Experiences of menstruation in high income countries: A systematic review, qualitative evidence synthesis and comparison to low- and middle-income countries

Background There is growing recognition of the importance of menstruation in achieving health, education, and gender equality for all. New policies in high income countries (HICs) have responded to anecdotal evidence that many struggle to meet their menstrual health needs. Qualitative research has explored lived experiences of menstruating in HICs and can contribute to designing intervention approaches. To inform the growing policy attention to support people who menstruate, here we review and synthesise the existing research. Methods and findings Primary, qualitative studies capturing experiences of menstruation in HICs were eligible for inclusion. Systematic database and hand searching identified 11485 records. Following screening and quality appraisal using the EPPI-Centre checklist, 104 studies (120 publications) detailing the menstrual experiences of over 3800 individuals across sixteen countries were included. We used the integrated model of menstrual experiences developed from studies in low- and middle-income countries (LMICs) as a starting framework and deductively and inductively identified antecedents contributing to menstrual experiences; menstrual experiences themselves and impacts of menstrual experiences. Included studies described consistent themes and relationships that fit well with the LMIC integrated model, with modifications to themes and model pathways identified through our analysis. The socio-cultural context heavily shaped menstrual experiences, manifesting in strict behavioural expectations to conceal menstruation and limiting the provision of menstrual materials. Resource limitations contributed to negative experiences, where dissatisfaction with menstrual practices and management environments were expressed along with feelings of disgust if participants felt they failed to manage their menstruation in a discrete, hygienic way. Physical menstrual factors such as pain were commonly associated with negative experiences, with mixed experiences of healthcare reported. Across studies participants described negative impacts of their menstrual experience including increased mental burden and detrimental impacts on participation and personal relationships. Positive experiences were more rarely reported, although relationships between cis-women were sometimes strengthened by shared experiences of menstrual bleeding. Included studies reflected a broad range of disciplines and epistemologies. Many aimed to understand the constructed meanings of menstruation, but few were explicitly designed to inform policy or practice. Few studies focused on socioeconomically disadvantaged groups relevant to new policy efforts. Conclusions We developed an integrated model of menstrual experience in HICs which can be used to inform research, policy and practice decisions by emphasising the pathways through which positive and negative menstrual experiences manifest. Review protocol registration The review protocol registration is PROSPERO: CRD42019157618.


Methods and findings
Primary, qualitative studies capturing experiences of menstruation in HICs were eligible for inclusion. Systematic database and hand searching identified 11485 records. Following screening and quality appraisal using the EPPI-Centre checklist, 104 studies (120 publications) detailing the menstrual experiences of over 3800 individuals across sixteen countries were included. We used the integrated model of menstrual experiences developed from studies in low-and middle-income countries (LMICs) as a starting framework and deductively and inductively identified antecedents contributing to menstrual experiences; menstrual experiences themselves and impacts of menstrual experiences. Included studies described consistent themes and relationships that fit well with the LMIC integrated model, with modifications to themes and model pathways identified through our analysis. The socio-cultural context heavily shaped menstrual experiences, manifesting in strict behavioural expectations to conceal menstruation and limiting the provision of menstrual materials. Resource limitations contributed to negative experiences, where dissatisfaction with menstrual practices and management environments were expressed along with feelings of disgust if participants felt they failed to manage their menstruation in a discrete, hygienic

