ObjectiveTo characterize cardiorespiratory events in preterm infants following both acid and non-acid GER as detected by pH and multiple intraluminal impedance (MII).Study DesignTwelve hour overnight studies were performed in 71 preterm infants (gestational age 29.4±3.0 wks, birth weight 1319±496 gm). Apnea ≥10 seconds in duration, bradycardia ≤80 bpm and oxygen desaturation ≤85% that occurred within 30 seconds after the initiation of GER were classified as associated with GER.Result12,957 cardiorespiratory events and 4164 GER episodes were documented. Less than 3% of all cardiorespiratory events were preceded by GER constituting 3.4% of apnea, 2.8% of oxygen desaturation and 2.9% of bradycardia events. GER did not prolong cardiorespiratory event duration or increase severity. In contrast, GER was associated with a shorter duration of oxygen desaturation events (7.8±4.6 vs 6.3±5.6 sec, p<.05).ConclusionGER is rarely associated with cardiorespiratory events, and has no detrimental effect on cardiorespiratory event duration or severity.