Surgery to correct spina bifida in the womb.
This surgery generally takes place around 24 weeks, and can potentially be life-threatening to the fetus. Still, the surgery far more often causes significantly improved quality of life after birth, even though not all of the problems that spina bifida entails will be gone.
Spina bifida is caused by faulty cell signaling when the neural pores are closing very early on in pregnancy. There is NO genetic defect in the embryo/fetus, so when the mistake that the embryo made is corrected by a surgeon, the body will continue its formation as if it was normal, and not try to revert to the former state with a cleft spine.
The fact that there is rarely a heavy genetic impact in spina bifida cases also means that when patients with spina bifida or spina bifida occulta get pregnant (which many less-affected patients do), they’re likely not going to pass their traits on to their children. Almost all genetically-caused neural tube defects are quickly fatal.