Introduction
At any given moment approximately 10% of the global population is experiencing their menstrual period [1]. Although menstruation has historically been under-researched [2], there is growing attention to its importance in achieving health, education and gender equality for all [3], including through the recent publication of the definition of menstrual heath as "a state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity, in relation to the menstrual cycle" [pg. 2,4]. In high income countries (HICs), there have been increasing efforts to understand and address menstrual disorders and pain [2], as well as the links between these and negative consequences for employment and education [5]. There is also growing anecdotal evidence that many people who menstruate do not have access to menstrual materials due to financial constraints [referred to as 'period poverty', 6], with reports that adolescents around the world are missing school due to a lack of access to menstrual materials [7,8] and those experiencing homelessness are using makeshift menstrual materials such as toilet paper [9,10]. There has been a consequent overwhelming policy response to provide free menstrual materials. For example, in Scotland, free menstrual materials will soon be available for all who want them [11] and in Victoria, Australia, it was announced in 2019 that all government schools will provide free menstrual pads [12]. These multi-million-dollar programmes have rarely been based on robust research, even though several decades of research from a variety of social science disciplines have highlighted the negative constructions of menstruation throughout society, and feminist campaigners have conceptualised the issue as one of gender-based injustice [13].
In 2019 the UK Government announced its campaign to end period poverty and menstrual shame nationally by 2025 and globally by 2030. To do so they established a taskforce of public sector, private sector, not-for-profit and academic institutions and individuals [14]. This initiative and growing pressure for other HIC governments to act has highlighted the need for more evidence to inform policy development and the opportunity to learn from the rapidly growing body of research and advocacy work on this issue in low-and middle-income countries (LMICs). Population health research across LMIC settings has elucidated a wide range of contributors to menstrual experiences and impacts on health and well-being through a large body of qualitative research. In 2019, this work was brought together through a systematic review and qualitative evidence synthesis which developed an integrated model of menstrual experiences in LMICs [15]. This model has served as a useful framework for understanding menstrual health in LMICs and has helped to inform subsequent research and practice approaches. It is unclear the extent to which this model is applicable in HICs.
To inform the growing policy attention to support people who menstruate in HICs, through this review we identified and synthesised the existing research on menstrual experiences in these countries. We aimed to; 1) collate the existing body of qualitative research on menstrual experiences in HICs and appraise its quality; 2) synthesise this evidence base and develop a model of menstrual experience relevant to HICs, to understand contributing factors, menstrual experiences themselves and the impacts of menstrual experiences on the lives of people who menstruate; and 3) compare findings to the integrated model of menstrual experience developed based on studies in LMICs, in light of differences in the study populations and research topics.

Search strategy and eligibility
The search strategy was designed to capture all qualitative studies, or mixed method studies that included qualitative methods, reporting on experiences of menstruation (Table 1). Searching was undertaken in 9 databases in July 2019 and updated in November 2020 (Applied Social Science Index and Abstracts, Cumulative Index of Nursing and Allied Health Literature (CINAHL), ProQuest Dissertation and theses, Embase, Global Health, MEDLINE, OpenGrey, PsycINFO, Sociological abstracts) (Fig 1).
To supplement database searches, in September 2019 a list of menstrual health organisations and individuals conducting work in HICs was compiled through their registration as a partner of Menstrual Hygiene Day (https://menstrualhygieneday.org/get-involved/partnership/) or a member of the Menstrual Health Hub (https://mhhub.org/community/global-mh-registry/). Search 2: Experience (social behavior or experience or comprehension or knowledge or comprehen � or attitud � or practice � or experienc � or perception � or understand � or challenge � or barrier or facilitat � or impact or affect or effect).ab,kw,ti.
without an accompanying full paper); 5) did not include description of the methodology for data collection (i.e., the reliability of the study could not be assessed). Full text screening was undertaken by DJB. 120 publications describing 104 studies were eligible for inclusion (Fig 1).

Study quality appraisal
Study quality was appraised using the EPPI-Centre checklist [18], developed for assessing the reliability of qualitative research based on rigor in sampling, data collection, analysis and reporting, and the usefulness of the study according to its breadth and depth, the extent to which it privileges the perspectives of those most crucial to the review, in this case, those who menstruate, and the extent to which it details results relevant to the review question. Where studies used mixed methods, we appraised the quality based only on the qualitative data collection methods, analysis and reporting. Two authors (DJB, JH) independently appraised then discussed the quality of a random 10% of studies, to calibrate quality appraisal. DJB appraised the remaining studies, with input from JH on any difficult cases. Study quality ratings and justifications are detailed in S1 Table.

