The Effect of Yoga on Menstrual Disorders: A Systematic Review

Abstract

Objective:

To summarize and evaluate evidence for the effect of yoga on menstrual disorders.

Methods:

PubMed, CINAHL/MEDLINE, Web of Science, AMED, and Scopus were searched for English-language literature relevant to the review question. All primary research studies were included.

Results:

Fifteen studies described in 18 papers were included in the review. A range of yoga interventions were used. Some studies used a combination of Asana, Pranayama, and other yogic relaxation or meditation techniques. All included studies reported some change in their outcome measures, suggesting reduced symptoms of menstrual distress following a yoga intervention; however, the heterogeneity and intensity of the interventions and outcome measures meant that findings have limited generalizability and applicability in practice settings.

Conclusions:

Further research on the relationship between yoga practice and menstrual disorders is warranted, but there must be both consistency in the methods, measures, and quality of studies and a shift toward research on yoga practices that are replicable outside of the clinical trial setting.

Introduction

This article reviews the evidence for the effect of yoga practice on common menstrual disorders in premenopausal women. Common primary menstrual disorders include amenorrhea (lack of menstruation), oligomenorrhea (irregular menstruation), dysmenorrhea (painful menstruation), premenstrual syndrome (PMS, which incorporates cyclical psychological and physical symptoms), and premenstrual dysphoric disorder (a severe form of premenstrual syndrome).¹ Menstrual disorders are common. Prevalence of PMS and premenstrual dysphoric disorder have been reported as ranging from 5% to 8%.² Prevalence rates for dysmenorrhea range from 16% to 91%.³ Surveys of women in developing countries, the United States, Europe, and Australia have found that 5%–20% of women report dysmenorrhea to the extent that it stops them from participating in usual activities.⁴ Menstrual disorder is also a component of the female athletic triad (along with osteoporosis and disordered eating), the prevalence of which among female athletes is between 0% and 15.9%.⁵ Where medical assessment and treatment of menstrual disorders should in the first instance establish whether they are secondary to other conditions (such as polycystic ovarian syndrome, thyroid problems, menopause, or pregnancy),⁶ many women choose to manage their menstrual problems through the use of complementary and alternative therapies, including the practice of yoga.^7
–9

Background

Yoga is a term used to describe a variety of practices, although its literal translation in Sanskrit means “yoke” or “union.”¹⁰ Yogic practices may include physical exercises (Asanas), breathing exercises (Pranayama), relaxation techniques, and meditation or concentration practices, including yoga Nidra (a form of guided relaxation practice). There are many different types of yoga, according to different schools or traditions (for example the Asana-heavy styles of yoga practiced often in the West according to the teachings of three pupils of Krishnamacharya (1889–1989): the school of BKS Iyengar,¹¹ Ashtanga Vinyasa yoga of Patthabi Jois,¹² and the Viniyoga of Desikachar¹³). Yoga practice in the modern context is primarily focused on Asana as a physical exercise regimen, whereas traditionally, and certainly before the mid-20th century, yoga has been more widely associated with spirituality and contemplation, with Asana practice being a less prominent aspect.¹⁴

Research on yoga as a therapeutic intervention grows apace,^15
–17 although the variability in study quality, interventions, and outcome measures means that the extent to which yoga practice may positively affect health cannot yet be definitively stated.^15,16 The mechanism by which yoga may improve health is commonly considered to be its effect on the autonomic stress response.¹⁸ Yoga-based practices affect a complex series of physiologic and cognitive mechanisms, which in turn may affect aspects of self-regulation of stress.^19
–21

A recent attempt to define a comprehensive theoretical framework from which hypotheses on how bottom-up neurophysiologic and top-down cognitive mechanisms may explain the effect of yoga on well-being has differentiated between the effects of the movement, breath and attention aspects of practice.¹⁹ It has also differentiated between several neurologic and physiologic processes that may be involved in self-reported changes in the well-being of yoga practitioners. These include the effect of yoga movement on the basal ganglia and cerebella circuits; the influence of yoga breathing practices on concentrations of oxygen and carbon dioxide in the blood; and the effect of the attention element of practice, akin to other meditative activities, on structural changes in parts of the brain responsible for bodily awareness.

