One exception are certain vaccines – including some for mumps, rubella, polio and chicken pox – that were cultured on abortion-derived fetal tissues years ago. While the abortion was intrinsically evil, there is such a distance from those who aborted the babies to those who use the vaccines that few theologians assess a sinful charge against those who vaccinate their children with them. Also, the vaccines prevent such evils that it would be worse for the parents to avoid vaccinating their children than to abstain. Now, where vaccines are available that are not derived from aborted tissue, that’s preferable.

Procedures that result in the death of an unborn baby are allowed in extreme circumstances such as ectopic pregnancies and other instances where the life of the mother is directly threatened.
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Sterilization for the purpose of preventing procreation (i.e., you can have a hysterectomy if you have cancer and the procedure will save your life, but you can’t have one simply to prevent pregnancy).

IVF, GIFT, ZIFT, IUI, surrogacy and other forms of "fertility treatment" that lead to the conception of a child with third-party interference and without sexual intercourse between the husband and wife. Fertility treatments such as dilating clogged tubes, assisting sperm motility, etc. that enable a couple to conceive a child through intercourse are fine, however.

Euthanasia (such as denying a handicapped person food and water or giving a person doses of morphine that they don’t need in order to hasten death…which actually happens with shocking regularity).

Gender reassignment surgery and other forms of self-mutilation.
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