Children should not sleep with their parents on a nightly basis. It is understandable to have a child sleep with, or near, you if they are ill. Allowing your child to sleep with you every night can have several adverse effects.
The first thing to think of is your child's safety. One harmful effect can be smothering or suffocating. There is a chance you could roll over on your baby unknowingly. The baby could also get injured if they were to fall off the bed.
Parents let their children sleep with them for reasons of security. The child feels safe and secure in Mommy and Daddy's bed, and after several nights of sleeping with Mommy and Daddy he will become reluctant to sleep in his own bed.
Sleeping with Mommy and Daddy will become a habit for the child. They will become upset when told they can't sleep in their parents' bed. The only way to get the child comfortable with their own bed again is to resist giving in to protests. Take the child to their room, tuck them in and in a few nights they will break the habit of sleeping with Mommy and Daddy.