Fetal foramen ovale restriction in pregnancy: echocardiographic characteristics and perinatal outcomes

Objective Fetal foramen ovale restriction (FO-R) is an abnormal intracardiac flow disorder that may affect fetal cardiac hemodynamics and perinatal management. This retrospective cohort study aimed to characterize the echocardiographic features, associated abnormalities, and perinatal outcomes of pregnancies complicated by fetal FO-R, providing clinical evidence for obstetric decision-making.Methods A total of 283 fetuses diagnosed with FO-R by fetal echocardiography were enrolled. The diagnostic criteria were defined as a foramen ovale (FO) diameter <3 mm and a Doppler flow velocity >40 cm/s. Maternal clinical data, fetal echocardiographic findings, delivery details, and neonatal follow-up outcomes were collected and analyzed systematically.Results The incidence of FO-R was 1.88% among all fetal echocardiographic examinations. The median gestational age at diagnosis was 35 + 4 weeks, with 11.7% of cases diagnosed before 32 weeks of gestation. Coexisting pregnancy complications or fetal abnormalities were observed in 51.6% of cases, while 41.2% presented with isolated FO-R. Right heart enlargement was the most common associated cardiac finding (74.6%). The cesarean delivery rate was 64.7%, with fetal distress as the leading indication (24.0%). Multivariate analysis showed that FO diameter, timing of diagnosis, and presence of right heart enlargement did not significantly influence the delivery mode (all p > 0.05). Among 240 neonates with complete follow-up data, 27.1% had postnatal cardiac abnormalities, 93.8% of which resolved spontaneously within one year. Only 1.7% of neonates had persistent congenital heart defects.Conclusion Fetal FO-R is mostly diagnosed in the third trimester and is frequently associated with right heart enlargement. Importantly, FO-R does not independently require cesarean delivery or preterm birth. Neonatal outcomes of fetuses with FO-R are generally favorable, with a high rate of spontaneous resolution of postnatal cardiac findings, which supports conservative obstetric management for most cases.