Newborn babies react to almost anything by crying.
There have been a number of good studies that show in fact that newborns and young children do, in fact, perceive pain and there may be long lasting effects to that. A topical cream called EMLA can be used to numb the skin before an injection. Lidocaine can be used for more painful procedures such as circumcision. There are many routine procedures such as injections and blood tests that can be anticipated and preventive measures could be taken. Doctors can often allow newborns to remain with their mothers and breastfeed or suck on a pacifier during routine blood tests.