There is a better option that allows you to have as many children as you want whenever you want: adoption. Why bring in more children into the world when there are already so many that are unwanted?
As population growth stabilizes in the developing world, and contraception and abortion become more widespread, adoption is going to become even less of a practical alternative to having ones' own children.
In any case, adopting an older child is a huge undertaking and not something someone should do just because she wants a child. These kids often already manifest issues resulting from parents who are drug users, etc. They need much more support than your typical child.