019]. FGR was defined according to Delphi Consensus. The Robson groups were divided into two intervals [1-5.1 and 5.2-10]. Results: Total of 852 cases were included: FGR [n = 85], SGA [n = 20] and control [n=747]. FGR showed higher percentages of newborns < 1,500 grams [p<0.001] and higher overall cesarean section [CS] rates [p<0.001]. FGR had the highest rates of neonatal resuscitation and neonatal intensive care unit admission [p<0.001]. SGA and control presented higher percentage of patients classified in 1- 5.1 RC groups, while FGR had higher percentage in 5.2- 10 RC groups [p<0.001]. FGR, SGA and control did not differ in the mode of delivery in the 1-5.1 RC groups as all groups showed a higher percentage of vaginal deliveries [p=0.476]. Conclusion: Fetuses with FGR had higher CS rates and worse perinatal outcomes than SGA and control fetuses. Most FGR fetuses were delivered by cesarean section and were allocated in 5.2 to 10 RC groups, while most SGA and control fetuses were allocated in 1 to 5.1 RC groups. Vaginal delivery occurred in nearly 60% of FGR allocated in 1-5.1 RC groups without a significant increase in perinatal morbidity. Therefore, the vaginal route should be considered in FGR fetuses.