This is like a flood of extra rainwater causing the banks of the river to spill over. Spilling over occurs when you just have too much to deal with. This can be at work, at home, with the baby, or anything. In these situations, arguing becomes a safety valve that lets off pressure. It helps to develop other ways of releasing tension.
Some people exercise.
Other people cook, go shopping, call friends, pray or meditate, or take a long, soaking bath. It is important to find a healthy alternative or spillover will occur again, just at a later date. When your relationship is changing because of parenthood, try to get a bird's eye view and get away from the details. Remember that sometime down the road, your children will be grown, launched on their own journey through life. You and your spouse will still be together.