Alongside the exponential increase in yoga research, there has been “a parallel surge” in yoga practice.¹⁶ Demographic surveys of yoga practitioners in the United States have found yoga practitioners to be more likely to be white, female, highly educated, and middle aged.^22,23 As well as the trial-based evidence showing that yoga may positively affect health, in particular the psychology and physiology of stress, there are practical benefits to suggesting yoga as an intervention for menstrual disorders: It is not costly, requires no equipment, and is readily available (there are classes in most cities, and yoga tutorials are available online). A recent meta-analysis of clinical trials found yoga to be as safe as usual care or exercise.²⁴

A relationship between yoga Asana practice and menstrual disorder symptoms has been established in both the nonacademic popular literature and in yoga manuals. In the grey nonacademic literature (namely, the plethora of yoga websites and magazines and mentions of yoga on health and well-being websites), there is evidently an association between frequent yoga practice and oligomenorrhea, and the possible effects of yoga on menstrual disorders (a Google search of “yoga AND menstrual disorders” yielded about 340,000 results on November 6, 2016, and a search of “yoga AND oligomenorrhea” yielded about 36,000 results on November 6, 2016).

Commonly in yoga manuals and instructional articles, women are advised to refrain from certain Asanas, such as the inversion postures Sirsasana (headstand) or Sarvangasana (shoulder stand) during menstruation,²⁵ whereas in the Ashtanga Vinyasa tradition of Patthabi Jois,¹² women are advised to refrain from Asana practice in the first 3 days of menstruation off from practice.²⁶ Popular yoga manuals offer women specific sequences to be undertaken during menstruation. For example, Geeta Iyengar's Yoga: A Gem for Women ²⁷ recommends a sequence including Upavistha Konasana and Baddha Konasana to ease dysmenorrhoea, and Judith Hanson Lasater offers a sequence for menstruating women in The Moon Club: Honouring the Monthly Cycle,²⁸ which aims to assist the body in releasing menstrual flow, reducing fatigue, and moderating hormonal shifts. Like Iyengar, her sequence is based around versions of Baddha Konasana and Upavistha Konasana. The sequence of postures recommended for menstruation on the online Yoga Journal site²⁹ include Baddha Konasana, Dhanurasana (the bow), Setu Bandha Sarvangasana (bridge pose), Ustrasana (the camel), dolphin, and Adho Mukha Svanasana (downward dog). The PopSugar lifestyle site article “Skip the Ibuprofen and Do These Yoga Poses to Ease Period Pain”³⁰ suggests a “half bound squat” (Malasana), arching pigeon (Kapotasana), one-armed camel (Ustrasana), a wide child's pose (Balasana), and a reclining twist, although the first three of these poses are rather advanced and would probably not be taught in a beginner's class.

The aim of this review was to assess the evidence for correlations between yoga practice and various forms of menstrual disorder and to identify which forms of yoga have been evaluated as interventions for menstrual disorders. The review also aimed to evaluate the published primary research evidence for the efficacy of yoga as an intervention for treating menstrual disorders. Does published research evidence accord with yoga wisdom, as reflected in journals, websites, and instruction manuals?

Methods

This study was a systematic literature review of primary research on the effect of yoga on menstrual disorders. A search was conducted of the English-language literature between 1996 and 2016. The following databases were searched: PubMed, CINAHL/MEDLINE, Web of Science, AMED, and Scopus. The following search terms were used: “Yoga AND menstruation OR menstrual period OR menarche; Yoga AND amenorrhea; Yoga AND dysmenorrhea.” Studies were included if the following criteria were met: primary research, on premenopausal women, and undertaking yoga practice. Studies were excluded if their participants were menopausal women, if yoga was not the intervention being undertaken. and if the study did not consist of primary research. This study aimed to comprehensively review all research literature on the effect of yoga on menstruation, not just evidence from randomized controlled trials (RCTs), so all types of primary research study were included.

One reviewer reviewed each paper by using a standardized data extraction form. Extracted data included authors, year of publication, sample size, interventions, main outcomes, and adverse events. The data extraction process is detailed in Figure 1.

FIG. 1.

