Infants treated with prenatal betamethasone (B) had fewer abnormalities on pneumocardiograms(PCG) during the first week of life and at discharge.

Twenty four infants (BW 1695 +/- 301g; GA 32.0 +/- 1.3wks) receiving 2.5+/- 2.2 courses of B were compared to five untreated infants (BW 1838 +/- 191g; GA 33.2 +/00.2 wks) using continuous documented monitors during the first week and 12 hour PCGs at discharge. The groups were comparable except for gestational age; treated infants were significantly younger. Both monitors recorded apnea, bradycardia, and oxygen saturation, while the PCG also documented periodic breathing. Pathologic apneas (PA) were defined as central apneas > 20 seconds or < 20 seconds but associated with bradycardia < 100 bpm or desaturations < 90%.

During the first week of life the B group experienced 3.3 +/- 4.2 PA events compared to 6.0 +/- 5.0 in the untreated group (p>0.05). At discharge (18.0+/- 7.9 days in treated vs. 14.6 +/- 3.2 days in untreated infants), periodic breathing was 1.5 +/- 1.9% vs. 7.6 +/- 2.4% (p<0.05), PA 1.3 +/- 1.5 vs. 1.0 +/- 1.4 episodes, and bradycardia 1.3 +/- 1.1 vs. 3 +/- 1.4 episodes(p=0.07) in B versus untreated infants. Negative correlations were noted between number of B courses and periodic breathing (r=-.32), PA (r=-.16) and bradycardia (r=-.50).

Since birth weight is an important confounder of respiratory control, it is important to note that the younger B infants had less abnormal events, suggesting that B may have a maturational effect on the control of respiration.