In Utero Diagnosis of Premature Closure of the Foramen Ovale: A Retrospective Case Series Analyzing Neonatal Interventions and Maternal Factors.

Isolated premature closure of the foramen ovale (FO) in utero is a rare condition. The impact on fetal hemodynamics and postnatal outcomes varies greatly, with most severe outcomes including: arrhythmias, heart failure, and hydrops fetalis. We sought to analyze the types of interventions that neonates diagnosed prenatally with isolated premature FO closure receive post-birth and to identify associated maternal factors. A retrospective chart review was conducted at an urban level II fetal center from January 1st, 2018 to April 30th, 2025. 34 subjects were identified with premature closure of the FO on fetal echocardiogram. Of those, 100% received a postnatal echocardiogram and 56% required cardiology follow-up with a repeat echocardiogram. Postnatal echocardiogram findings included restricted patent FO with left-to-right shunt, small ASD, aneurysmal atrial septum, and normal imaging; none showed complete closure of the FO. Of the neonates in this review, 62% required neonatal intensive care unit (NICU) admission, 29% required continuous positive airway pressure, 21% required intravenous fluids, and 6% required milrinone; no subjects required inhaled nitric oxide or extracorporeal membrane oxygenation (ECMO). Potential maternal associations identified included diabetes (26%), hypertension (18%), and aspirin use (35%). We conclude that prenatal diagnosis of premature FO closure is essential given all the subjects required postnatal echocardiogram monitoring and access to pediatric cardiology. Future studies should broaden the sample size across multiple institutions to better identify predisposing maternal factors and determine updated guidelines for prenatal echocardiogram screening to monitor for premature closure or restriction of the FO.