I've had six babies. A number of my friends have more. The "physical risks" of pregnancy (1) do not justify killing the baby and (2) are less significant than the risks of abortion. All this "terrible burden of pregnancy" stuff is a total exaggeration.
Adults need to be responsible for their actions. You can't just say, "He should have been responsible, not me!" or "It's not my fault, she could have said no!" Not when you then use that as the justification for killing an innocent human being conceived through your irresponsibility.
I'm using "your" in a generic sense here, not suggesting that either of you actually would do this :-).
Well, there are the very rare cases where death of the mother is a high possibility - that might be about the only time I'd support abortion. Self-defense.