I really think that something like this might be better, caranfin:
Before you ask someone if they plan to have children, keep in mind that this topic is usually none of your business, and that it can be an annoying or painful question for people who don't want or can't have children. Don't ask if you're just making conversation. If you feel that you have a valid reason for asking this question, figure out a way to work it into the conversation, or just have faith that they will come to you if they need advice on the subject.