The most important thing is to show consideration for your partner, the expectant mother, who will be feeling unsettled, both physically and mentally.
Do not simply accept that housework won't get done; take a positive role and help out around the house.
While you may be busy, try to remember that the most important thing right now is to cooperate and provide encouragement for the mother-to-be so she can give birth to a healthy new baby. If you smoke, avoid smoking in the same room. A supportive father is the single most important source of happiness for an expectant mother.