It's definitely best to have a plan in place for who'll be looking after your kids when you head in to deliver. Try to make arrangements for a grandparent or trusted friend to be on call for your impending labor. If you don't have family nearby or friends that are available, consider looking into a sitter with a flexible schedule. (It's a good idea to have the sitter come in a few weeks before delivery to meet the kids — everyone needs time to get used to each other.)
When the contractions start coming, plan to give your designated caregiver a ring. They can take over until your back in action. Don't forget to check your hospital's policy to see whether young siblings are allowed to visit after the birth. It's also smart to have a backup plan for who (family member? Neighbor? Sitter?) will be in charge of caring for your older kids in case you end up staying in the hospital longer than expected.
If you must bring the kids along, some hospitals do allow siblings in the delivery room. However, you'll still need to have a caregiver present who is solely responsible for tending to your older children. You also should do some serious prep to ensure your little one is ready to see Mommy in such pain (sorry).