Additional GHT studies have been conducted by Harrison and colleagues. Preterm infants enrolled in these studies ranged from 27 to 33 weeks' GA, with the touch intervention commencing 6 to 9 days after the birth. Similar to Jay's study, these GHT studies used a trained research nurse or occupational therapist who placed one hand on the infant's head and one hand on the lower back and buttocks for 10 to 20 minutes, ranging from 1 to 3 times per day, for 5 to 10 days.