Characteristics of Menstrual Cycles, Prevalence of Menstrual Disorders in Young Women and Their Relationship to Hormonal Contraceptive Use.

Noelia Sánchez‐Millán: conceptualization, investigation, data curation, writing – original draft, wrting – review and editing. Sergio Martínez‐Vázquez: conceptualization, software, data curation, investigation, supervision, writing – original draft, writing – review and editing, project administration. Ana Ballesta‐Castillejos: writing – original draft, writing – review, investigation. Juan Miguel Martínez‐Galiano: conceptualization, writing – original draft, writing – review and editing, investigation, methodology, resources. Sandra Martínez‐Rodríguez: conceptualization, data curation, investigation, writing – review and editing. Antonio Hernández‐Martínez: conceptualization, investigation, formal analysis, resources, software, methodology, writing – review and editing.

Approval was obtained from the University of Jaén Ethics Committee with code MAR.23/3.PRY. All participants signed the informed consent form.

The authors received no specific funding for this work.

A cross‐sectional observational study was carried out with young university women from the provinces of Jaén, Ciudad Real, and Albacete during 2024. The inclusion criteria were women between 18 and 25 years of age. The only exclusion criterion was failure to complete the questions regarding menstrual parameters for the previous 6 months due to lack of recall. The sample size estimate considered a prevalence of heavy bleeding that could be as high as 20% in young women [ 17 ]. Considering a 95% confidence level and an absolute error of 4%, a minimum sample size of 385 women was required. For the collection of information, a pilot online questionnaire (Supplementary Material) was developed and distributed via e‐mail to female students in the university campuses located in Ciudad Real, Albacete, and Jaén through the collaboration of the faculty staff, who were responsible for disseminating the questionnaire. The teaching staff provided information about the aim of the study, and women who expressed their wish to participate were given a link to complete the questionnaire. An instant messaging group was created where women could ask any questions they had. This questionnaire consisted of 26 items on sociodemographic variables, clinical variables, contraceptive methods, and the characteristics of the menstrual cycle in the last 6 months. The questionnaire was developed and piloted in a group of 10 young women with different sociodemographic characteristics. As dependent variables, the different menstrual patterns (frequency, regularity, duration, and volume) [ 18 , 19 ]. Normal frequency is defined as the onset of menstrual bleeding every 24–38 days. Menstrual regularity is defined by the variation in cycle length from cycle to cycle. While slight variations in cycle length are normal, a cycle is considered regular if the difference between the shortest and longest cycle lengths, for those between the ages of 18 and 25, is less than or equal to 9 days. A cycle is considered irregular if the cycle length varies by 10 days or more [ 20 ]. In terms of cycle length, it is considered normal when the number of days of bleeding in a single menstrual period is less than or equal to 8 days, therefore bleeding > 8 days is considered prolonged, there is no consensus on the lower limit of normal menstrual duration [ 21 ]; therefore, it was not included. Regarding volume, a menstrual blood loss of less than or equal to 80 mL per cycle was considered normal [ 18 , 19 ]. For this parameter, variables related to the frequency of changing tampons and pads were taken into account [ 22 ]. In clinical practice, it is difficult to objectively determine the amount of menstrual loss, so the diagnosis is based on information provided by women, that is, self‐reported. As independent variables, the following sociodemographic and clinical variables were included: age, height, weight, BMI, level of physical activity, smoking, alcohol consumption, age at menarche, presence of polycystic ovary syndrome (PCOS), endometriosis, or any other gynecological pathology, as well as the use of contraceptive methods such as condoms, HC, or natural methods. First, the data were analyzed descriptively using absolute frequencies and their respective percentages for categorical variables and mean with standard deviation (SD) and percentiles to describe quantitative variables. The bivariate relationship between HC use and menstrual patterns (average cycle length, cycle duration, and menstrual bleeding duration) was then studied using mean differences (MD) and including in a multivariate analysis all potential confounders by means of the adjusted mean difference (aMD) with their respective 95% confidence intervals (95% CI). Bivariate and multivariate analysis was also performed to analyze the relationship between HC use and the parameters used in the literature to define normal menstrual bleeding: frequency, irregularity, duration, and volume of bleeding. Crude odds ratios (OR) and adjusted odds ratios (aOR) were estimated with their respective 95% confidence intervals (95% CI). Seven factors were included in the multivariate analysis that, according to the literature, were associated with cycle disturbances: age, BMI, endometriosis, polycystic ovarian syndrome, alcohol consumption, physical exercise, and tobacco use. Approval was obtained from the University of Jaén Ethics Committee with the code MAR.23/3.PRY. All participants signed the informed consent form.

