Stress responses to tilting and odor stimulus in preterm neonates after intrauterine conditions associated with chronic stress.

The effect of conditions linked with chronic intrauterine stress (CIUSTR) on the function of the autonomic nervous system (ANS) has not yet been evaluated systematically in premature neonates. We hypothesized that intrauterine stress deranges the function of the ANS as assessed by the clinical responses to certain stimuli. Twenty-one premature neonates who had suffered from CIUSTR, such as maternal smoking, maternal hypertension, and intrauterine growth retardation (STR Group), and 30 neonates who had not suffered from those intrauterine conditions were studied (C Group). They were exposed to a 10-s postural change test and a 10-s odor test. Heart rate, respiratory rate, and noninvasive blood pressure were measured at 15 s, 30 s, and at 1, 2, 3, 4, and 5 min after the test. The overall reaction pattern after the postural change test was mainly sympathetic, and was more pronounced in the STR Group. After the odor test, the overall response was parasympathetic but less pronounced in the STR Group. We, therefore, speculate that neonates who suffer from conditions known to be associated with CIUSTR exhibit a higher adrenergic state with little reserve to counteract stressful situations that may make them more vulnerable.