There was a study or two that did this. Interestingly, the Lander anesthesia study was stopped when the researchers noticed that the newborn's cortisol levels during their circumcisions indicated that they were putting the child in great pain and at risk for stroke. Therefore, we can take from this that it is unethical to use infants as test subjects in pain studies. I suggest you find another solution, perhaps using sucrose as pain relief for adult procedures since the adults can legally consent and tell you when they are in too much pain.
Lander J, Brady-Fryer B, Metcalfe JB, Nazarali S, Muttitt S. Comparison of ring block, dorsal penile nerve block, and topical anesthesia for neonatal circumcision. JAMA. 1997;278:2158-62.