Data analysis
We used a combination of line-by-line coding and thematic network mapping to identify overarching themes and develop our final synthesis [19]. The model of menstrual experience developed through synthesis of studies in LMICs [15] served as the preliminary framework and starting point for deductive and inductive identification of themes. Aligned with the LMIC review, we sought to go beyond description and interpret findings across studies to extend our conceptual understanding of menstrual experiences [20]. Studies contributed parts to an integrated scheme, modelling menstrual experience in HICs [21].
Analysis was undertaken following 6 steps: 1. DJB familiarised herself with the included studies; 2. Using a framework approach, DJB coded the study results, quotations from those who menstruate and author interpretations, in studies of high and medium trustworthiness, in NVivo 12 [22]. Coding was deductive against the themes identified in Hennegan's review of menstrual experiences in LMICs [15], with new themes coded inductively to develop a draft coding template. Examples of a) antecedents to menstrual experiences, b) experiences related to menstrual bleeding and c) impacts on the lives of people who menstruate were coded; 3. DJB constantly compared relationships between antecedents, experiences and impact themes in high and medium trustworthiness studies and coded these relationships in NVivo 12. Relationships were considered saturated where they were evident in at least five studies, and a preliminary integrated model of menstrual experiences in HICs was developed; 4. For validation, two other authors (EW, JH) coded 15% of studies each (i.e., 30% of studies were coded in total). Using the same approach as DJB, they deductively coded studies against the framework of themes from the review of studies in LMICs and inductively identified new codes independently, that is, without having reviewed DJB's coding template. DJB reviewed co-author coding and it was consistent with the coding template; 5. The integrated model was shared with all co-authors for discussion, followed by repeated mappings until all agreed that the model developed had the greatest explanatory power; 6. DJB coded studies of low trustworthiness and assessed their fit with the final themes and integrated model. Low-quality studies supported the primary analysis, and no new constructs emerged (this is akin to the 'sensitivity analysis' common in systematic reviews of qualitative research, in which themes are checked to see if they rely on low-quality studies alone [19]).
The final model and themes are contrasted against findings from the review of LMIC studies in the Discussion, facilitated by the process of coding against these themes during our analysis.

Positionality
The authors are women who menstruate and live in HICs. Throughout the study they employed self-critical epistemological awareness [23], considering how their own experiences influence their interpretation of findings, privileging the voices of study participants and attempting to set aside their own biases to maximise rigour in the analysis.
Prior to beginning this study, the authors had all undertaken research on menstrual health in LMIC contexts. Most of the publications included in this review were unknown to them, allowing the model to be developed from the experiences of the study participants rather than previous work the authors were familiar with.

A note on inclusivity
Historically the terms 'girl', 'woman' and 'female' have been used interchangeably to denote individuals who menstruate. This ignores the differences between biological sex and self-identified genders. Not all people identifying as women and girls menstruate, and not everyone who menstruates identifies as a woman or girl. Although most included studies used the language of girls and women exclusively, the genders of participants may have been assumed because the participants were people who menstruate. We reviewed five studies (all published since 2016) that specifically recruited participants who menstruate but do not identify as a woman or girl, here referred to as non-binary or transgender people who menstruate [24][25][26][27][28]. We thus use gender neutral pronouns throughout the paper, except in cases where the finding is specifically linked to gender identity or is only relevant to cis-gendered, non-binary or transgender menstruators, in which cases we use the gendered terms and pronouns found in the original publications. Table 2 reports study characteristics and the overall trustworthiness and relevance ratings from quality appraisal. The included studies involved over 3800 participants. Eighty-three studies included women (18 years of age and older), 24 studies included girls (below 18 years of age), and five studies included adult menstruators who identified as transgender or nonbinary (18 years of age and older). Included studies spanned many decades, and frequently included retrospective reports of menarche experiences from many years prior to data collection. Table 2 provides an estimate of the time period when participants reached menarche based on their age and the date of the study. In 9 studies participants had reached menarche during the early 20 th Century (C) (defined here as 1900-1949), the mid-20 th C (defined here as  in 46 studies, the late 20 th C (defined here as 1980-1999) in 61 studies and the early 21 st C (defined here as after 2000) in 44 studies. We could not determine the approximate timespan of menarche for 22 studies. Twenty included studies specifically recruited Decade of data collection is an estimate where publications were unclear. 5 Indicates an intervention study. 6 Indicates a study where participants with menstrual disorders were specifically recruited. 7 Indicates a study where those who menstruate but identify as transgender or non-binary were specifically recruited. 8 Indicates a study where low-income participants were specifically recruited. https://doi.org/10.1371/journal.pone.0255001.t002

