Fill your child in on the arrangements you've made for when you go the hospital, shortly before your due date. Tell him who will care for him and that you'll be home in a few days. If possible, have your toddler come to meet the new baby at the hospital.
Most parents find that there's an initial "honeymoon" period when a younger sibling comes home from the hospital. A toddler may initially shower the new baby with hugs and kisses, giving rise to a rosy parental vision of the two as lifelong pals. This state of bliss usually passes, however. Signs of jealousy, such as aggression toward the baby -- or the parent! -- may surface, and some toddlers have a tendency to regress temporarily to more babyish behaviors.
You can help minimize the negative feelings that are bound to arise by focusing as much attention as possible on your older child. Hire a babysitter so that you and your toddler can participate in a weekly activity together, and make room in your schedule for her to do something special, one-on-one, with Dad.
Make your child feel like more of a participant by having her help, in small ways, with the baby's care and feeding. For example, she can bring you a clean diaper, help pat the baby's back at burping time, and stand by during the bath to hand you the soap and towel.
Don't scold your child for expressing negative feelings about his new sibling. Reassure him that you know it can be hard to have a new baby in the house, and perhaps recount a time in your own childhood when a new brother or sister came along.
If your toddler truly tries to hurt the baby, deal with the behavior quickly and firmly. Be alert. Sometimes such aggression will be slyly subtle, such as the toddler's "holding" his baby sister's hand in a pythonlike grip.
Even if you don't sense much animosity toward the new sibling, a word of caution is in order: Never leave the baby unattended with your 2-year-old. Overt aggression isn't the only fearsome possibility. The toddler still views the world as a giant laboratory ripe for experimentation, and a "test" on a baby sister ("I wonder what would happen if I pinched her...") can have serious consequences.