People often say they'll work it out when the time comes. But when the time does come, there are so many other emotions at play, along with the added stress of sleep deprivation, that tempers flare and resentment builds. If you can get this under control, or have back-up plans before the baby is born, you'll be ahead of the game. Relationships with in-laws should also be discussed before the new grandchild is here. If there are problems with getting along with in-laws, now is the time for the couple to talk about how often they will visit grandparents and other important issues.
Money is a hot topic, too.
At least temporarily, one income will be lost. It will be much easier if you devise a budget now. Also talk about how the woman will feel when she is not bringing home a paycheck and how you can avoid power struggles about money. Getting problem areas ironed out before the baby is born will help you avoid trouble later. Get counseling if necessary before the birth of your baby.