Babies are expensive! There are initial expenses such as clothes, crib, car safety seat, and stroller, continuing costs such as diapers and food, medical costs, and child care if you work outside the home.
As with everything else in parenting, things generally go much better if you prepare ahead of time. If you can, use the time before you have the baby to save money, to pay off debts, and to get your finances in better shape.
If you decide to stay home and you have been a two-income family, switching to one income is sometimes challenging. You will need to adjust your household budget and resolve any conflicts that less money may create. You may want to schedule regular times when you and your spouse can review the family's finances and decide what to do.