Respiratory pauses in very low risk prematurely born infants reaching normal term. A comparison to full-term newborns.

We studied the occurrence of greater than or equal to 2 sec. respiratory pauses (RP) in very low risk, normal prematurely born infants (less than or equal to 36 wks. of gestation), recorded when they reached 37-40 wks. conceptional age and compared the results with those of full-term (37-41 wks. of gestation) newborns. The influence of gestational age at birth (GA), postnatal age, sleep states, twin birth and gross body movements was tested. We recorded 2434 central RP and only one 4 sec. duration obstructive RP. We never observed RP greater than 15 sec. 10-15 sec. RP were rare, noted only in 37-38 wks. GA newborns. We found some differences between prematures reaching normal term on one hand and full-term newborns on the other: a) RP frequency and periodic breathing were higher in prematurely born infants; b) Between-sleep state differences leveled out in prematures reaching normal term (they had more numerous RP in all sleep states), while the prevalence of RP in active sleep compared to quiet sleep was constant in full-term newborns. There were no significant differences between prematurely born twins and singletons. When they reached normal term, infants born before 35 wks. of gestation had more RP, compared to infants born at 35-36 wks. of gestation. About 12% of RP occurred after gross body movements.