I agree with the comments made previously, having children is not an issue on which one should compromise. If the decision was about when to have children, then a compromise could be reached. Even that has to be discussed in depth. One person's idea of soon could be 15 years, while the other party is thinking more along the lines of 15 months.
Also things such are you against children in general, solely against going through childbirth, willing to adopt, etc..
This is one of those topics that lead to divorces further along the road so anyone considering marriage and even intimate relationships in general need to talk about it. You never know what could happen. What if the lady ends up pregnant and the partner does not want kids, what does he expect her to do??