- Transvaginal ultrasound (within 24 hours of FETO balloon insertion procedure) It is standard of care to have all patients receiving fetal therapy that require delivery at Johns Hopkins Hospital transfer prenatal care to the Center for Fetal Therapy. For this study, pregnant woman will transfer care prior to the FETO procedure and social work will facilitate relocation to a radius of 30 minutes from Johns Hopkins Hospital while the balloon is in place and the fetus has an occluded airway. Pregnant women are expected to have a support person with them and will be instructed to travel by car or taxi directly to Johns Hopkins Hospital in the event of onset of labor or suspected preterm rupture of membranes.