The birth of a new brother or sister (or both!) is a major life event for a child. Some have even compared it to a 'life crisis', as the older child must now contend with not being the centre of their parents' world. Letting your child know about the pregnancy, deciding whether they will be at the birth and / or how you will 'introduce' the new baby, are universal issues.
How you decide to prepare your child for their new sibling can vary greatly, with people holding many different personal views on 'what is best'. Parenting our children is as individual as we are, so too is the way you will choose to prepare your older child, and whether you decide to include them in the actual birth or not. You can read about some thoughts and questions that frequently come up for parents having their second or subsequent baby. Some suggestions may guide you in how to approach preparing your child(ren) for the new baby.
The FAQ's of sibling preparation
Sibling rivalry, after the birth
Emotional considerations for the parents