STRESS RESPONSES IN PRETERM NEONATES AFTER NORMAL AND AT-RISK PREGNANCIES

Objective: To evaluate the autonomic response in preterm neonates born after an at-risk pregnancy. Methodology: Twenty-one preterm neonates (gestational age; GA) 29-37 weeks; bodyweight (BW): 720-2113 g; postna tal age: 2-126 days), born after at-risk pregnancies (stressed (STR) g roup), were compared to 30 preterm neonates (GA: 26-36 weeks; BW: 813- 2380 g; postnatal age: 2-86 days) without any intrauterine risk factor (C group). A 10s pain stimulus was given on the forefoot and heart ra te, respiratory rate and blood pressure were measured at 15 and 30 s, at 1, 2, 3, 4 and 5 min. After 10s ocular compression six cardiac vari ables were recorded. Results: After the pain stimulus the STR-group ha d a significant increase of heart rate at 15 s and an increase of dias tolic blood pressure at 30 s. In the C group a significant increase of heart rate at 15 s was recorded. For the respiratory rate both groups showed an initial depression (significant at 15 s in the C group) fol lowed by an increase. The time to react to the ocular compression was significantly shorter in the STR-group than in the C-group and thus mo re parasympathetic. Conclusions: We hypothesize that the different sym pathetic and parasympathetic reaction patterns of the vital parameters to triggers in the STR-group are due to chronic stress, pointing to a n altered maturation of the two components of the autonomic nervous sy stem after chronic intrauterine stress (CIUSTR).