Our experimental and clinical experience with open fetal surgery has provided invaluable lessons regarding optimal maternal-fetal anesthesia, hysterotomy, fetal exposure techniques, fetal monitoring, reliable steps for in utero repair of life-threatening defects, and secure methods for uterine closure. Most importantly, open fetal surgery has been performed in both nonhuman primates and in the initial series of clinical cases with acceptable maternal safety and without detectable adverse effects on later reproduction.