A total of 404 women participated, with a mean age of 20.7 years (SD = 1.91 years). Mean height and weight were 163.4 cm (SD = 6.28 cm) and 60.4 kg (SD = 11.14 kg), respectively. Approximately 24.5% (99) of participants did not perform any physical activity, while 13.1% (53) performed physical exercise more than 300 min per week. Approximately 15.1% (61) did not consume any alcohol compared to 13.6% (55) who consumed alcohol occasionally and on weekends. As for the use of hormonal contraception, 73.3% (296) reported not using this type of contraceptive method. Finally, the presence of endometriosis was present in 3.2% (13) of the cases of which 15.4% (2) were taking HC, PCOS was present in 14.4% (58) of which 60.3% were taking HC, and 5.2% (21) reported having another gynecological pathology. The use of IUDs, implants, or medroxyprogesterone injections has not been reported. The remaining characteristics are shown in Table  1 . Table  2 shows a description of the different contraceptive methods. Sample characteristics. Abbreviations: M, mean; SD, standard deviation. Hormonal contraception. Regarding the characteristics of the menstrual cycle from a quantitative point of view, the average length of the menstrual cycle was a mean of 29.0 days (SD = 4.28 days), a median of 28.5 days with a 90th percentile of 35.0 days (Table  3 ). For the duration of bleeding in a single menstrual cycle, the mean was 5.1 days (SD = 1.20 days), and the median was 5.0 days with a 90th percentile of 7.0 days (Table  3 ). For the longest cycle length, the mean was 33.8 days (SD = 8.64 days), and a median of 32 days with a 90th percentile of 50 days. For the shortest cycle length, the mean was 26.0 days (SD = 3.94 days), and the median was 27 days, with 30 days at the 90th percentile. On the other hand, the age at menarche or age at first menstruation was 12.1 years (SD = 1.47 years), with a median of 12 years and a 90th percentile of 15 years (Table  3 ). Characteristics of menstrual patterns. Abbreviations: M, mean; P, percentile. Different values. In terms of menstrual patterns, 3% (12) reported prolonged duration of menstrual bleeding, that is, a duration of menstrual bleeding in the same cycle > 8 days. On the other hand, 19.3% (78) reported frequent cycles compared to 11.1% (45) who reported having infrequent cycles, the normal frequency of the menstrual cycle is that which occurs between 24 and 38 days. Regarding the regularity of the menstrual cycle, 25% (101) reported irregular menstrual cycles; finally, in terms of the volume of bleeding, 28% (113) had to change their tampon or pad less than or equal to 3 h, 17.1% (67) needed to change at night, 11.9% (48) were anemic, and 10.1% (41) needed to take iron supplements (Table  4 ). Menstrual abnormalities. The adjusted mean difference in average menstrual cycle length between the HC‐taking and non‐HC groups was 2.95 days (95% CI: 1.94–3.97). As for the longest menstrual cycle length, the aMD between those taking HC and those not taking HC was 4.91 days (95% CI: 2.91–6.90). Finally, the aMD for the duration of menstrual bleeding in the same cycle between the HC‐taking group and those not taking HC was 0.72 days (95% CI: 0.44–0.99) (Table  5 ). Menstrual patterns and hormonal contraception. Bivariate and multivariate analysis. Note: Bold: statistically significant differences. Abbreviations: aMD, mean difference adjusted for age; BMI, endometriosis, polycystic ovary syndrome, alcohol consumption, exercise, and tobacco; MD, mean difference. A bivariate and multivariate analysis was performed between HC use and menstrual cycle alterations. Regarding the presence of irregular cycle, HC use resulted in a reduction of this alteration with an aOR of 0.28 (95% CI: 0.14–0.56), the probability of infrequent bleeding or bleeding > 35 days was also reduced with an aOR of 0.18 (95% CI: 0.06–0.57), as well as the volume of bleeding with an aOR of 0.47 (0.47; 95% CI: 0.26–0.85). No statistically significant differences were observed for the other outcomes assessed (Table  6 ). Menstrual disturbances and hormonal contraception. Bivariate and multivariate analysis. Note: Bold: statistically significant differences. Abbreviations: aOR, odds ratio adjusted for age; BMI, endometriosis, polycystic ovary syndrome, alcohol consumption, exercise, and tobacco; OR, odds ratio. Finally, if we look at the boxplot graph we can see how the use of HC is associated with more regular and shorter cycles, with fewer extreme variations (Figure  1 ), and in terms of menstrual bleeding in the same cycle we see how the use of hormonal contraception is associated with a shorter and less variable duration of menstrual bleeding (Figure  2 ). Average length of menstrual cycle. Average duration of menstrual bleeding.

