Self-defense is defined as the right to prevent suffering force or violence through the use of a sufficient level of counteracting force or violence.
No fetus could be said to be attacking or using force against the mother, only that its very existence puts the mother's life at risk, either because she has sustained a trauma or because of some dangerous condition that has developed in the mother's body, or where the pregnancy is ectopic.
No doctor has ever referred to a medically necessary termination as an act of defense, but rather an action to save the mother's life. Also, the mother is not the one performing the procedure, so it's not self anything.
Try again.