Flowchart of the results of the literature search.

The methodologic quality and risk of bias of the included studies were measured by using the Critical Appraisal Skills Programme (CASP) criteria³¹ and the Cochrane Handbook for Systematic Reviews of Interventions (version 5.0.2).³² The following domains of bias were reviewed: random sequence generation, allocation concealment, blinding of participants and personnel, incomplete outcome data, selective reporting, and other sources of bias.

Results

Fifteen studies described in 18 papers were included in the review. The year of publication, authors, study design, sample size, age of participants, intervention modality, intervention dosage, outcome measure, and salient findings for each study are reported in Table 1. Three were case-control trials comparing women with menstrual disorders and healthy women. Nine studies were RCTs. Three were intervention studies. Eight studies were conducted in India; three were conducted in Taiwan; and one each was conducted in Iran, Japan, and Korea. The included studies measured the effect of yoga on premenstrual symptoms and menstrual distress. No studies measured the effect of yoga on amenorrhea or oligomenorrhea. No studies measured the effect of yoga on menstruation in women who were regular yoga practitioners.

Table 1.

Summary of Studies Examining the Role of Yoga in the Treatment of Menstrual Disorders

Year	Authors	Design and sample	Age (yr)	Intervention modality	Intervention dosage	Outcome measure	Salient findings
2013	Chien et al.	Case-control study; 30 women with primary dysmenorrhea; 30 healthy controls	18 and older	Asana (static poses) and relaxation	Twice weekly for 30 min for 8 wk	Short-form MDQ; serum homocysteine and nitric oxide	Yoga intervention associated with lower MDQ scores (p < 0.05) and associated with lower homocysteine
2013	Choudhary and Mishra	RCT; 32 women reporting premenstrual distress	18—30	Asana, Pranayama (Anuloma Viola and Kapalabhati), Yoga Nidra	Daily for 90 min for 16 wk	Impaired concentration, water retention, and negative affect categories of the WHAQ	Yoga intervention associated with lower negative affect (p < 0.0001); lower water retention (p < 0.001); lower impaired concentration (p < 0.00001)
2015	Ganesh et al.	Intervention study; 90 young women reporting primary dysmenorrhea	18–25	Comparison of 2 Pranayama techniques (group A: Nadi Shodana vs. group B: Kapalabhati)	10 min of practice daily for 2 menstrual cycles	MDQ; numeric pain rating; QoL scale	Significant difference in QoL and pain scores in group A compared with group B
2013	Kanojiia	RCT; 50 healthy women (25 intervention; 25 control)	18–20	Asana, Pranayama (including Nadi Shodana); relaxation; meditation	40 min for 6 d a wk for 3 menstrual cycles	Autonomic and parasympathetic tests; isometric grip test; anxiety, depression, anger, and sense of well-being scales	Significantly greater decrease in body weight, heart rate, and systolic and diastolic blood pressure; anger, depression, and anxiety and increase in well-being score in yoga group compared with control group from initial to third cycle
2013	Nag and Kodali	RCT; 113 medical students (60 intervention, 53 control) with primary dysmenorrhea and stress	18–23	Asana	60-min class every day for 6 mo	Pain numerical rating scale; PSS	Significant (p < 0.0001) reduction in pain and perceived stress in the intervention group
2013	Nidhi et al.	RCT; 90 students with adolescent polycystic ovary syndrome	15–18	Intervention: lecture, Asanas, Pranayama, relaxationControl: exercises, rest, nonyogic breathing	1 h daily for 7 d a week for 12 wk	Anti-Müllerian hormone, LH, FSH, modified Ferriman and Galleway score for hyperandrogenism, testosterone, prolactin, BMI, hirsutism, menstrual frequency	Yoga intervention was more effective than control in decreasing anti-Müllerian hormone, LH, testosterone, and modified Ferriman and Galleway scores and increasing menstrual frequency, with no change in body weight, FSH, or prolactin
