The purpose of this study is to evaluate successful placement and removal of Fetoscopic Endoluminal Tracheal Occlusion (FETO) device in cases of intrathoracic liver herniation with isolated left congenital diaphragmatic hernia (LCDH) with Observed/Expected (O/E) Lung to Head Circumference Ratio (LHR) < 30% or isolated right congenital diaphragmatic hernia (RCDH) with O/E LHR < 45%,to compare survival to discharge from the neonatal intensive care units (NICU), between fetuses with intrathoracic liver herniation and isolated LCDH with O/E LHR < 30% that receive FETO procedure performed at 27 weeks 0 days to 29weeks 6 days of gestation to those with intrathoracic liver herniation, isolated LCDH and o/e LRH < 30% that undergo expectant management, to compare the neonatal survival rate to discharge from the neonatal intensive care units (NICU), between fetuses with intrathoracic liver herniation, isolated RCHD with o/e LHR < 45% that undergo FETO procedure performed at 27 weeks 0 days to 29 weeks 6 days gestation to those with intrathoracic liver herniation, isolated RCHD and o/e LHR < 45% that elect to proceed with expectant management, to evaluate the frequency of maternal and fetal complications associated with FETO procedure, to evaluate whether the FETO procedure is associated with reduced long-term mortality and morbidities in isolated LCDH survivors with o/e LHR <30% when compared to isolated LCDH with o/e LRH <30% that undergo expectant management where all fetuses were found to have intrathoracic liver herniation and to evaluate whether the FETO procedure is associated with reduced long-term mortality and morbidities in isolated RCDH survivors with o/e LHR ≤ 45% when compared to isolated RCHD with LHR < 45% that undergo expectant management where all fetuses were found to have intrathoracic liver herniation

Inclusion Criteria:

• Pregnant women who are able to consent
• Singleton pregnancy
• Normal Karyotype, chromosomal microanalysis (CMA) with non-pathologic variants, Whole exome sequencing (WES) or whole genome sequencing (WGS) . Results by fluorescence in situ hybridization (FISH) will be acceptable if the patient is > 26 weeks
• Gestational age at enrollment is prior to 296 wks.
• Intrathoracic liver herniation
• Isolated left CDH with o/e LHR < 30% at enrollment (180 to 295 wks.). or
• Isolated RCDH with o/e LHR < 45% at enrollment (180 to 295 wks.)
• Cervical length by transvaginal ultrasound > 20 mm within 24 hours prior to FETO procedure
• Patient meets psychosocial criteria
• Informed consent understood

Exclusion Criteria:

• History of natural rubber latex allergy

• Preterm labor, cervix shortened (<20 mm at enrollment or within 24 hours of FETO balloon insertion procedure) or uterine anomaly strongly predisposing to preterm labor, placenta previa.

• Psychosocial ineligibility, precluding consent:

  1. Inability to reside within 30 minutes of University of Texas Health Science Center at Houston Fetal Center
  2. The patient does not have a support person (e.g., spouse, partner, mother) available to stay with the patient for the duration of the pregnancy at UTHealth Houston Fetal Center

• Bilateral CDH, isolated left sided CDH with O/E LHR ≥ 30% (measured at 180 to 295 weeks), isolated right sided CDH with O/E LHR > 45% (measured at 180 to 295 weeks), as determined by ultrasound

• No liver herniation into thoracic cavity

• Additional fetal anomaly and chromosomal abnormalities by ultrasound, MRI, or echocardiogram at the fetal treatment center. Exclude chromosomal abnormalities, associated anomalies recognized to alter survival prognosis (i.e., CDH and congenital heart disease) or presence of an underlying genetic syndrome (i.e., Fryns).

• Maternal contraindication to fetoscopic surgery or severe maternal medical condition in pregnancy

• History of incompetent cervix with or without cerclage

• Placental abnormalities (previa, abruption, accreta) known at time of enrollment

• Maternal-fetal Rh isoimmunization, Kell sensitization or neonatal alloimmune thrombocytopenia affecting the current pregnancy

• Maternal HIV, Hepatitis-B, Hepatitis-C status positive because of the increased risk of transmission to the fetus during maternal-fetal surgery. If the patient's HIV or Hepatitis status is unknown, the patient must be tested and found to have negative results before enrollment

• Uterine anomalies such as large or multiple fibroids or Mullerian duct abnormality

• There is no safe or technically feasible fetoscopic approach to balloon placement

• Participation in another intervention study that influences maternal and fetal morbidity and mortality. or participation in this trial in a previous pregnancy