What is the purpose of the injection given to the baby at birth and is it really important for him to receive it?

I believe you are referring to the injection of vitamin K to prevent Hemorrhagic Disease of the Newborn. Other injections might be necessary at delivery depending on a host of factors, but vitamin K is given routinely as the newborn has a very low reserve of the vitamin, which exposes him or her to a high risk of severe bleeding (hemorrhage) that could endanger his or her health. The injection is given intramuscularly as it is more comfortable for the child than most other types of injection and as the oral route is much less efficient for absorption of vitamin K. Pain and complications are exceedingly rare when given by a competent nurse. Pain and complications are exceedingly rare when the injection is given by a competent nurse. If it is still possible to refuse the injection, it is not without risk and most major bleeding can be prevented with this injection. A pre-delivery discussion with the doctor is essential to make an informed decision and to be able to detect problems should you decide to refuse the injection anyway.