I hate it when people say "having kids is a choice" as an excuse for denying parents things like maternity leave, etc. For several reasons:
1) Having kids is not always a choice. Many people use birth control properly and still get pregnant. People get raped.
2) If you expect someone else to abort a fetus so you don't have to work a little harder, then you are a bad person. I don't care where you lie on the abortion debate, that definitely makes you a bad person.
3) We don't refuse to provide food to destitute children just because their parents made a choice by having them. Forcing a parent to do something that is detrimental to the child just because a choice was made to have them is not ethical.
4) Having kids is as much of a choice as eating. You don't have to eat. You could stop entirely if you wanted. Of course, you'd eventually die. But that's what would happen to the human race if everyone made the "choice" to stop having kids. Anything that is almost solely responsible for preserving the species is not a choice. Some people feel that compulsion more than others, but it's quite powerful, especially in many (not all) women.
There are few things more natural than having sex and procreating. Every species, every race has done it since the beginning of time (unless you're an amoeba). It's an essential component to most romantic relationships. And if you try to use the "sex is a choice" argument, all I think is that you're not getting any at home, sorry.
I should also mention my husband's argument, which is that doctors who say that are a bunch of snobs who think that what we're doing is so important that we're on some higher level of humanity that ought to be exempt from basic human functions like procreation.