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