On the Frum Skeptics Group, one of the members asked about our political views on abortion. This is what I answered:
I have mixed feelings. I believe that human life, even potential human life, has value and should not be treated disrespectfully or callously. So I am against the use of abortion as a shallow form of birth control.
On the other hand, a mere potential human life doesn't have the same rights as a full-fledged existing human life, i.e. the mother. As such, if the mother's interests are seriously impaired by a pregnancy then I think an abortion can be justified.
There is also the importance of what stage of the pregnancy can abortions still be permitted. Most people will agree that for life and death situations, the mother's life takes precedence of the fetus' and so even in the ninth month that kind of abortion would be permitted. Or up until the head exits the body, as the Gemara would put it.
In all other cases though the third trimester should essentially treat the fetus as a baby with a right to life. The first and second are more flexible with the earlier in the pregnancy being progressively more flexible (with given understanding of well-known significant points achieved during fetal development). Morally I think that one needs a better justification for the later in the pregnancy, but legally, personal choice should be the rule.
Now, whether I personally would ever perform an abortion on someone else, that is a separate issue. And I think that except for life and death situations for the mother, I would probably not want to perform elective abortions.