The first human fetal surgery, performed in the 1950s, were fetal blood transfusions for Rh-positive babies whose red blood cells were under attack by the Rh-negative mother's immune system. Attempts to improve this technique via direct access to the fetus through an open uterus were unsuccessful, and open-womb fetal surgery was abandoned. The development of real-time ultrasound imaging in 1977 made intrauterine fetal surgery feasible: visual imaging permitted surgeons to accurately guide needles similar to those used for amniocentesis without the risk of damage to placenta or fetus. In the early 1980s, surgeons at several medical centers attempted closed-womb surgery to relieve fetal hydrocephalus (abnormal accumulation of fluid around the brain) by draining excess fluid. Although fluid could be drained, most babies were born with severe neurological defects. In 1981, pediatric surgeon Michael Harrison of the University of California at San Francisco developed a closed-womb shunting procedure to...