This is one of those cases where it really depends not only on the circumstances in the individual case (eg if the woman is in danger, I think abortion is always justified). But it also depends on the society you live in. As gruesome as the 'spartan infanticide' option may seem, I have a lot of understanding that this happened, not just in Sparta but also here in Sweden where I live, before there were any safe methods for abortion. For me, the most important thing is that children are loved and cared for, and infanticide soon after birth is in my opinion a better option if that is not possible. Fortunately, we have better options today, both in that safe abortions are possible and, in our part of the world, readily available, and that once a child is born, it is never hard to find eager foster parents. It was not always so.
Because late abortions are not pleasant experiences, I think there is also a good argument to have a limit where the vast majority of women will have discovered their pregnancies and some time to consider their options, but the procedure is still not too invasive. It forces a decision on an issue where procrastination is otherwise likely to lead to bad consequences. So I'm fairly happy with the laws we have today here in Sweden, although I do not support the underlying principle that fetuses that can survive outside the womb can not be aborted. If, in the future, it becomes possible to grow a fertilized egg into a baby completely outside the womb, I would not support banning abortions.