Abstract 1735

Infants born by caesarian section are at increased risk for developing respiratory morbidity. The underlying physiological mechanism for this has not been yet elucidated. The purpose of this study was to examine breathing patterns in infants delivered by caesarian section with and without a trial of labor.

Methods: The study group consisted of 8 infants who were delivered by elective caesarian section (5m/3f; GA:39±1 wk., BW: 3230±220 gr. with a mean Apgar score at 5 minutes of 8.7±0.7) They were compared to 8 matched infants (4m/4f; GA:39±0.7 wk., BW: 3530±210 gr. with a mean Apgar score of 8.5±0.5. NS) who had experienced a trial of labor with uterine contractions for at least three hours, but subsequently were delivered by caesarian section. None of the mothers or infants participating in the study, had any risk factors for respiratory problems. At age 40±4 hr. of life, a three hours polysomnographic study was performed. Periods of active and quite sleep, heart and respiratory rate, episodes of central and obstructive apnea were compared between groups.

Results: Infants in the study group had significantly higher heart rates (123±4 BPM vs. 113 ±8BPM p<0.007) and had more central apneas when compared to controls (2.4±0.1 vs. 1.9 ± 0.1; p<0.03). Apneic episodes were all self-limited and were not associated with arterial oxygen desaturation. There were no significant differences in respiratory rates between the groups. The ratio of active to quiet sleep was similar in the two groups.

We conclude that infants who were born by elective caesarian section have a different cardio-respiratory pattern, which may contribute to an increase risk for developing respiratory morbidity in the early postnatal period.