Study characteristics
participants experiencing endometriosis, dysmenorrhea and/or menorrhagia. Six studies specifically recruited low-income status participants. North America (47 studies) and Europe (42 studies) were represented far more than other regions (Oceania = 11 studies, Asia = 1 study, Middle East = 1 study, global/online = 2 studies). Eighty-six studies collected data using individual interviews (85 verbally, 1 written), 23 used group interviews (including focus group discussions), seven written narratives, seven written questionnaires, two direct observations, two written diaries and one creative writing. Four studies involved interventions which aimed to improve experiences of menstruation. Included studies were situated within the disciplines of population health, sociology or gender studies. Most approached data collection and analysis through a social constructivist lens, and sought to understand menstrual experience through an extensively detailed understanding of each participant's lived experience through the use of interpretive phenomenological analysis [29], grounded theory [30] or thematic analysis [31].

Study quality
Study quality was varied, with 36 studies rated as high, 48 as medium, and 20 as low trustworthiness (detailed in S1 Table). Lower-quality studies were characterised by small, convenience samples and limited details on data collection and analysis.
Twenty studies were rated as highly relevant, 59 as medium, and 25 as low. Most studies rated as high relevance had findings which were reflective of a large proportion of the population (e.g., menstruators in HICs), whereas studies rated as medium relevance were more likely to be specific to the experiences of sub-populations (e.g., menstruators with an intellectual disability) or during specific experiences (e.g., at menarche). Studies rated as low relevance did not clearly incorporate or represent the voices of those who menstruate in study design and/or findings.  Table 3 details which studies contributed to each theme. Boxes 1-3 provide quotations which support the findings for each theme.
Study participants often stated that they hid evidence of menstruation, including the physical symptoms and pain management associated with it, because they believed this was socially expected of them, even where they had not been specifically told to do so [8, 32, 38, 41, 47, 50, 53-56, 58, 60, 64, 67, 75-81, 87, 88, 93-96, 106, 108-110, 112, 116-122, 128, 129, 143]. Where their menstruation did become obvious to others this resulted in strong negative emotions, feeling distressed and embarrassed. Participants generally did not speak about menstruation (their own or others') publicly, particularly not with men and boys, as they considered this to  Washing/drying materials, n = 1 study [50] Perceptions of physical environment (n = 18 studies) n = 8 studies [26,28,47,51,111,122,126,132] n = 9 studies [24,25,54,80,81,88,115,117,138] n = 1 study [10] (Continued ) Analgesic or anti-inflammatory medicines, n = 2 studies [64,129] Sex, n = 2 studies [33,73] Sex, n = 1 study [56] Sex, n = 1 study [41] IMPACTS (Continued ) There were a few examples in the studies from participants who reached menarche from the late 20 th C onwards of insisting that this secrecy should be challenged, for example, displaying menstrual materials publicly [pg. 54,81] or insisting on menstrual discussions with boys and men who did not want to engage [pg. 110, 81, pg. 8, 110]. However, it was also noted by authors that "women who began menstruating in the 1980s and 1990s told me that they felt no shame or discomfort about their monthly cycles. They were dubious as to whether menstrual taboos still operated in Australia. Yet their memories of managing bleeding reveal a continuing expectation that menstruation be masked as much as possible" [pg. 244, 117] and "although some participants who began menstruating in the late 20 th and early 21 st Cs specifically questioned this norm "as they feel that menstruation is a natural phenomenon that all women experience and should therefore not have to be concealed," they, "still want to hide their periods, keep them private, and choose not to confront the social norm"" [pg. 608,47].

