Effects of relaxation on psychobiological wellbeing during pregnancy: A randomized controlled trial
Introduction
Prenatal maternal stress is associated with several adverse consequences like enhanced risk for preterm delivery, foetal growth restriction, and low birth weight (Alder et al., 2007, Diego et al., 2006, Field et al., 2004, Lopez Bernal, 2007, Makrigiannakis et al., 2007). Moreover, some studies have shown an association of maternal stress and anxiety with increased arterial blood pressure as well as decreased uterine blood flow (Field et al., 2006a, Glover, 1999, Sjöström et al., 1997, Teixeira et al., 1999). Pregnancy-related health problems like preeclampsia or pregnancy-induced hypertension are associated with elevated maternal stress hormone levels (Hernandez-Valencia et al., 2007, Laatikainen et al., 1991). In addition to these longitudinal studies, experimental research has shown that foetuses show physiological reactivity when their mothers are exposed to a stressor (DiPietro et al., 2003, Fink et al., 2009), which is more pronounced in women with high levels of mental health problems (Monk et al., 2000, Monk et al., 2003, Monk et al., 2004).
Enhanced levels of stress, anxiety and depressed mood have been found in pregnancy to be associated with altered physiological parameters. For example, when experiencing stress or mental health problems, pregnant women's peripheral physiology is characterized by an up-regulated activity of the hypothalamic-pituitary–adrenal (HPA) axis (de Weerth and Buitelaar, 2005, Obel et al., 2005). The HPA is one of the primary stress systems in humans and regulates the release of glucocorticoids such as cortisol (Johnson et al., 1992), whereas the sympathetic-adrenal-medullary (SAM) system, a second important regulator of human stress reactivity, releases the catecholamines norepinephrine (NE) and epinephrine (E). During pregnancy, catecholamine levels have been found to be elevated in women with occupational stress (Katz et al., 1991). Assessment of E and NE is relatively uncommon during pregnancy since they need to be measured in blood plasma and have half-lives of only about 2 min in circulation (Ganong, 2001). Indirectly, SAM activity can be assessed by measuring blood pressure and heart rate changes (de Weerth and Buitelaar, 2005).
How these altered physiological processes in pregnant women contribute to adverse pregnancy outcomes is not well understood. Moreover, although research points at the connection between stress in pregnancy and course of pregnancy, foetal development and birth outcomes, there is little knowledge about the benefit of specific interventions for pregnant women to reduce stress. Relaxation techniques such as pleasant guided imagery (GI) (Daake and Gueldner, 1989), or progressive muscle relaxation (PMR) (Jacobson, 1938), have been proven to be reliable methods in reducing self-reported stress and stress-related physiological activity in various non-pregnant clinical populations, as well as in healthy subjects (e.g., Cruess et al., 2000a, Cruess et al., 2000b, Field et al., 1996, Pawlow and Jones, 2002, Pawlow and Jones, 2005, Rider et al., 1985, Tsai and Crockett, 1993, Watanabe et al., 2006). Furthermore, it has been demonstrated that brief psychological interventions with GI and PMR are appreciated by patients undergoing elective resection of colorectal cancer after surgery and have been recommended for implementation in these patients (Haase et al., 2005).
Studies on the impact of relaxation during pregnancy reveal various notable effects (e.g., Beddoe and Lee, 2008 for review). First of all, when exercising regularly, relaxation techniques contribute to a reduction in preterm delivery, longer gestation, increase in birth weight, reduction in caesarean section, and reduction in instrumental extraction (Bastani et al., 2005, Bastani et al., 2006, Field et al., 2004, Field et al., 1999, Nickel et al., 2006, Teixeira et al., 2005, Urizar et al., 2004). The immediate impact of relaxation on pregnant women indicates a reduction in experienced stress or anxiety (Bastani et al., 2005, Bastani et al., 2006, Field et al., 2004, Field et al., 1999, Nickel et al., 2006, Teixeira et al., 2005, Urizar et al., 2004). Further, decreased HPA and SAM reactivity have been documented. Most consistently, cortisol declined after induced relaxation (DiPietro et al., 2008, Field et al., 2004, Teixeira et al., 2005, Urizar et al., 2004), while adrenocorticotropin hormone (ACTH) has not been investigated so far. Effects on NE and E are controversial (Field et al., 2004, Field et al., 1999, Teixeira et al., 2005). Finally, lower heart rate and blood pressure have been observed after practicing a relaxation exercise (Bastard and Tiran, 2006, DiPietro et al., 2008, Nickel et al., 2006, Teixeira et al., 2005).
