Due to the medial fragility of these infants it was planned that participation would be discontinued if any one of the following infant distress symptoms occurred: irregular respiration or apnea, flushing or mottling of skin, tremors, startles, flayed fingers or hand in stop position, facial twitches, eye rolling or floating, whimpering,
hiccoughing, spitting up, gagging, or grunting (Rauh, Nurcombe, Achenbach, & Howell, 1987).