Relationships
"A wonderful secret that they [boys] would never know about and never experience" [pg. 138,32] "I want to talk to my butch friends about my period, but even though I'm ok with it, I'm afraid it will be triggering for them so I don't, which can feel isolating" [pg. 1246, 24]. menstruation [32,38,56,63,65,70,95,104,106,109,110,119]. Several studies included participants stating that they appreciated the social support they received during adolescence from other family members, particularly grandmothers, sisters and aunts [65,71,99,106,110,119,121,122,127,135,144], and sometimes brothers and fathers [32,43,54,61,71]. A few participants stated that they had received inadequate support from their fathers [32,56,61,95,121].
Friends and colleagues were often mentioned as assisting menstruators with concealing and containing menstruation across the lifespan through providing menstrual materials, notifying one another of stains, or helping hide menstrual practices [24,37,43,47,48,56,63,75,78,88,94,95,112,115,118,122,124,138]. Some participants, particularly those with menstrual disorders or discomfort, reported having emotionally and/or practically supportive work colleagues, who allowed them flexibility in the workplace. These were often women [47,80,112,114,115,119,122,124,129,138], although some participants specifically mentioned supportive men [80,118,124,129]. Several participants indicated that other women became frustrated with them when they were unable to fulfil social or work duties due to debilitating pain or fatigue, often implying that menstrual discomforts were a 'normal' part of life and should not impact on participation or work quality [8,40,61,71,76,80,103,119,122,128].
In several studies participants with menstrual disorders (e.g., endometriosis, menorrhagia, dysmenorrhea) had previously consulted healthcare workers and had their concerns dismissed [26,40,55,57,58,61,71,75,85,99,101,103,111,119]. Where healthcare workers did acknowledge the experience of pain and/or heavy bleeding they often expressed that menstrual symptoms were just a normal part of being a woman, or that the patient must have "a very low pain threshold" [pg. 45,71]. They either could not do anything for them or recommended painkillers [40,55,57,58,61,71,80,81,85,111,112,119,122,137]. Less frequently participants spoke about the relief of a positive interaction with a healthcare professional (generally following many negative experiences) where they "felt heard" [pg. 234, 40] and were sometimes assisted in developing pain management strategies they considered effective [40,51,55,59,61,77,81,85,99,111,122], leading to improved impacts on mental burden, relationships and participation. A few participants noted that their intimate partner was supportive of them when they were experiencing menstrual pain [56,61,81,119,122].
Participants who had reached menarche in the early-mid 20 th C often indicated that they had not known what menstruation was at the time of their menarche [8, 38, 42, 56, 60, 65, 69, 72, 81, 87, 89, 93-97, 102, 109, 110, 116, 119, 120, 135]; in most cases this lack of knowledge led to distress when first bleeding was discovered. In the early 20 th C, adolescent participants were often instructed not to swim in cold water or wet their hair because they were incorrectly advised that it was physically dangerous to do so during menstrual bleeding [45,60,63,65,71,81,95].
Across the timespan of studies there was limited discussion of being taught about menstruation in a formal school environment; some participants reported that at menarche their mother explained some of the biological and reproductive aspects of menstruation to them [32,38,42,56,63,64,72,81,95,96,106,109,116,119,120,135]. Many participants were educated on the physical management of menstruation by their mothers, at the time of their menarche [32, 38, 43, 63, 88, 93-96, 106, 116, 127]. However, several noted that the information their mother gave them was inadequate and they would have appreciated more instruction [32,36,38,47,50,56,91,94,95,104,110,119,135,138].
Participants often selected the material they used based on absorbance or how long it could be used for without needing to change [57,59,81,114,119,120,122,123,126,128]. Participants with heavy bleeding particularly needed to plan their menstrual practices, often through wearing tampons and pads, or multiple pads, at the same time [53,57,61,69,81,112,119,120,122,123]. Across the timespan of studies many participants expressed discomfort at using pads, describing them as hot and abrasive [38,56,59,71,72,81,92,95,108,117]. Some nonbinary or trans-men who menstruate preferred not to use tampons or menstrual cups because the insertion of these products contributed to their gender dysphoria [25,27,28].
