When a woman is raped, or suffers from German measles during her pregnancy, possibly leading to a disability to the baby when it is born, is the abortion of a necessary nature sinful?

I’d like to ask you about necessary abortions. For example, when a woman is raped, or suffers from German measles during her pregnancy, possibly leading to a disability to the baby when it is born, is the abortion of a necessary nature sinful or not?