2013	Parkhad	Intervention study; 200 adolescents	13–17	Asana and Pranayama	45 min daily for 6 mo	Z scores for reported menstrual cycle disorders, menstrual cycle length, bleeding phase	Reduction in dysmenorrhea (Z value, 12.1), normalization of menstrual cycle, menstrual bleeding phase, menstrual blood loss, reduction in backache, concentration, complaints
2011	Rakhshaee	RCT; adolescents with primary dysmenorrhea (50 experiment, 42 control)	18–22	3 yoga Asanas (cat, cobra, fish)	20 min daily for 14 d of a menstrual cycle for 3 cycles	Menstrual characteristics questionnaire, including VASP	Significant difference (p < 0.05) in pain and intensity before and after for the intervention group, and between the intervention and control group
2016	Rani et al.	RCT; 87 women with diagnosed menstrual disorders (45 intervention, 42 control)	18–45	Yoga Nidra	30–35 min per d for 5 d a week for 3 mo	Psycho-biological General Well-being Index; levels of TSH, FSH, LH, prolactin, progesterone, estradiol, testosterone, and dehydroepiandrosterone sulfate	Intervention group: improved mean score of anxiety, epression, positive well-being, general health, and vitality scores (p < 0.05), but not in control group; significant changes in TSH (p < 0.02), FSH (p < 0.01), LH (p < 0.001), and prolactin (p < 0.03) in intervention compared with control group
2013, 2012, 2011	Rani et al.	RCT; 126 women diagnosed with menstrual disorders (65 intervention; 61 control)	Intervention: 28.53 ± −7.07; control: 27.62 ± 7.78	Yoga Nidra	35–40 min per day 5 d a week for 3 mo	TSH, FSH, LH, and prolactin in blood samples Autonomic function tests; heart rate variability; symptom severity	Decreases in TSH (p < 0.002), FSH (p < 0.02), LH (p < 0.001), and prolactin (p < 0.02) in intervention versus control group Significant improvements in blood pressure, postural hypotension, and sustained hand grip, heart rate expiration inspiration ratio, and 30:15 beat ratios; no significant (p < 0.05) relief from menstrual symptoms
2012	Sakuma et al.	RCT; 68 healthy female nursery and kindergarten teachers	20–64	Home-based yoga (Asana and Pranayama) DVD	5 min 45 Asana; 1 min 45 Pranayama every day for 2 wk then 4-wk follow-up	VAPS; GHQ30; BMI; flexibility; grip test; reach test	Menstrual pain reduced in the good adherence group (p < 0.044) and compared to control (p < 0.028); GHQ total scores improved in intervention group (p = 0.004)
2013	Sharma et al.	Case-control study: 60 women with menstrual distress and 30 healthy controls	18–40	Control group vs. group A (no intervention); group B (Anuloma Viola); group C (yoga Asana)	Daily on 7 d before date of menstruation for 3 consecutive cycles	Physiologic relaxation response via heart rate, blood pressure, electromyogram, galvanic skin response, respiratory rate, peripheral temperature	Heightened relaxation response in groups b and c compared to control group A
2016	Tsai	Intervention study; 64 healthy women workers at a manufacturing plant	20–45	Kapalabhati Pranayama, Asana, relaxation	50-min classes twice per week for 12 wk	Self-reported menstrual pain and premenstrual symptoms, SF-36 Health survey	Significant decrease in prevalence of abdominal swelling (p = 0.0011), breast tenderness (p = 0.0348), abdominal cramps (p = 0.0016), and cold sweats (p = 0.0143; improvement in 6 scales of the SF-36, including physical function (r = 0.529), bodily pain (r = 0.365), general health perception (r = 0.280), vitality/energy (r = 0.351), social function (r = 0.318), and mental health (r = 0.3555)
2015	Wu et al.	Case-control study; 11 women with premenstrual syndrome, 9 controls	20–30	Pranayama, Asana, relaxation	50 min twice weekly for 6 wk	Resting EEG and cognitive functioning 2-back task	Alpha-wave percentage increase in intervention group immediately after exercise; no effect on menstrual cycle; yoga enhanced accuracy and reaction time in the 2-back test
2016	Yang and Kim	RCT; 40 women with primary dysmenorrhea (20 intervention, 20 control)	18–25	Asana, yoga Nidra	1 h per week for 12 wk	VASP, pain duration report, modified short-form MDQ	Significant decrease in menstrual pain intensity (p = 0.001) and menstrual distress (p < 0.0001) scores in the intervention compared with the control group

