Behavioral development of premature infants: an ethological approach

This study examines the motor and social development of 21 very small preterm infants up to 34 weeks post-conceptional age. Seven infants were born at 26 to 27 weeks gestation, seven at 28 to 30 weeks and seven at 31 to 32 weeks. They were all physically healthy, as were their mothers. All the infants were observed for 40 minutes twice weekly, using a continuous recording technique. 12 types of infant behavior were recorded. The results indicate that the mean percentage and mean duration of both gross motor movements and 'social' behavior of these small infants do not vary between 26 and 34 weeks post-conceptional age. Moreover, infants born at 26 and 27 weeks gestation showed the same distribution of behaivor during their hospital stay as those born at 28 to 30 or 31 to 32 weeks. There was little individual stability over the weeks in the level of motor activity and social behaivor displayed by the infants, which implies that the behavior of these infants is generally variable as long as they remain physically healthy.