Contrary to common assumption, data on the incidence and resolution of apnea at different gestational ages (GA) is lacking. Our hypothesis was that the incidence of apnea and the GA at which apnea resolves is inversely related to the GA at birth. We reviewed the neonatal data on all infants (n=1753) admitted to a tertiary referral NICU from 7/1/93 to 6/30/97. Incidence of apnea, stratified by GA was determined in 1152 infants (115 died, 486 transferred). For the resolution of apnea, we analyzed data for the 437 surviving infants with apnea who were discharged home directly from our nursery, using corrected gestational age (CGA) in weeks at the last apnea. Table

Table 1 No caption available.
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Results: The incidence of apnea was 81% in infants ≤ 33 wk GA and 10.3% in infants ≥ 34 wk GA. In preterm infants, the GA at which apnea resolves is related to the GA at birth (R2 =0.12, p< 0.0001). While apnea lasts until a mean CGA of 30.9 wk in infants ≤ 26 wk GA at birth, it lasts until a mean CGA of 33.9 wk in infants of 27-33 wk GA at birth (unpaired t-test, p<0.0001). Conclusion: Although infants of a GA ≤ 26 wk at birth have a higher incidence of apnea, they actually cease having apnea at an earlier CGA suggesting an enhanced maturation of the respiratory control centers in these infants ex-utero. The variable age at resolution of apnea in infants ≥ 34 wk GA may reflect the varied etiology of apnea in the more mature infants.