Recent research has begun to examine discrete caregiver pain management behaviors in the infant immunization context. However, there is a dearth of research exploring more global caregiving constructs, such as emotional availability, which can be used to examine the overall sensitivity of caregiver pain management. The aim of the present study was to examine the relationships between caregiver sensitivity (emotional availability) and infant pain behavior (baseline, immediately post-needle, 1 min after needle) over the first year of life. Parents and infants were a part of a Canadian longitudinal cohort (the Opportunities to Understand Childhood Hurt or OUCH cohort) followed up during their 2-, 4-, 6-, and 12-month immunizations (current n=731). Both within-age group analyses and over-age analyses were performed. Results indicated that: (1) over age, previous infant pain behavior predicts future infant pain behavior, but this varied depending on timing of pain response and age of infant; (2) over age, previous caregiver sensitivity strongly predicts future caregiver sensitivity; and (3) the concurrent relationship between caregiver sensitivity and every type of infant pain response is only consistently seen at the 12-month immunization. Caregiver sensitivity to the infant in pain is predicted most reliably from previous caregiver sensitivity, not infant pain behaviour. The significant concurrent relationship between caregiver sensitivity and infant pain behaviours is not seen until 12 months, replicating patterns in the infant development literature regarding the time at which the attachment relationship between parent and child can be reliably measured. Discussion addresses implications for both researchers and clinicians who work with infants in pain.

No research to date has descriptively catalogued what parents of healthy infants are naturalistically doing to manage their infant's pain over immunization appointments during the first year of life. This knowledge, in conjunction with an understanding of the relationships different parental techniques have with infant pain-related distress, would be useful when attempting to target parental pain management strategies in the infant immunization context. This study presents descriptive information about the pain management techniques parents have chosen and examines the relationships these naturalistic techniques have with infant pain-related distress during the first year of life. A total of 760 parent-infant dyads were recruited from 3 pediatric clinics in Toronto, ON, Canada, and were naturalistically followed and videotaped longitudinally over 4 immunization appointments during the infant's first year of life. Infants were full-term, healthy babies. Videotapes were subsequently coded for infant pain-related distress behaviors and parental pain management techniques. After controlling for preceding infant pain-related distress levels, parent pain management techniques accounted for, at most, 13% of the variance in infant pain-related distress scores. Across all age groups, physical comfort, rocking, and verbal reassurance were the most commonly used nonpharmacological pain management techniques. Pacifying and distraction appeared to be most promising in reducing needle-related distress in our sample of healthy infants. Parents in this sample seldom used pharmacological pain management techniques. Given the psychological and physical repercussions involved with unmanaged repetitive acute pain and the paucity of work in healthy infants, this paper highlights key areas for improving parental pain management in primary care.

Given the inherent variability in pain responding, using an "average" pain score may pose serious threats to internal and external validity. Using growth mixture modeling (GMM), this article first examines whether infants can be differentiated into stable groups based on their pain response patterns over a 2-minute post-needle period. Secondary analyses, to specifically address the issue of averaging pain scores to represent a sample, qualitatively described clinically meaningful differences between pain scores of the discerned groups and the overall mean (irrespective of groups). Infants were part of Canadian longitudinal cohort naturalistically observed during their 2-, 4-, 6-, and/or 12-month immunization appointments (N=458 to 574) at 3 pediatrician clinics between 2007 and 2012. At every age, GMM analyses discerned distinct groups of infants with significantly variable patterns of pain responding over the 2minutes post-needle. Our secondary suggested that the overall mean pain score immediately post-needle reflected most groups well at every age. However, for older infants (6 and 12months, especially), the overall mean pain responses at 1 and 2minutes post-needle significantly over or underestimated groups that contained 48% to 100% of the sample. These results combined highlight the significant variability of infant pain responding patterns between groups of infants and furthermore, calls into question the validity of using an overall mean in research with older infants during the regulatory phase post-needle.