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Background: Non-nutritive sucking (NNS) by the newborn infant is a fundamental behaviour and is one of the first coordinated muscular activities in the fetus., Aims: Our objective is to study the NNS pattern in prematurely born infants, who had various conditions commonly associated with immaturity., Method: A specially designed computer-based method that analyses and quantifies components of the NNS pattern was used., Subjects: The pattern of 51 clinically stable prematurely born infants (gestational ages 26-35 weeks) making a total of 206 observations were analysed and findings were compared with those obtained from 58, healthy preterm infants., Results: The rhythmic NNS pattern of alternating sucking and pauses was elicited in all examined infants, the earliest at post-menstrual age (PMA) 26 weeks. The role of PMA, the dominant predictor for several sucking variables seen in the control group, became diminished for the infants with risk factors but changes were otherwise similar. The infants' sucking activity and sucking frequency increased and the variability of the pattern declined with increased PMA and weight. Follow-up of a subgroup of infants revealed fewer sucking bursts per minute, slower sucking frequency and a greater variability of the frequency and amplitudes in those infants who developed sequelae., Conclusions: It would, thus, appear that the NNS pre-programmed rhythm generator, primarily modulated by maturation in healthy preterm infants, becomes affected by known risk associated events and in infants who later develop sequelae. Quantification of the NNS pattern in preterm infants may be a valuable future component of their evaluation.

In the infant, sucking behaviour is one of the first coordinated muscular activities. It is under the control of the brainstem. In utero sucking is observed from 13 weeks' gestation. The healthy full-term newborn infant has a very stable rhythm of alternating bursts of sucking with pauses in between. The non-nutritive sucking (NNS) patterns of 58 low-risk prematurely born infants (gestational ages between 26 and 35 weeks) were studied using a specially designed computer-based method that analyses and quantifies NNS. A total of 183 observations were analysed. The typical NNS pattern with bursts of sucking activity separated by quiescent periods was recorded in all infants studied and was already present before 30 weeks of gestation. A gradual change over time of their NNS was seen. With increased maturation the sucking activity, sucking frequency, amplitude and burst duration all increased, while the variability of the sucking frequency and the duration of the intervals between bursts declined. Post-menstrual age (PMA) was the dominant predictor of this result but gender, state of activity and weight also influenced it to some extent. Girls had more sucking activity and a higher sucking frequency than boys. State of activity affected the stability of the rhythm. The weight of the infant influenced both sucking activity and duration of separate bursts.