Early vocalization of preterm infants with extremely low birth weight (ELBW), Part I: From birth to expansion stage.

The vocalization of preterm infants with extremely low birth weight (ELBW) up to the expansion stage was systematically described and compared with those of healthy full-term infants. The sample consisted of 18 preterm ELBW infants and the control group of 11 full-term infants. The follow-up was performed intensively using video-recordings. The vocalization of the preterm and full-term infants was analyzed quantitatively according to the categorical stages created by Oller. A descriptive analysis of all the vocalizations produced by the infants was performed. The preterm infants entered the primitive articulation stage later than the full-term infants and failed to produce more skills during that stage. According to this sample, there was no difference in entering the expansion stage, but the preterm infants failed to produce more skills than the full-term infants. The number of vocalization acts varied differently by age between the groups.