Fetoscopic Endoluminal Tracheal Occlusion

Inclusion Criteria: 1. A subject is defined as a female (18 years or older) who is pregnant. 2. The pregnancy must be a singleton pregnancy. 3. The CDH must be left-sided. 4. The CDH must be severe (Observed to Expected Lung to Head Ratio - O/E LHR - \< 25% from U/S measurements). 5. No associated lethal anomalies (other than the CDH), no pathogenic variants on microarray, and no pathologic findings on karyotype. 6. Fetal echocardiogram with changes expected with CDH and no major structural cardiac defects. 7. Gestational age at time of balloon placement between and including 27 weeks 0 days and 29 weeks 6 days. 8. Cervix length longer than 20 mm at pre-balloon placement evaluation. 9. Acceptance of responsibility to stay locally (within 15 minutes) of MWFCC and Children's Minnesota - Minneapolis. 10. Written consent must be obtained. 11. Must meet psychosocial criteria including appropriate family/friend support during stay with balloon in place (cannot stay without additional helper), no current illicit drug use, no over-the-counter drug abuse, and no ineffectively treated DSM-IV diagnoses. Exclusion Criteria: 1. Twin or higher order gestation 2. Not able to consent 3. Right-sided or bilateral CDH 4. Additional fetal or genetic abnormalities that would impact care after delivery or be known to have an impact on outcome 5. Maternal isoimmunization or neonatal alloimmune thrombocytopenia 6. Balloon not able to be placed prior to 30 weeks gestation 7. CDH O/E LHR 25% or greater 8. Maternal factors precluding safe fetal surgery (maternal cardiac findings not safe for anesthesia, maternal morbid obesity precluding safe usage of the equipment required for entry into the uterus, spontaneous preterm delivery prior to 36 weeks) 9. Maternal HIV, Hepatitis B with positive surface antigen, Hepatitis C with presence of virus in maternal blood due to risks of fetal transmission during procedures 10. Short cervix (20 mm or less) 11. History of incompetent cervix or uterine anomaly predisposing to preterm labor 12. Significant placental abnormalities (abruption, chorioangioma, accrete) known at the time of enrollment and/or surgery 13. History of natural rubber latex allergy 14. No safe or feasible fetoscopic approach to balloon placement 15. Inability to relocate to within 15 minutes of MWFCC/Children's Minnesota