The neonatal mortality rate in cases with severe isolated congenital diaphragmatic hernia is higher than 90% due to severe pulmonary hypoplasia. Many studies have suggested that fetal tracheal occlusion may increase lung volumes and therefore reducing the risk for severe pulmonary hypoplasia and by consequence the risk for neonatal death.

The main objective of the present study is to evaluate if fetal tracheal occlusion improves survival rate in those cases that are followed in our hospital, by conducing a randomized trial.

Fetuses will be randomly allocated in two groups: 1. for fetal tracheal occlusion at 26-28 weeks (FETO group) or 2. Postnatal therapy only (Control)

Main outcome: Survival rate in both groups Second outcomes: Postnatal diagnosis of severe pulmonary arterial hypertension, percentage of newborns in each group that will have clinical conditions for neonatal surgical repair of the diaphragmatic defect, fetal lung responses (increase of fetal lung size), maternal and obstetrical complications (prematurity, preterm rupture of the membranes, maternal hemorrhage and infection).

Inclusion Criteria:

• ultrasound diagnosis of congenital diaphragmatic hernia
• fetuses at gestational age between 24 and 28 weeks
• absence of chromosomal and/or other structural anomalies (isolated congenital diaphragmatic hernia)
• severe congenital diaphragmatic hernia defined by lung-head ratio < 1.0 and more than 1/3 of liver herniated into fetal thorax and observed/expected fetal total lung volume < 0.35
• patient's consent to participate in the present study

Exclusion Criteria:

• Patient's refusal to participate in the study after allocation
• Preterm labor diagnosed before the procedure
• Preterm rupture of membranes before fetal intervention