MDQ, Menstrual Distress Questionnaire⁵¹; RCT, randomized controlled trial; WHAQ, Women's Health Assessment questionnaire (original source not given by Choudhary and Mishra⁴⁰); QoL, Quality of Life scale (original source not given by Ganesh et al⁴²); PSS, Perceived Stress Scale⁵⁷; LH, luteinizing hormone; FSH, follicle-stimulating hormone; BMI, body–mass index; VASP, Visual Analogue Scale for Pain⁵²; TSH, thyroid-stimulating hormone; GHQ30, General Health Questionnaire (Japanese version)⁵⁸; SF-36, Short-Form Health Survey⁵⁹; EEG, electroencephalography.

Participant characteristics and recruitment

The age range of female participants in the studies varied between 13 and 45 years. In two studies, participants were adolescent girls who attended residential colleges.^33,34 Other studies recruited participants through referral from and attendance at gynecology clinics,^35

–40 on students at a metropolitan college,⁴¹ students on a physiotherapy course,⁴² female volunteers with no stated specific origin,⁴³ unmarried medical students,⁴⁴ students,⁴⁵ nursery and kindergarten teachers,⁴⁶ staff and students at a university,⁴⁷ female workers at an electronics factory,⁴⁸ college students,⁴⁹ and nursing college students.⁵⁰

Interventions

A range of yoga interventions were used. Some studies used a combination of Asana, Pranayama, and other yogic relaxation or meditation techniques. Two studies^35

–39 measured the sole impact of Yoga Nidra practice. One study⁴⁶ measured the effect of three specific yoga Asanas (cobra, cat, and fish). In other studies, a range of Asana were practiced. The length of the yoga practice sessions differed between studies, from 10 minutes⁴² to 90 minutes.⁴⁰ Frequency of practice ranged from daily for 16 weeks⁴⁰ to 20 minutes for 14 days.⁴⁵ In one study,⁴⁶ participants were taught the Asana routine and then given a DVD to use for home practice. In the other studies, instruction was provided in a class setting. One study⁴² compared the efficacy of two Pranayama techniques. In another study,³⁴ the control group undertook nonyogic exercise, breathing and resting at the same time as the yoga intervention group. The control groups in the other RCTs and case-control studies did not take part in a control intervention.

Outcome measures

There was little consistency between studies in the outcome measured used. Some studies used versions of the Moos Menstrual Distress Questionnaire (MDQ);⁵¹ others used pain scales, primarily the Visual Analogue Scale for Pain⁵² and general quality of life and stress scales (Table 1). Mood scales and mental health scales were also used. In some studies, physiologic assessments were used as objective measures of impact and to identify underlying mechanisms for the potential effect of yoga on menstrual distress. These included the use of resting electrocardiography, body mass index, hand grip and reach tests, autonomic function tests, and serum levels of hormones at certain points in the menstrual cycle.

Findings

All studies reported a beneficial effect of yoga as an intervention for menstrual disorders. Yoga practice was associated with lower MDQ scores,^41,50 lower serum homocysteine,⁴¹ lower negative affect,⁴⁰ reduced pain scores,^42
–44,48 increased well-being scores,^38,43 autonomic system changes,^33,35
–37 a heightened relaxation response,⁴⁷ and decreased menstrual disorder symptoms.⁴⁸ No study concluded that yoga had no effect on menstrual disorder symptoms.

Only one study³⁸ reported an adverse effect of the yoga intervention; namely, one participant dropped out because of “nonrestorative sleep” following the yoga Nidra practice. Only three studies confirmed no adverse effects of the practice (because of reporting of the included studies).^40,45,49 In all other studies there was no mention of adverse effects or affirmation of their being no adverse effects.

Quality of studies

The quality of studies was assessed by using CASP criteria.³¹ All studies gave clear statements of their methods and aims. Recruitment strategies, data collection, and analysis methods were stated. Two studies^39,40 did not state that it had been approved by an ethics committee or institutional review board. All studies described the use of appropriate statistical analysis techniques.