The choice of disposal practices was normally based on whether it would conceal the users' menstrual status [24,25,28,41,42,47,50,51,81,114,116,117,120,132], and where disposal did not conceal menstrual status the participant sometimes felt intense shame [38,88,112,122]. Washing reusable cloths was discussed in some publications where participants reached menarche in the early 20 th C, and it was repeatedly noted that this "burdensome" and "distasteful" [pg. 238, 117] chore must be done discreetly, even though there was often no way of doing so, for example, where washed cloths needed to hang on shared clotheslines [81,93,94,106,108,116,117]. Across the timespan of studies, participants often tried to hide menstrual materials when purchasing them and described embarrassment when the cashier was a man [10,24,37,54,56,67,78,79,81,82,93,116,119,120]. Participants who could not afford to purchase menstrual material often felt embarrassed at having to obtain them from friends or nonprofit organisations such as shelters [9,10,37,48].
Several studies specifically discussed participants' perceptions of tampon use. Many participants who reached menarche in the mid-20 th C were told by their mothers that they could, or should, not use tampons [32,49,50,63,81,106,110,121], at menarche they were either expressly forbidden without grounds, or told that tampon use would result in them having 'lost' their virginity or contribute to them engaging in sexual activity. Some participants believed this when they were told, but appeared to have changed their mind by the time they engaged in the studies (data collected from the late 20 th C onwards) [56,81,116,117]. Many participants who used tampons spoke of them as being "liberating" or "emancipatory" [pg. 242, 117] as they were easy to conceal and allowed them to partake in activities which they could not previously [49,50,56,81,106,117]. Where participants reached menarche in the mid-20 th C onwards there was concern around the risk of toxic shock syndrome when using tampons, sometimes leading to a reluctance to try them [36,56,69,80,81,127].
Negative emotional responses. Participants described a variety of negative emotional responses as part of their menstrual experience. Hennegan et al.'s review of LMIC studies identified 'shame and distress' as a theme and part of the integrated model, with positive emotions described as divergent cases under this theme [15]. In contrast, studies included in our review reported a wider array of emotional reactions to menstruation. Less intense negative responses were often described, such as feeling menstruation was inconvenient or bothersome. Further, in inductively coding study findings we identified different antecedents and impacts of negative and positive emotional responses and so separated these to capture experiences reported in HIC study populations.
Confidence to engage in activities during menstruation. A number of studies included participants who spoke of their confidence (or lack of) to engage in activities during menstruation [28,33,38,40,47,56,73,80,81,106,108,112,114,[117][118][119]122]. Often those who had begun using tampons or a menstrual cup particularly mentioned how this gave them the confidence to engage in more activities [28,38,56,81,114,117]. Conversely, some participants who were ashamed of their menstrual status or experienced painful symptoms lacked the confidence to participate in activities during their period [38,47,56,108,119].
Participation. Participation in a variety of activities differed over time and between individual participants. Sometimes respondents did not participate in activities because they lacked the confidence that their menstrual practices would conceal their menstrual status, occasionally due to a past, embarrassing experience of failing to contain menstrual fluid and conceal physical symptoms [40,48,49,55,57,58,61,71,72,80,96,98,105,112,119,122,129,134,135,137]. Other times, particularly in studies where participants reached menarche from the mid-20 th C onwards, respondents were forced by mothers to go to school and participate in other activities during menstruation, even if they did not want to [8,63,64,109,110,128]. Sometimes individuals chose to participate in activities despite menstruation, just "'getting on' with life" [pg. 1337, 53], particularly from the late 20 th C onwards [38,40,47,50,53,56,110]. However, many who participated in activities would have preferred not to, but did so due to the behavioural expectation that menstruation should not stop them [8,40,47,53,56,58,61,63,64,77,80,98,100,105,107,109,112,122,128,138]. During participation, these individuals often experienced distress and pain [8,40,53,56,58,61,63,64,80,100,105,109]. Employment was often disrupted by menstruation, particularly for those experiencing menstrual disorders, including not going to work, leaving work, or having their quality of work impacted by the physical symptoms and/or behavioural expectations of menstruation, including hiding their menstrual status [8, 34, 40, 47, 53, 55-58, 61, 64, 71, 76, 80, 103, 105, 112, 114, 119, 122, 129]. Those who were able to be more flexible (e.g., those in more senior positions) managed their tasks and schedules to reduce the impact of menstruation on their employment [80,105,111,112,114,119,122]. Others went to work despite menstrual symptoms for fear of losing their job [53,56,61,76,80,108,112,129].

