I don't agree that a woman is a mom when pregnant. Caring for a child outside of the womb is much harder than being pregnant. That is why it's called mother to be not mother.
A woman becomes a mother the moment they found out they are pregnant a man becomes a father the day their child is born. They don't get to experience pregnancy as we do because they don't go through all the changes with their body and they don't get to feel the baby move inside of them therefore it usually dosent sink in until they actually see their child.
Some men are childish n haven't learned how to be a man yet. But then again some men just have a hard time dealing with the fact that they r having a kid but eventually come around to the fact. Only time will tell wat kind of man u r dealing with.they will never understand wat we r Goin thru no matter how hard we wish they wud . Sadly, I don't see how any man can walk away from his own flesh n blood but so many of them do. That's life :/