An analysis of data from the multicenter (25 centers) Canadian Oxygen Trial of over 1000 infants 23 to 27 weeks gestation looked at the association between episodes of hypoxemia (oxygen saturation <80%) or bradycardia (pulse rate <80/min) for 10 seconds or longer, and late death or disability. Hypoxemia occurred for a mean of 0.4 to 14% of the monitored time, and bradycardia from 0.1 – 0.3% of the time. Infants in the highest decile of hypoxemic exposure had an increased risk of late death or disability at 18 months compared to those in the lowest decile (57% vs 37%). This association was significant only for prolonged hypoxemic episodes lasting at least 1 minute. Bradycardia did not alter the prognostic value of hypoxemia.