Gentle human touch studies conducted by Harrison and colleagues used an infant-driven detailed protocol based on each infant's physiologic distress response (heart rate < 100 or > 200 beats per minute for 12 seconds or more, or arterial oxygen saturation levels < 90% for longer than 30 seconds). In the largest study of 84 PT infants (42 in the GHT group), 19% of the infants in the GHT group had to have 1 or more GHT sessions terminated early because of decreased heart rate or oxygen saturations values. The investigators noted that these infants were of lower GAs and birth weight and had higher morbidity levels than infants who did not require early termination of the GHT sessions, suggesting the need for continuous and systematic assessment of the type, amount, and timing of the touch intervention based on each very preterm infant's physiologic stability and behavioral responses. Findings from these GHT studies revealed no significant differences in mean heart rate levels when investigators compared baseline (B), touch (T), and posttouch (PT) phases. Although significant decreases in oxygen saturations were observed from B to PT and T to PT, the differences in the means during these phases were not clinically significant. Levels of motor activity, behavioral distress, and modified behavioral distress all decreased when compared with B and PT. No differences between infants in both groups were noted for weight gain, morbidity scores, or hospital lengths of stay in infants who received GHT when compared with controls.