Quantification of Nutritive Sucking Among Preterm and Full-term Infants

Purpose: We developed summaries of oral bottle-feeding skills among preterm (<37 gestational weeks) and full-term (≥37 gestational weeks) infants using a mechanical device (Orometer) to measure intraoral pressure changes, with accompanying automated software and analytics. We then compared the rates of change in feeding skills over several weeks (feeding trends) between preterm and full-term infants. We also compared group means at 40 weeks post menstrual age (PMA).

Patients And Methods: Healthy full-term and preterm infants capable of oral feeding were recruited from the Pediatric Outpatient Clinic at University of California San Francisco, Fresno, and from the Oregon Health & Science University Doernbecher Neonatal Critical Care Unit, respectively. Feeding skill was quantified using an Orometer and automated suck-analysis software. Factor analysis reduced the >40 metrics produced by the Orometer system to the following seven factors that accounted for >99% of the sample covariance: suck vigor, endurance, resting, irregularity, frequency, variability, and bursting. We proposed that these factors represent feeding skills and they served as the dependent variables in linear models estimating trends in feeding skills over time for full-term and preterm infants (maturation). At approximately 40 weeks PMA we compared mean feedings skills between infants born preterm and those born full-term using predictions from our models.

Results: Feeding skills for 117 full-term infants and 82 preterm infants were first captured at mean PMA of 42.3 and 36.0 weeks, respectively. For some feeding skills, preterm and full-term infants showed different trends over time. At 37-40 weeks PMA, preterm infants took approximately 15% fewer sucks than infants born full-term (p=0.06) and generally had weaker suck vigor, greater resting, and less endurance than full-term babies. Preterm infant-feeding skills appeared similar to those of full-term infants upon reaching ≥40 weeks PMA, although preterm infants showed greater variability for all factors.

Conclusion: The Orometer device, accompanying software, and analytic methods provided a framework for describing trends in oral feeding, thereby allowing us to characterize differences in maturation of feeding between healthy preterm and full-term infants.