When a new baby is born, other babies may be excited. But they will have to learn to share love and attention with the newborn. This can be a big step, especially if the kids are still toddlers. They may feel like they are being pushed out of the spotlight.
Almost all children need to adjust when a new child arrives in the family. But good sibling relationships eventually develop—usually by the time the newborn is about 14 months old. If you are preparing for the birth of a child, then when and how much you tell your child about the new baby is up to you. The age of your child will also play a role.
It would be good to introduce the idea of a new baby early in pregnancy, perhaps 3-4 months before the baby is born. You can try talking about children in general and then talking about your new baby. Toddlers don’t really understand time, so when you explain to a child that a new baby is coming, try to associate it with a familiar event. For example, you might say that a new baby will be born shortly after a special person’s birthday.