Respiratory development in preterm infants.

Objective: This study examined the development of respiration during the preterm and early post-term periods and the effects of other biological and environmental variables, including sleep state, on this development.

Study Design: Weekly 2-hour sleep observations and respiration recordings were obtained on 134 preterm infants from the time they were no longer critical until hospital discharge; a follow-up observation was conducted 1 to 3 months later.

Results: All respiratory variables, except length of respiratory pauses in quiet sleep, decreased although the rate of this decrease slowed after term for four variables. Respiratory variables, except variability of respiratory pauses lengths and periodic respiration, differed by sleep state. Covariates, except methylxanthine treatment, had minor effects. Four variables showed hospital-related differences, but cisapride treatment helped to explain the differences in three variables.

Conclusions: Much development of respiration occurs in the early weeks after birth and reflects both neural maturation and effects of other biological and environmental factors, especially medications.