While the research methods and aims were replicable, description of the yoga intervention used varied, limiting the replicability of the intervention in future research. Most studies described the specific Asana used in their intervention, with the exception of Nidhi et al.³⁴ and Sakuma et al.⁴⁶ The studies focused on Yoga Nidra as an intervention^35
–37,39 did not give detail of how Yoga Nidra was instructed or performed. There was limited discussion of the rationales for the specific Asana and Pranayama chosen for the interventions.

High risk of bias was identified in three studies^33,40,48 (Table 2) due to high attrition rates, lack of description of randomization methods, and sole use of subjective self-report methods to measure outcomes. Given the nature of the interventions, it was not possible to blind participants to their allocation or the intervention. Where several studies used self-report measures, such as pain analogue scales, there was a risk of bias in outcome assessment.

Table 2.

Risk of Bias

	Selection bias
Study (year)	Random sequence generation	Allocation concealment	Performance bias: blinding of participants and personnel	Detection bias: blinding of outcome assessment	Attrition bias: incomplete outcome data	Reporting bias: selective reporting	Other bias: any other concerns	Risk of bias
Chien et al. (2013)	No	NA	NA	Self-report measure and blood test (objective measure)	NA	NA	NA	Low
Choudhary and Mishra (2013)	Randomization method not described	NA	NA	Self-report measures	61% dropout rate	Yes; high dropouts	NA	High
Ganesh et al. (2015)	Randomization method not described	NA	NA	Self-report measure	NA	NA	NA	Low
Kanojia (2013)	Randomization method not described	NA	NA	Self-report and objective measures	NA	NA	NA	Low
Monika et al. (2012), Rani et al (2011a, 2011b, 2013)	Yes	NA	NA	Both subjective and objective	NA	NA	NA	Low
Nag and Kodali (2013)	Yes	NA	NA	Self-report measures	No attrition	NA	NA	Low
Nidhi et al. (2013)	Yes	NA	NA for part but yes for analysts	Objective measures	20% dropout rate	No	No	Low
Parkhad (2013)	No	NA	No	Self-report measure	No	No	No	High
Rakhshaee (2011)	Cluster random	NA	No	Self-report measure	23% dropout rate	No	No	Low
Rani et al. (2016)	Yes	NA	No	Both subjective and objective	13% dropout rate	No	No	Low
Sakuma et al. (2012)	Yes	NA	No	Both subjective and objective	31% dropout rate	No	No	Low
Sharma et al. (2013)	No	NA	No	Objective measures	No attrition	No	Limited information in report	Low
Tsai (2016)	No	NA	NA	Self-report measures	68% dropout rate	Yes; high dropouts	Dropout due to difficulty completing 12-wk course	High
Wu et al. (2015)	Yes	No	No	Objective measures	29% dropout rate	No	No	Low
Yang and Kim (2016)	Yes	No	No	Self-report measure	No dropouts	No	No	Low

NA, not available.

While all studies reported some positive effect of yoga on menstrual distress, as reported by participants and as found by assessing physiological correlates of menstrual distress, the external validity of the studies is limited by the frequency of the interventions used, with daily practice under instruction being an unrealistic expectation of most working-age women. This concern has also been raised in a review of yoga for menopausal symptoms.⁵³ No studies included long-term follow-up, meaning that the continued effect of the intervention was not measured.

Discussion

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 Nidra ^35,36

–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.

Strengths and weaknesses

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.

Implications for further research

The results of the studies included here suggest that further research is warranted. There is a need for consistency of measurement and intervention in studies of the efficacy of yoga for menstrual disorders. Long-term follow-up should be included in research designs. The effect of different aspects of yoga practice (Asana, Pranayama, Yoga Nidra, relaxation, and meditation) as well as the different styles of yoga should be compared, rather than treated as one intervention. Yoga interventions should be designed to be realistically followed by working-age women so that they may be generalized to the wider population. There have been no studies in this field on western women. No baseline studies have measured the presence of menstrual disorders in regular yoga practitioners. Of particular interest is the extent of amenorrhea or oligomenorrhea in frequent practitioners of the more strenuous forms of yoga, such as Ashtanga.

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.

Conclusion

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.

Footnotes

Author Disclosure Statement

No competing financial interests exist.

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