will pregnancy delay finalization of divorce is not the husband's child

I practice in NY, but generally if a child is born while the mother is married to a man, there is a presumption in the law that the child is his. That presumption can be rebutted by using a DNA test to determine if it truly is his. If not, he is not responsible for support. If so, then he's responsible.

Generally, pregnancy has little to do with the divorce, however, there may be child support considerations that should be resolved first and paternity should be resolved first, so that may hold up the divorce. Most courts don't want any loose ends when a divorce is being finalized, so if someone is pregnant, unless the true father is disclosed beforehand, the court may insist upon a DNA test before granting the divorce.