To determine whether targeting lower arterial oxygen saturations from the day of birth alters the early (first 3 months) postnatal development of the control of ventilation and the hypercapnic and hyperoxic responses in very preterm infants.

To measure the effects of baseline oxygenation in extremely low birth weight preterm infants on:

i) The early (first 5 breaths) and late or steady state (3-5 minutes) ventilatory response to CO2 ii) The immediate (< 1 minute) ventilatory response to hyperoxia iii) The PCO2 apneic threshold iv) The breathing pattern during quiet and REM sleep v) The morphology of periodic breathing cycles vi) The incidence and morphology of sighs

Inclusion Criteria:

• Gestational age 23 0/7 - 27 6/7 weeks
• Enrolled in the COT trial at the Health Sciences Centre and the St. Boniface General Hospital in Winnipeg
• Postnatal age between 21 days and 70 days
• Informed written consent obtained from at least one of the parents.

Exclusion Criteria:

• Need for mechanical ventilation, NCPAP or O2
• Sepsis or other known causes of apnea.