No patients could be recruited and randomized due to other center offering backdoor for treatment.

Diaphragmatic hernia detected in fetal life carries a high risk for postnatal demise due to lung underdevelopment. Clinical experience from prospective controlled non-randomized case series with fetoscopic tracheal balloon occlusion has seen improved survival rates in contrast to untreated controls. Therefore, the purpose of this randomized clinical trial is to provide further evidence about the efficacy and safety of the prenatal interventional approach. Primary outcome measure is postnatal survival to discharge from hospital treatment.

Inclusion Criteria:

• Pregnant women from European countries carrying fetuses with congenital right or left diaphragmatic hernias
• Normal karyotype, no further severe anomalies on prenatal ultrasound study
• Fetal liver herniation into the chest, Lung-to-head ratio of ≥0,40 ≤0,84 between 30+0 - 33+5 weeks+days of gestation

Exclusion Criteria:

• Any maternal disease or condition that would result in an increased risk to her personal health from the experimental procedure
• Abnormal fetal karyotype
• Further severe fetal anomalies on prenatal ultrasound