This is a single site pilot trial to assess the feasibility and safety of treating severe CDH with Fetal Endoscopic Tracheal Occlusion with the Goldballoon Detachable Balloon (GOLDBAL2) along with the Delivery Microcatheter (BALTACCI-BDPE100) at UC Davis Medical Center. The study will enroll pregnant women that meet study criteria. Participants will have placement of FETO between gestational age at 27 weeks plus 0 days and 29 weeks 6 days. The timing for removal of FETO will ideally be between 34 weeks 0 days and 34 weeks and 6 days but ultimately decided by the Fetal Diagnosis and Treatment Center at UC Davis Medical Center.

This study requires that study participants live within 30 minutes of the UC Davis Medical Center in order to maintain weekly follow up appointments while the balloon is in place and up to delivery. Additionally, there are lifestyle considerations where participants would be unable to carry on normal daily activities including exercise and sexual intercourse, not be able to work the remainder of the pregnancy, as well as have a support person that is available to stay with such as a spouse, friend, partner, parent.

Inclusion Criteria:

1. Provision of signed and dated informed consent form

2. Stated willingness to comply with all study procedures and availability (meets psychosocial criteria below) for the duration of the study

3. Pregnant women, age 18 years and older

4. Singleton pregnancy

5. No pathogenic variants on microarray or pathologic findings on karyotype

6. Fetal echocardiogram with changes expected with CDH and no major structural cardiac defects

7. Fetal CDH (left or right) with severe pulmonary hypoplasia, defined as o/e LHR <25% with liver up

8. Gestational age at FETO procedure: if o/e LHR <25% will be done at 27 weeks plus 0 days to 29 weeks plus 6 days

9. Meets psychosocial criteria

   • Willing to reside within 30 minutes of UC Davis Medical Center and ability to maintain follow up appointments
   • Patient has a support person (e.g. spouse, partner, friend, parent) that is available to stay with her for the duration of the pregnancy near the UC Davis Medical Center.
   • Willing to comply with restrictions of daily living including inability to exercise, have intercourse, or return to work

Exclusion Criteria:

1. Adults unable to consent

2. Prisoners

3. Multi-fetal pregnancy

4. History of latex allergy

5. History of preterm labor or incompetent cervix (requiring cerclage), short cervix (<20mm), or uterine anomaly predisposing to preterm labor

6. Psychosocial ineligibility

   • Inability to reside within 30 minutes of UC Davis Medical Center or inability to maintain follow up appointments
   • Social work will meet with each patient to evaluate the social situation and support system. Identifiable issues of social instability or compliance with the protocol will exclude her as a potential candidate.

7. Bilateral CDH, unilateral CDH with o/e LHR > 25% or unilateral CDH with o/e LHR <25% but liver completely down in abdomen

8. Additional fetal or genetic abnormalities that would impact care after delivery or be known to have an impact on outcome

9. Maternal contraindications to elective fetoscopic surgery

10. Significant placental abnormalities (abruption, chorioangioma, accreta) known at time of enrollment and/or surgery

11. Maternal isoimmunization or neonatal alloimmune thrombocytopenia

12. Maternal HIV, Hepatitis B with positive surface antigen, Hepatitis C with presence of virus in maternal blood due to risk of fetal transmission during the procedure

13. No safe or feasible fetoscopic approach to balloon placement