Surgery on babies still in the womb has long largely been restricted to those who would die otherwise, but a landmark study is likely to lead to a surge of research into fetal surgery to treat birth defects. Surgeons found that repairing spina bifida—a debilitating spinal condition that 1,500 babies are born with annually—in the womb helps avoid the brain damage and paralysis that often result when the condition isn't treated until after birth, NPR reports.
During the surgery, doctors operate on a four-inch long fetus, putting a protruding, roughly raisin-size piece of spinal cord back inside the fetus's body. The study reviewed 183 pregnancies, and found that children who had the surgery before birth were twice as likely to walk unaided later: At age 3, 42% could walk, versus 21% who did not have the prenatal operation. "This is the first time that fetal surgery has ever been attempted and validated for what we think of as a non-fatal birth defect," says one of the study's authors. There were medical downsides for both mothers and infants (for instance, 80% of the babies who had the surgery were delivered prematurely, compared to 15% of those who did not), but experts describe the study as a huge step in the right direction, the New York Times notes.