Abstract
Understanding of infant pain has been transformed in the past 30 years. From assumptions that newborns were insensitive to pain, fundamental work established not only the infants perceive pain, but also there are critical windows in which pain can have long-lasting consequences. My multidisciplinary work revealed that repetitive pain exposure during the late 2nd and 3rd trimesters of fetal life "ex-utero" in infants born very preterm is related to long-term adverse associations with altered brain development, programming of stress systems, and thereby neurodevelopment. Here, influences will be described, discovery research summarized, and evidence of biological pathways proposed.