ObjectiveFew fetal malformations benefit from in utero surgery. One of the major drawbacks of fetal surgery is preterm premature rupture of membranes (PPROM). Morbidity associated with congenital diaphragmatic hernia (CDH) is primarily respiratory but also gastrointestinal and induced prematurity are likely to worsens those complications. To assess whether or not the cannula insertion site on the maternal abdomen during fetoscopic endoluminal tracheal occlusion (FETO) was associated with PPROM before balloon removal.MethodsThis multicenter retrospective study was conducted on consecutive pregnancies with isolated left‐ or right‐sided CDH fetuses who underwent FETO in 4 centers between January 2009 and January 2021. The insertion site for balloon insertion was categorized as above or below the umbilicus. One propensity score was analyzed in both groups: entry above the umbilicus and entry below, to calculate an average treatment effect (ATE) by inverse probability of treatment weighting (IPTW). Afterwards, one logistic regression and one Cox proportional hazard regression that included the ATE weights were performed to examine the effect size of entry point on the frequency and timing of PPROM prior to the balloon removal procedure.ResultsA total of 294 patients were included. Mean gestational age (GA) at PPROM was 33.50±2.01 weeks of gestation (WG) and the mean rate of PPROM was 25.8% (76/294). GA at FETO was later in the “below umbilicus” group (29.0±1.25 WG vs 29.47±1.29 WG, p=0.002) and the duration of FETO was longer in the “above umbilicus” group (14.49 min [interquartile range‐IQR: 8.00‐21.00] vs 11.00 min [IQR: 7.00‐14.49], p=0.002). After balancing for possible confounding factors, entry point below the umbilicus did not increase the risk of PPROM (adjusted OR: 1.56, 95%CI: [0.89‐2.74], p=0.120) and had no effect on the time point at membrane rupture (adjusted HR: 1.56, 95% CI: [0.95‐2.55], p=0.080).ConclusionThere was no evidence that uterine entry site was correlated with the risk of PPROM before balloon removal.This article is protected by copyright. All rights reserved.