CHILDBIRTH AS A BIOLOGICAL MODEL FOR STRESS - ASSOCIATIONS WITH ENDOCRINE AND OBSTETRIC FACTORS

Objective: The aims of this investigation were to measure corticotropi n-releasing hormone (CRH), corticotropin (ACTH) and cortisol before, d uring and after delivery searching for an endocrine intercorrelation o f the hypothalamic-pituitary-adrenal (HPA) axis and to correlate these findings with obstetrical variables. Methods: Blood was sampled from 50 women with singleton pregnancies at term without uterine contractio ns, during delivery (after full cervical dilatation) and on the 4th po stnatal day. Hormones were measured by radioimmunoassay (RIA). The cor relation between obstetric variables, sociodemographic and endocrine d ata were evaluated using the Spearman rank coefficient. Group comparis ons for continuous variables were calculated using the Mann-Whitney U test and Kruskal-Wallis test. Results: Maternal plasma ACTH and cortis ol increased significantly during labor, declining toward the 4th post natal day (p < 0.001) and showing a significant intercorrelation (p < 0.01). Compared to women without uterine contractions CRH rose during labor (p < 0.05) and decreased rapidly to the 4th postnatal day (p < 0 .001). No correlations between CRH and ACTH or cortisol were observed. None of the obstetrical variables (parity, newborn's weight, duration of delivery) revealed any significant correlation with ACTH. Analgeti c medication (pethidine hydrochloride) was not able to influence the e ndocrine response to labor stress. Conclusions: Stressful experience d uring childbirth has an impact on endocrine response. However, this is not fully evident along the HPA axis in a simple biological model wit h monocausal dependencies. This 'biological stress model' is not sensi tive enough to detect different childbirth conditions and the hormones in the maternal compartment. have partially fetal (placental) origin.