Discussion
The large number of studies of high or medium level trustworthiness and relevance enabled us to prepare an evidence synthesis and develop an integrated model which adequately captures the experiences of many of those who have menstruated in HICs over the past century, with some insights for specific sub-populations where multiple studies have been conducted. Across the timespan of studies and the multiple geographical contexts, the lived experiences of people who menstruate reflected consistent themes and relationships. Participants commonly expressed many negative experiences and detrimental impacts linked to menstruation-much more frequently than positive experiences and beneficial impacts. Although we should not conclude that the majority of those who menstruate in HICs are negatively affected, as often participants in these studies were recruited specifically to discuss negative experiences, it is clear that many people who menstruate within HICs have experienced negative wellbeing related to menstruation. The integrated model highlights particular themes and pathways which could be addressed in future to improve menstrual health.

Some common pathways of menstrual experience in HICs
Socio-cultural context, particularly the stigmatisation of menstruation and gender norms related to managing menstruation, often manifested in behavioural expectations being placed on those who menstruate, particularly to conceal menstrual status, often referred to as 'menstrual etiquette' [146]. Difficulties in abiding by expectations to contain menstrual fluid and conceal menstrual status often resulted in negative experiences, including distress and bother, as well as increased mental burden and consequences for participation and intimate relationships. Over the timespan of studies reviewed there was an increase in satisfaction with the menstrual materials on offer but concerns around adequately concealing menstrual status persisted.
Social support influenced the amount of knowledge participants had regarding the biology and practical management of menstruation. Where cis-women and girls felt they had adequate social support and knowledge, this sometimes led to happiness and improved relationships with other cis-women and girls, particularly at menarche. However, it was more common for participants to feel they received inadequate social support or knowledge about menstrual health and hygiene, which led to negative experiences, including shame and a lack of confidence to engage in activities, impacting participation and increasing mental burden. Knowledge of menstruation increased over time in the reviewed studies, reducing the negativity associated with menarche.
Resource limitations, particularly a lack of access to menstrual materials and facilities, were sometimes driven by the socio-cultural context itself, such as the lack of policy and public attention given to the menstrual health of low-income individuals or those who identify as non-binary or trans-men. Resource limitations contributed to negative experiences, including feelings of personal disgust at participants' own inability to manage their menstruation hygienically and in their preferred way. Such experiences often led to significant mental burden and a reduced participation in activities. The resource limitation theme and its implications were heavily informed by very recent, exploratory studies [10,37,48,62,65,126,132]. There is thus far insufficient evidence capturing the unmet menstrual health needs of marginalised and socioeconomically disadvantaged populations. Most studies focused on higher-income, adult groups and limited studies were identified responding to current policy priorities around inadequate access to products and supportive infrastructure for menstrual health, and adolescent menstrual health.
Individual menstrual factors such as pain, fatigue and gastrological and neurological symptoms were commonly associated with negative experiences, and led to increased mental burden, as well as detrimental impacts on participation and relationships. Participants who experienced irregular periods suffered particularly high mental burden from the constant need to be 'prepared' in case menstrual bleeding began unexpectedly. Those with menstrual disorders expended significant energy hiding their symptoms from employers and/or feeling guilty about letting colleagues and family members down. However, where healthcare workers were supportive and pain management effective, some participants did feel relief and reduced mental burden, and saw an improvement in their participation and relationships.

