s a result of being born prematurely.
             In their study Johnston and Stevens compared a group of 28 week preterm infants at the age of 4 weeks (post-conceptional age of 32 weeks) with a group of 4 day old neonates who had been born at 32 weeks, i.e the two groups of infants had the same post-conceptional age. They found that the infants born at 28 weeks had increased cardiovascular responses and decreased behavioural responses compared to the infants born at 32 weeks. Johnston and Stevens like Barker and Rutter 1995 found that the differences between the two groups could be directly correlated to the number of invasive surgical procedures.
             Numerous other studies, Herzog et al 1983 and Grunau 1994 have also shown that repetitive painful experiences can modify the physiological and psychological responses to later life pain. Some studies like the neonatal circumcision research carried out by Taddio et al 1995 and 1997 show that this occurs in the full term infant as well. Taddio et al 1997 prospective
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