At Mount Sinai Medical Center, in New York City, four preschoolers and their expectant moms sit in a circle. The kids are cuddling newborn-size dolls as nurse Betina Grigoroff-Aponte leads a discussion.

"Why is Mommy going to be in the hospital when she has your little brother or sister?" she asks.

"Because she's going to have to work harder than climbing a mountain to get him here," says 5-year-old Andrew Older of Edgemont, NY.

Welcome to Sibling Prep 101, where kids learn about some ways their families will change when the new addition arrives. "Talking about what's going to happen when the baby's born  -- and actually showing kids where Mommy will be when it happens  -- helps them adjust," says Grigoroff-Aponte.

Hospitals around the country offer these workshops, usually led by nurses, and they're well worth signing up for (expect to pay a minimal fee). If your hospital doesn't offer one, here are some tips from Grigoroff-Aponte:

Show your child his own baby pictures

(both before and after his new sibling is born) and tell him how he acted when he was small. You can say that he cried a lot because he couldn't talk, and Mommy and Daddy had to pay a lot of attention to him. Emphasize that though the baby will take up a lot of your time, she'll eventually be a big kid just like her brother.

Appoint your child the baby's protector.

Explain that it's his job to make sure that people are very gentle with the baby's fingers and toes. He'll feel important and get the basics of newborn safety.

When you bring the baby home,

have someone else carry her into the house and keep your arms available for a big hug. Or arrange for your older child to be away when you first get there so when he comes in, you're settled and ready for him.

Invite him to have a snack when you feed the baby,

and let him hold a book up for you to read to him. Store a small stash of treats and books in a spot he can reach.