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.


METHODS
Twenty-one preterm neonates (gestational age; GA) 29-37 weeks; bodyweight (BW): 720-2113 g; postnatal age: 2-126 days), born after at-risk pregnancies (stressed (STR) group), 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 10 s pain stimulus was given on the forefoot and heart rate, respiratory rate and blood pressure were measured at 15 and 30 s, at 1, 2, 3, 4 and 5 min. After 10 s ocular compression six cardiac variables were recorded.


RESULTS
After the pain stimulus the STR-group had a significant increase of heart rate at 15 s and an increase of diastolic 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) followed 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 more parasympathetic.


CONCLUSIONS
We hypothesize that the different sympathetic and parasympathetic reaction patterns of the vital parameters to triggers in the STR-group are due to chronic stress, pointing to an altered maturation of the two components of the autonomic nervous system after chronic intrauterine stress (CIUSTR).
Van Reempts
P J
PJ
Department of Pediatrics, University Hospital, Antwerp, Belgium.
Wouters
A
A
De Cock
W
W
Van Acker
K J
KJ
D000704:Analysis of Variance; D001341:Autonomic Nervous System / Q000503:physiopathology*; D001794:Blood Pressure / Q000502:physiology; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D002908:Chronic Disease; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000502:physiology*; D007429:Intraocular Pressure / Q000502:physiology; D010146:Pain / Q000503:physiopathology; D011247:Pregnancy; D018566:Pregnancy, High-Risk / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology; D012119:Respiration / Q000502:physiology; D012894:Sleep Stages / Q000502:physiology; D013312:Stress, Physiological / Q000503:physiopathology*