Pain, 52 (1993) 287-299 0 1993 Elsevier Science Publishers B.V. All rights reserved 03~-3959/93/$~.00 287 PAIN 02221 Research Reports Pain in the preterm neonate: behavioural and physiological indices Kenneth D. Craig a, Michael F. Whitfield ‘*lr,Ruth V.E. Grunau a,b, Julie Linton b and Heather D. Hadjistavropoulos a a University of British &olumbia and bBritish Columbia Children’s Hospital, Vancouver, B.C. V6T IZ4 (Canada) (Received 1 May 1992, revision received 4 September 1992, accepted 18 September 1992) zyxwvutsrqponmlkjihgfedcbaZ Summa~ The impact of invasive procedures on preterm neonates has received little systematic attention. We examined facial activity, body movements, and physiological measures in 56 preterm and full-term newborns in response to heel lancing, along with comparison preparatory and recovery intervals. The measures were recorded in special care and full-term nurseries during routine blood sampling. Data analyses indicated that in all measurement categories reactions of greatest magnitude were to the lancing procedure. Neonates with gestational ages as short as 25-27 weeks displayed physiological res~nsivi~ to the heel lance, but only in the heart rate measure did this vary with gestational age. Bodily activity was diminished in preterm neonates in general, relative to full-term newborns. Facial activity increased with the gestational age of the infant. Specificity of the response to the heel fance was greatest on the facial activity measure. Identification of pain requires attention to gestational age in the preterm neonate. Key words: Neonate; Facial activity; Heel lance; Preterm; Behavioral obse~ation; Physiological measures Introduction The healthy, fulf-term newborn emerges from the protective intra-uterine environment well-equipped bi- ologically to experience pain (Anand and Hickey 1987; Anand and Carr 1989) and displays acute painful dis- tress when tissue damage occurs (Johnston and Strada 1986; Fitzgerald 1991; Craig and Grunau in press). In contrast, investigations of the preterm neonate’s re- sponse to tissue insult have been less definitive, and detailed descriptions of the behavioural response have not been undertaken. The development of assessment instruments sensitive and specific to pain is essential, for the control of pain in premature newborns cannot be undertaken without them. In the absence of valid measures many questions concerning optimal clinical care remain open (Anand and Hickey 1987; Pigeon et al. 1989; Fields 1990; Schuster and Lenard 1990; Barr 1992). Correspondence to: Kenneth D. Craig, Department of Psychology, 2136 West Mall, University of British Columbia, Vancouver, B.C. V6T 124, Canada. The population of infants born too early is of special concern because they often must be subjected to painfuf medical procedures; yet they are fragile, vulnerable to physiological shock, and particularly dependent upon adults to assess their needs accurately. Survival of very small infants and those born as early as 25 weeks post-conCeptua1 age is now considerable (Terdal 1990). It is noteworthy that Shapiro (1991) found nurses to judge premature neonates to be suffering less than full-term newborns even though both groups had un- dergone the same noxious procedure. In contrast, stud- ies of cutaneous, flexor, reflexive movements in the preterm responding to noxious stimuli (e.g., Fitzgerald et al. 1989) led Fitzgerald and McIntosh (1989) to the conclusion that “the preterm infant is, if anything, supersensitive to painful stimuli when compared with the full-term infant” (p. 442). Shapiro (1991) effectively states the case for the development of measures as follows, “Lack of recognition of pain in premature neonates may result in unnecessary suffering, increased morbidity and mortality for this vulnerable group” (p. 148). Assessing the presence and severity of pain in the newborn is difficult because pain is a subjective phe-