Researchers from the OBGYN Department at University Hospital Basel in Switzerland, hypothesizing that adverse birth outcomes can be reduced by relaxation exercises, compared the immediate effects of two active and one passive 10-minute relaxation technique on perceived relaxation and concrete physiological indicators of relaxation in 39 healthy, pregnant women.
The subjects, recruited at the outpatient department of the University Women's Hospital Basel participated in a randomized controlled trial with an experimental repeated measure design.

Participants were assigned to one of two active relaxation techniques: progressive muscle relaxation (PMR) or guided imagery (GI); or a passive relaxation control condition.
Measures were self-reported relaxation on a visual analogue scale (VAS) and state anxiety (STAI-S), as well as endocrine parameters indicating hypothalamic-pituitary-adrenal (HPA) axis (cortisol and ACTH) and sympathetic-adrenal-medullary (SAM) system activity (norepinephrine and epinephrine). Cardiovascular responses (heart rate, systolic and diastolic blood pressure) were also measured, all taken at four time points before and after the relaxation exercise.

Between-group differences showed that, compared to the progressive relaxation and control conditions, guided imagery was significantly more effective in enhancing levels of relaxation, and together with progressive muscle relaxation, the imagery was associated with a significant decrease in heart rate.

Within the groups, passive as well as active relaxation procedures were associated with a decline in endocrine measures except epinephrine.

Taken together, these data indicate that different types of relaxation had differential effects on various psychological and biological stress systems. Guided imagery was especially effective in inducing self-reported relaxation in pregnant women while at the same time reducing cardiovascular activity.

Citation:  Urech C, Fink NS, Hoesli I, Wilhelm FH, Bitzer J, Alder J. Effects of relaxation on psychobiological wellbeing during pregnancy: a randomized controlled trial. Psychoneuroendocrinology. 2010 Oct;35(9):1348-55. Epub 2010 Apr 22. [email protected]