Neonatal characteristics of the children born preterm (≤32 weeks gestation).

aNumber of skin-breaking procedures from birth to term, including each attempt (e.g. intubation, injection, line insertion, heel lance).bExposure to morphine (IV and PO combined after appropriate conversion) from birth to term was calculated as the average dose (mg/kg) per day adjusted for daily weight multiplied by the number of days on the drug.