Comparison to LMIC model
In both the HIC and LMIC bodies of evidence the socio-cultural context influenced behavioural expectations, impacting menstrual experiences and subsequent consequences for the lives of participants. The influence of menstrual stigma on menstrual experience and wellbeing was remarkably similar. As Hennegan et al. stated "Women and girls internalised menstrual restrictions and stigma and sought to regulate their behaviour accordingly. This impacted confidence to engage in other activities during menstruation and added to experiences of shame because a failure to hide menses was viewed as a personal failure to maintain feminine standards or menstrual etiquette." [pg. 22,15]. This could be written verbatim with reference to the HIC model. The power of social support sources including mothers, friends, and healthcare workers to positively or negatively influence the experience of menstruation, emotional responses experienced and participation in daily life also echoed across both syntheses, as did the role of knowledge about menstruation and its management in supporting confidence, positive experiences and wellbeing.
Less emphasis in HIC studies was placed on resource deficits and the economic and physical environment than in LMICs. In LMICs, poverty and difficulty accessing resources for menstrual management were a significant focus of studies and a salient burden for participants. This difference likely reflects the relative resource and access to infrastructure across these participant groups, although it should be noted that in more recent HIC studies where these deficits have been explored, similar concerns to LMIC participants have been raised around accessing acceptable, reliable, and comfortable menstrual materials, along with supportive spaces for changing and disposing of them [10,37,48,62,65,126,132].
In contrast to the LMIC studies reviewed, few HIC studies described a lack of confidence to manage menstrual bleeding. This may reflect that the HIC review included primarily studies of adult women's experiences, compared to the focus on adolescent populations in LMICs, as well as the availability of supportive resources and infrastructure. However, varied confidence to engage in other activities during menstruation, and an enduring emphasis on concealment, were clearly reflected in both bodies of evidence and contributed to negative impacts on mental burden and participation.
Many studies included in the HIC review emphasised experiences of needing to endure discomfort or pain to maintain participation in work or other activities during menstruation. This appeared in contrast to studies from LMICs which more commonly highlighted consequences in terms of missed school or social participation. Notably, more recent studies from LMIC settings with adolescent girls and adult women have reported pressure to carry on with expected activities while concealing menstruation [147,148]. It is likely that this experience is shaped by the evolving sociocultural context and experience at different ages.
Impacts of menstrual experiences on physical health, specifically the reproductive tract infections and irritation noted in LMICs, were not observed in the HIC literature. The absence of such discussions may be due to more advanced health infrastructure, and resource availability.
Differences between the broadly similar HIC and LMIC models must be interpreted in light of contextual differences as well as differences in the bodies of research reviewed, including study aims and participant recruitment. Studies included in the LMIC review tended towards a post-positivist epistemology, recruited low-income participants, and were designed with the intention of providing practical and policy recommendations related to menstrual health and resource deprivation. Studies from HICs tended to focus on in-depth, social constructivist investigations of menstrual experiences, without the intention of developing practical recommendations. We suggest that insights gained from comparing the two models and interrogating the assumptions shaping research and discourse in the different settings could strengthen global menstrual health and hygiene research, practice, and policy.

Strengths and limitations
Our comprehensive searching strategy and efforts to identify relevant grey literature are a strength of this review. Qualitative studies of particular menstrual disorders directly related to menstrual bleeding were included, however we were limited in our analysis of how these specifically manifested in comparison to the general population [e.g., heavy menstrual bleeding, 149, endometriosis, 150]. In addition, for practical reasons and to enable a clear comparison to the LMIC study, we limited our review to menstrual bleeding experiences, but recognise the importance of researchers examining individual experiences during other parts of the menstrual cycle.
One intention of this review was to contribute to current policy debates and actions aimed at addressing period poverty in HICs, but we were limited in the conclusions that could be drawn as, until very recently, most studies have focused on higher income populations. Studies tended to have been conducted in Europe or North America, although our requirement that records be available in English likely contributed to this limitation. Inclusion of studies in other languages would strengthen our model and its broader applicability.

Implications and conclusions
Our integrated model is the first to map experiences of menstruation in HICs. The model can be used as a framework for understanding the factors to be considered when seeking to improve menstrual experiences and menstrual health. For example, the model suggests that approaches to reduce stigma, combat restrictive behavioural expectations and improve knowledge, social support and pain management may represent key levers for improving menstrual health. New research conducted in HICs can be informed by this work, with the model providing guidance on important themes, relationships and population groups for further exploration.  Table. Quality appraisal of included studies. References in black boxes indicate they are from a study with multiple publications included in this review (publications from the same study are grouped together in Table 2). Quality is assessed at the publication level here and at the study level for analysis. Adapted from the EPPI-Centre Checklist detailed in Rees, R., Oliver, K., Woodman, J., Thomas, J. (2009) Children's views about obesity, body size, shape and weight: A systematic review. EPPI-Centre, London:UK [18]. (PDF)