In utero intervention for fetal anomalies or abnormal placentation should only occur for conditions known to result in ongoing irreversible harm to the fetus or increased risk to the mother. For in utero fetal treatment procedures there should be evidence that potential harm from the fetal lesion is best mitigated by intervention at a gestational age with superior outcomes than ex utero neonatal treatment. Although most fetal anomalies are not amenable to in utero treatment, two conditions with significant evidence of improved outcomes include use of fetoscopic laser photocoagulation to treat twin-to-twin transfusion syndrome and mid-gestational in utero open fetal surgery to treat myelomeningocele. Minimally invasive fetal treatment techniques are typically performed under local or regional anesthesia, while open fetal procedures are done under general anesthesia. Successful fetal intervention requires extensive multidisciplinary planning and collaboration. In addition to anesthetic considerations employed for nonobstetric surgery during pregnancy, fetal anesthesia and analgesia, fetal monitoring, uterine relaxation, and preparation for emergent maternal and fetal events are all necessary. Future research into anesthetic techniques for various maternal-fetal procedures is key to optimizing clinical outcomes and advancing the field of fetal surgery and maternal-fetal medicine.

The uterus serves as an incubator for the fetus during pregnancy. Within this incubator, the placenta is the main connection between the mother and the fetus and is integral to the survival of the fetus as it is an important source of fetal nutrients and oxygen. The proper development of the placenta allows it to support the fetus throughout pregnancy and expulsion or removal of a normal placenta following delivery, helps prevent postpartum complications. Maintenance of uteroplacental flow during pregnancy and during fetal surgery is important for the survival of the fetus and especially for the remainder of the pregnancy following fetal surgery. Serial monitoring of umbilical artery flow, a marker for uteroplacental insufficiency, is helpful to monitor fetal well-being. Physiology of the fetus correlates with the different stages of development in different organs and in many instances changes at delivery. The prevention of pain or the effects of noxious stimuli during fetal surgery serves many benefits, which include but are not limited to, prevention of release of stress hormones which can play a role in preterm labor and also prevention of long-term neurodevelopmental effects in the fetus.