Injection For Baby

Our baby will be 6 months old next month. Just wondering for injection immunisation, which of this position is less painful when PD doctor administer the injection? Or same level of pain? 1) Lie down flat, turn sideways and PD administer the injection on Buttock. 2) We carry the baby, PD Administer the injection on Buttock. Is there also any ways we can help to relieve or lessen the pain before and after injection for Baby? Thanks.