Newborn temperament and Sudden Infant Death Syndrome: A comparison of victims and their cotwins

Temperament assessed in the newborn period was compared for four twin infants who subsequently died of Sudden Infant Death Syndrome (SIDS) and their surviving cotwins. The assessment focused on irritability, resistance to soothing, reactivity, reinforcement value, activity while awake, and activity during sleep. No differences were observed between cotwins on a combined irritability rating. SIDS victims, however, were less irritable than their siblings in response to aversive stimuli. When irritable, the SIDS infants were more difficult to soothe than their cotwins. While awake, SIDS infants were less active than their cotwins, but during sleep, no activity differences were observed. The SIDS infants were more reactive to orienting stimuli, and neither group was found to be more or less rewarding to the examiner. It was concluded that this study has helped to define behavioral variables that might be characteristic of infants whose subsequent deaths are attributed to SIDS.