I said a popular defence, not the only defence. Go to the abortiondebate or pro-choice subreddits and count how many people say that abortion is good on the basis of eliminating unwanted children.
Even better make a post asking if abortion is morally good (not just permissible, good) if the child would be born poor or the parents don’t want them. You will receive an overwhelmingly positive response, and you know it.