hey thanks
I've been there twice.
Women (understandably) are irritable at this time.
Listen to what others are saying here though, it's not just about you now, you have your girlfriend and the baby to look after.
You have to think how your actions will come across to a hormonal/tired woman, I can see where she might be coming from if you are still thinking about 'me' all the time and how tired 'you' are all the time, your negative actions are going to be amplified in situations like this.
Just phone her when you can, talk rationally, apologise if needed. Be a man and don't go down the route of you this, you that. It's give and take now there is a baby involved.