Does neonatal circumcision alter behavioral pain response during subsequent routine immunizations?

Pain experienced during infancy may have long-term effects on future pain response. Study objectives were to determine whether neonatal circumcision altered behavioral pain response during subsequent immunizations compared to uncircumcised infants and whether pretreatment of circumcision pain affected subsequent immunization response. Using data from our previously reported randomized clinical trial, 97 male infants presented for immunizations at 4 and 6-months of age, 82 were circumcised. Seventy-five infants received analgesia prior to circumcision; seven infants did not receive preemptive analgesia. The University of Wisconsin's Children's Hospital pain scale measured acute pain response at baseline, 2 and 5 minutes. Independent T-tests examined the effects of circumcision vs non-circumcision and circumcision with or without preemptive analgesia on overall pain scores. There were no significant differences in pain response at 2 and 5 minutes, at 4 and 6-months of age, by circumcision status. At 4-months, mean pain response was 5.00 vs 4.90 (P=.464) at 2 minutes and 0.80 vs 1.02 (P=.637) at 5 minutes for uncircumcised vs circumcised infants respectively. At 6-months, mean pain response was 4.80 vs 4.87 (P=.679) at 2 minutes and 0.80 vs 0.80 (P=.999) at 5 minutes respectively. Among circumcised infants, preoperative treatment with lidocaine did not attenuate pain response at 4 and 6-months of age. At 4-months, mean pain response was 5.00 vs 4.89 (P=.601) at 2 minutes and 1.44 vs 1.01 (P=.847) at 5 minutes for non-analgesic vs analgesic infants respectively. At 6-months, mean pain response was 4.71 vs 4.89 (P=.440) at 2 minutes, and 1.14 vs 0.76 (P=.522) at 5 minutes respectively. Findings suggest preemptive analgesia during circumcision does not attenuate pain response during immunizations at 4 and 6-months of age.