Background Hydrotherapy (immersion, or bathing) is used worldwide to promote relaxation and decrease parturient anxiety and pain in labor, but the psychophysiological effects of this intervention remain obscure. Design A pre-test post-test design with repeated measures was used to examine the effects of hydrotherapy on maternal anxiety and pain, neuroendocrine responses, plasma volume shift and uterine contractions during labor. Correlations among variables were examined at three time points (pre-immersion and twice during hydrotherapy). Methods Eleven term women (mean age 24.5 years) in spontaneous labor were immersed to the xiphoid in 37°C water for 1 hr. Blood samples and measures of anxiety and pain were obtained under dry baseline conditions and repeated at 15 and 45 min of hydrotherapy. Uterine contractions were monitored telemetrically. Results Hydrotherapy was associated with decreases in anxiety, vasopressin and oxytocin levels at 15 and 45 min (all p < .05). There were no significant differences between pre-immersion and immersion pain or cortisol levels. Pain decreased more for women with high baseline pain than for women with low baseline levels at 15 and 45 min. Cortisol levels decreased twice as much at 15 min of hydrotherapy for women with high baseline pain as for those with low baseline pain. Beta-endorphin levels increased at 15 min but did not differ between baseline and 45 min. During immersion, uterine-contraction frequency decreased. A positive plasma volume shift at 15 min was correlated with contraction duration. Conclusions Hydrotherapy during labor affects neuroendocrine responses that modify psychophysiological processes.

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Literature on the use of plasma cortisol to quantify psychophysiological stress in humans is extensive. However, in parturition at term gestation the use of cortisol as a biomarker of stress is particularly complex. Plasma cortisol levels increase as labor progresses. This increase seems to be important for maintenance of maternal/fetal wellbeing and facilitation of normal labor progress. Unique physiological and methodological issues involved in the use of cortisol as a biomarker of stress in labor present challenges for researchers. This review examines these issues, suggests mixed methods and within-subject repeated measures designs, and offers recommendations for assay procedures for parturient sampling. Documentation of clinical interventions and delivery outcomes may elucidate relationships among psychophysiological stressors, cortisol and normal labor progress. With attention to these methodological issues, analysis of plasma cortisol may lead to clinical interventions that support normal labor physiology.

While still experimental, measurement of external uterine electromyographic (EMG) activity is a more sensitive and noninvasive method for measuring uterine contractility in human labor than the methods currently used in clinical practice. Hydrotherapy is purported to improve contractility in labor, yet there have been no reports of abdominal uterine EMG activity measured during immersion. To test telemetric EMG equipment and different waterproofing techniques under dry and immersed conditions, the authors recorded surface EMG activity from the abdominal muscles of 11 healthy, nonpregnant women, 22 to 51 years of age. After attaching one pair of electrodes to the skin on either side of the umbilicus and applying the waterproofing material, the authors tested the signal by asking participants to perform a short series of leg lifts while seated in a chair to evoke abdominal muscle contractions. They were then immersed to the chest in a hydrotherapy tub while performing two to three leg lifts over 60 s every 5 min for 60 min with 20 lb of weight suspended from their ankles to counteract the buoyancy effect of water. EMG activity was continuously recorded. They then repeated the dry-measures sequence. While waterproofing remained intact, EMG signals were essentially unchanged between dry and wet conditions. Of the 11 waterproofing applications tested, 10 failed at some point. In the data from the successful application, EMG signals in both channels exhibited stable baselines throughout and an absence of low-frequency artifact. The development of this technique allows for the recording of external uterine EMG activity during hydrotherapy. The authors have begun using it to investigate the effects of hydrotherapy on uterine contractility during human labor.

Women who bathe, report relief of anxiety, menstrual and labor pain and promotion of mental and physical relaxation. The findings do not support the view that bathing is associated with identifiable cultural beliefs; rather, they suggest that bathing is a self-care measure used by women. This practice is likely transmitted from generation to generation by female elders through the oral tradition. Assumptions that race or ethnicity precludes the use of bathing may be faulty. Cautionary instructions should be given to pregnant women who are <37 completed weeks of gestation, to avoid bathing for relief of cramping or contractions and to seek immediate health care evaluation. Study of culturally intact groups may uncover additional themes related to bathing in labor and as a self-care measure for dysmenorrhea.