Although these studies have shown the usefulness of relaxation methods during pregnancy, they are quite diverse and include a wide range of interventions like applied relaxation, massage, hypnotherapy, yoga therapy, verbal instructions, breathing instructions, PMR and GI. Whereas especially yoga therapies (Narendran et al., 2005, Satyapriya et al., 2009) and PMR over a longer period (Field et al., 1999, Field et al., 2004, Nickel et al., 2006) are likely to enhance psychobiological wellbeing, most studies specify only insufficiently the particular content of the interventions, control conditions are often lacking, randomized controlled trials are sparse, and results are heterogeneous with respect to the pattern of variables that are affected by the intervention. In addition, so far only few research groups directly evaluated if different relaxation techniques have a different impact during pregnancy (Field et al., 2006a, Field et al., 2004, Field et al., 1999, Teixeira et al., 2005). Field et al. (1999) compared a massage therapy and a PMR relaxation group over 5 weeks. The massaged pregnant women showed reduced anxiety levels, stress hormones, fewer sleep disturbance, back pain and obstetric and postnatal complications. Women in the PMR group only had decreased anxiety levels after their first session. Teixeira et al. (2005) investigated active versus passive relaxation techniques in pregnant women. Active relaxation was based on hypnotherapeutic methods whereas women in the passive relaxation group sat quietly, reading a women's fashion magazine. A reduction in anxiety and heart rate, but not in stress hormones was found after the active relaxation. The effects of passive relaxation were comparable to those evoked by active relaxation. The diverse outcomes in these studies indicate that different relaxation techniques can have different impact on psychobiological wellbeing in pregnant women.
Therefore, the aim of the present study was to directly compare the immediate effects of two brief active relaxation exercise (PMR and GI) on pregnant women's general psychological, endocrine and cardiovascular functioning. We predicted that – compared to the passive relaxation control condition – both active relaxation techniques will have a positive impact on subjective and objective indicators of relaxation. Active relaxation was hypothesized to elevate the level of perceived relaxation and lead to a greater decline in hormones associated with the HPA-axis and the SAM-system, as well as to reduced cardiovascular activity.
Section snippets
Participants
Pregnant women from the outpatient unit of the University Women's Hospital of Basel, Switzerland, were contacted and informed about the study. If interested in participating, they were invited to a single experimental visit. Women were included if they were German-speaking, over 18-year old, and pregnant with a single, healthy foetus between the 32nd and 34th week of gestation. Accurate dating of gestational age was confirmed by ultrasound in early first trimester. Exclusion criteria were
Sociodemographic and pregnancy-related variables
Participants randomly assigned to the three conditions PMR, GI and CG did not differ in any of the sociodemographic and pregnancy-related variables. Group characteristics are presented in Table 1.
Relaxation
In the ANCOVA, ratings on the relaxation scale showed an immediate Group effect F(2,35) = 6.51, p = .004, d = .61 from pre- to post-relaxation 1 and a significant Group effect, if post-relaxation measurements were averaged (post) F(2,35) = 5.77, p = .007, d = .57. Pairwise group comparisons revealed significantly
Discussion
The present study evaluated the effects of a brief PMR and GI relaxation exercise, as well as a passive relaxation control condition on pregnant women's psychological, endocrine and cardiovascular activity. Our results indicate specific beneficial effects of the active relaxation techniques on pregnant women's psychological and/or cardiovascular state.
So far, only few studies examined levels of anxiety and perceived stress after relaxation exercises, however not using GI as relaxation procedure
Role of funding source
This work is part of the National Centre of Competence in Research (NCCR) Swiss Etiological Study of Adjustment and Mental Health (sesam). The Swiss National Science Foundation (SNF) (project no. 51A240-104890), the University of Basel, the F. Hoffmann-La Roche Corp. and the Basel Scientific Society provided core support for the NCCR sesam.
Conflict of interest
All authors declare that they have no conflicts of interest.
Acknowledgements
This publication is the work of the authors and Corinne Urech, Ph.D. and Judith Alder, Ph.D. serve as guarantors for the paper. The research was specifically supported by the University Women's Hospital of Basel. We are grateful to the biochemical laboratory of the University of Trier, Germany for the biochemical analyses and for their expertise when setting up the study and to Andrea Meyer, Ph.D. for his statistical support.
References (58)
- et al.
Aromatherapy and massage for antenatal anxiety: its effect on the fetus
Complement Ther. Clin. Pract.
(2006) - et al.
Mind–body interventions during pregnancy
J. Obstet. Gynecol. Neonatal Nurs.
(2008) - et al.
Imagery instruction and the control of postsurgical pain
Appl. Nurs. Res.
(1989) - et al.
Physiological stress reactivity in human pregnancy—a review
Neurosci. Biobehav. Rev.
(2005) - et al.
Fetal response to induced maternal stress
Early Hum. Dev.
(2003) - et al.
Fetal responses to induced maternal relaxation during pregnancy
Biol. Psychol.
(2008) - et al.
Synthesis of a cortisol–biotin conjugate and evaluation as a tracer in an immunoassay for salivary cortisol measurement
J. Steroid Biochem. Mol. Biol.
(1992) - et al.
Prenatal depression effects on the fetus and newborn: a review
Infant. Behav. Dev.
(2006) - et al.
Stability of mood states and biochemistry across pregnancy
Infant Behav. Dev.
(2006) - et al.
Effects of neuropeptide Y and noradrenaline on uterine artery blood pressure and blood flow velocity in the pregnant guinea-pig
Regul. Pept.
(1990)