TIME (5/2, MacMillan) reports “yoga may provide relief from” menstrual cramps, PMS, and other conditions, “according to a new review of studies published in the Journal of Alternative and Complementary Medicine.” Researchers reviewed “15 studies that looked at how a regular yoga practice affects a woman’s experience of cramps, PMS, polycystic ovary syndrome (which can cause missed or infrequent periods) and premenstrual dysphoric disorder,” and “found that yoga was linked to reduced severity of symptoms and pain relief in women suffering from these conditions.”
Yoga is a term used to describe a range of practices, following a number of traditions of schools.10 The findings of this review mirror those of systematic reviews of yoga for other health conditions, in that the positive outcomes of individual studies must be countered by concerns about their lack of replicability and their heterogeneity.12,48,49 Yoga practice is growing exponentially,24 particularly in the population most likely to experience menstrual distress: women of childbearing age.
The complex mechanisms by which yoga practice may affect the person cognitively and physiologically, with an assumed impact on the stress response, have been noted earlier.19–21 The effect of yoga specifically on the underlying mechanisms of menstrual disorder is therefore hard to determine here. The reduction of menstrual disorder symptoms (as reflected in pain or well-being scores) may be due to a generic effect of yoga on pain tolerance and stress reduction, rather than an impact on underlying causes of menstrual disorder, such as hormone imbalance, for example.
While the studies did discuss the possible and previously trialed benefits of yoga, there was no rationale for the specific regimens that were followed: neither the sets of postures used in the interventions nor the duration and frequency of the intervention. In the studies that used a limited and specific practice, for example, Yoga Nidra35,36–39 or the comparison of two types of Pranayama,42 there was not a justification for these practices over others in the yoga pantheon. The exception is Rakhshaee and colleagues’ study45 using three specific poses. Their use is justified because of the action of the cobra pose on spinal flexibility and muscular strength, the cat pose on movement and breath coordination, and the fish pose on relief of stiffness and improvement of flexibility. The mechanism by which these proposed effects address menstrual disorder requires further inquiry, however.
All included studies reported some change in their outcome measures suggesting reduced symptoms of menstrual distress following a yoga intervention; however, the interventions and outcome measures used varied considerably. Several studies documented the effect of intensive programs of daily yoga that may be difficult to sustain outside of the college or industrial settings of the studies, whereby the same groups of women could be present in the same place for several days in a week. Among the 18 studies there was limited parity of intervention or outcome measure. Most studies measured the effect of yoga on an intervention group with no prior experience of yoga practice, meaning that the influence of yoga on menstruation over the long term or in regular practitioners was not gauged. Frequency of practice is a predictor of good health and high subjective well-being in established practitioners;22 however, the regimens described for yoga novices in some studies in this cohort were particularly intensive.33,34,40,43,44 There is scope for future research that both controls for the effect of frequency and duration of practice on menstrual disorders and explores the specific influence of frequency and duration.
Another main methodologic drawback is lack of comprehensive reporting of trial methods and heterogeneity of interventions, as has been identified in reviews of yoga for depression,54,55 weight management,56 and menopausal symptoms.53 A recent comprehensive review of research on yoga 2010 to 2016 concluded that RCTs should compare yoga to other forms of exercise and that physiologic tests to identify underlying mechanisms should be used rather than self-reported measures.15 Recent systematic review and meta-analyses of yoga intervention studies for physical and mental health conditions have also called for a more sophisticated approach, whereby aspects of the practice and characteristics of different practitioners are explored.
This was the first systematic review of studies of yoga and menstrual disorders in women of childbearing age, including RCTs. A limitation of this review was the lack of eligible studies and lack of similarity between studies. Another limitation was the restriction to English-language studies. There was no research available on amenorrhea and yoga or oligomenorrhea and yoga. Evidence from yoga manuals, Internet searches, and the nonacademic literature suggests that the effect of yoga practice on menstrual disorders may well extend beyond it being a possible treatment, and that frequent practice may be implicated in the genesis of menstrual disorders as well as potentially relieving them. Such a relationship has not been explored in primary research.
Future studies should follow rigorous reporting and methodologic standards, meaning that their design should address risks of bias, particularly in randomization, outcome measures used, and reporting bias. The challenge of allocation concealment and blinding of participants should be acknowledged.
This systematic review found several studies presenting evidence for the effectiveness of yoga as an intervention for symptoms of menstrual disorder. The lack of consistency in the interventions and outcome measures used precluded meaningful meta-synthesis. No studies have looked at the long-term effects of yoga practice on menstrual disorders or the prevalence of menstrual disorders in long-term yoga practitioners. The results of this review suggest that further research on yoga for menstrual disorders is warranted, so long as both methodologic standards are met and the study design enables generalizability to the target population.