Our objective was to evaluate maturation of sucking and swallowing in preterm infants using a non-invasive method: assessment of swallowing sounds. Findings in healthy term infants were used as reference values.

Successful transition to full oral feeding in preterm infants is important for safe discharge from hospital and for facilitating the mother-infant bond. Preterm infants were evaluated weekly for sucking and swallowing performance (i.e., feeding performance) from the time they began oral feeding (frequency 1-2 oral feedings/day) until they reached independent oral feeding (frequency 8 oral feedings/day) at postmenstrual 38-40 weeks. For the term infants, we evaluated a single oral feeding during the first week of life.

The exclusion criteria were major congenital abnormalities, craniofacial malformation, intracranial hemorrhage, bronchopulmonary dysplasia, culture-positive sepsis, and necrotizing enterocolitis. Each swallowing-sound recording was 2 minutes long and was captured in a quiet environment by the same investigator. The feeding parameters generated from the recordings were as follows: total number of swallows (S), total number of rhythmic swallows (RS), total number of resting intervals (RI), average time between resting intervals (ATRI), average time between swallows (ATS), average time between rhythmic swallows (ATRS), maximum number of rythymic swallows (MRS), and volume of milk ingested (VM) during the 2-minute evaluation.

Inclusion Criteria:

• Preterm infants (< 37 gestational weeks) and term infants (>=37 gestational weeks)

Exclusion Criteria:

- The exclusion criteria were major congenital abnormalities, craniofacial malformation, intracranial hemorrhage, bronchopulmonary dysplasia, culture-positive sepsis, and necrotizing enterocolitis.

Preterm infants (< 37 gestational weeks) and term infants (>=37 gestational weeks)