Context: The underlying biological mechanisms of stress-related pregnancy complications in humans are still poorly understood. Recent research on pharmacological or physical provocation procedures in pregnant women has resulted in inhomogeneous findings. Furthermore, no studies conducted so far have used a psychosocial stress paradigm at different stages of pregnancy.
Objective: The aim of this study was to identify endocrine, autonomic, and psychological responses to standardized psychosocial stress at different stages of pregnancy.
Design: Ninety healthy women (aged 21-37 yr), including 30 pregnant women at the beginning of the second trimester and 30 women at the beginning of the third trimester, as well as 30 nonpregnant women in the follicular phase of their menstrual cycle, underwent a psychosocial stress test. Salivary free cortisol, alpha-amylase, heart rate, and psychological parameters were repeatedly measured.
Results: Salivary cortisol recovery was significantly prolonged in second-trimester pregnant women (P = 0.04). Cortisol and heart rate increases of both pregnant groups were shown to be comparable with those of the controls. alpha-Amylase increases of both pregnant groups were markedly attenuated compared with nonpregnant women (P = 0.008).
Conclusions: From these data, we conclude that, in contrast to pregnancy in rats, pregnancy in women does not result in a restraint of the hypothalamic-pituitary-adrenal axis to psychosocial stress. Furthermore, attenuated alpha-amylase stress response might reflect protective processes within the autonomic nervous system during pregnancy, whereas prolonged cortisol recovery during the beginning of second-trimester pregnancy might be associated with the vulnerability to stress-related pregnancy complications during this period of time.