Characterization of the developmental stages of sucking in preterm infants during bottle feeding.

It is acknowledged that the difficulty many preterm infants have in feeding orally results from their immature sucking skills. However, little is known regarding the development of sucking in these infants. The aim of this study was to demonstrate that the bottle-feeding performance of preterm infants is positively correlated with the developmental stage of their sucking. Infants' oral-motor skills were followed longitudinally using a special nipple/bottle system which monitored the suction and expression/compression component of sucking. The maturational process was rated into five primary stages based on the presence/absence of suction and the rhythmicity of the two components of sucking, suction and expression/compression. This five-point scale was used to characterize the developmental stage of sucking of each infant. Outcomes of feeding performance consisted of overall transfer (percent total volume transferred/volume to be taken) and rate of transfer (ml/min). Assessments were conducted when infants were taking 1-2, 3-5 and 6-8 oral feedings per day. Significant positive correlations were observed between the five stages of sucking and postmenstrual age, the defined feeding outcomes, and the number of daily oral feedings. Overall transfer and rate of transfer were enhanced when infants reached the more mature stages of sucking. We have demonstrated that oral feeding performance improves as infants' sucking skills mature. In addition, we propose that the present five-point sucking scale may be used to assess the developmental stages of sucking of preterm infants. Such knowledge would facilitate the management of oral feeding in these infants.