As implications for clinical practice, we can highlight that this is one of the few studies that addresses all menstrual disorders in young women and may be very useful for establishing comparisons with other regions and in the near future. Considering the prevalence ratio of menstrual abnormalities (in terms of regularity and excessive bleeding) and its interaction to HC, its crucial to approach the contraception in young women early in their reproductive and sexual health, being treated each one as unique individual and addressing their care based on their individual needs.

The lead author Sergio Martínez Vázquez affirms that this manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned (and, if relevant, registered) have been explained.

Our findings showed that menstrual disorders were present in a large part of the study sample. The most prevalent disorders were irregularity, affecting 25%, and heavy menstrual bleeding, with 28% needing to change their pad/tampon every 3 h and 17.1% also needing to do so at night. Therefore, irregularity and heavy menstrual bleeding occurred in more than 50% of the women studied. HC were among the factors associated with these disorders. It could be stated that the use of HC is associated with less irregularity and less infrequent and heavy menstrual bleeding. The average length of the menstrual cycle averaged 29.0 days and the average duration of menstrual bleeding was 5.1 days. Similar data were reported by Rojas et al. [ 23 ] in their study on menstrual patterns in young Venezuelan women, where they identified an average menstrual cycle length of 28.9 days and the average duration of menstrual bleeding was 4.8 days. We also observed similar data in the study by Carranza et al. [ 24 ] and in a study in southern Spain, where they identified an average menstrual cycle length of 29.8 days and an average duration of bleeding of 4.97 days [ 25 ]. In terms of menstrual abnormalities, we observed a rate of prolonged duration of menstrual bleeding of 3%, and a rate of irregular menstrual cycle of 25%. In addition, we identified that more than 20% have excessive bleeding volume as they need a pad/tampon change every 3 h, and about 17% also need to do so at night. This prevalence is in line with the range found in a systematic review conducted by Pouraliroudbaneh et al., in which they included a total of 55 observational studies; they found a prevalence of heavy menstrual bleeding among young women from 4% to 63% [ 26 ]. In another study, they reported the prevalence of menstrual cycle irregularity to be between 5% and 35.6%, which also agrees with the findings [ 27 ]. However, despite this, we consider that there is a large variability in the prevalences found due to the use of different non‐standardized methodologies for measuring blood loss. In addition, there were also variations in the definition of excessive menstrual bleeding and irregularity because they did not fit the criteria for normality established by the most recent literature. In terms of HC, more than a quarter of women in our study use this type of contraceptive method, with dysmenorrhea or menstrual pain and control of menstrual bleeding being among the most frequent reasons for use. According to the results of the multivariate analysis, it could be stated that the use of HC is associated with a shorter average menstrual cycle length, a reduction in the duration of bleeding days, and a reduction in the volume of bleeding. These results are consistent with a European multicenter study that included women from 12 countries, which stated that menstruation was significantly longer and heavier in women who did not use HC than in those who did [ 6 , 28 ]. Furthermore, our findings suggest that HC use is associated with a reduction in the occurrence of irregular menstrual cycles. These findings are in line with previous studies such as Harlow and Campbell et al. [ 29 ] where it was observed that the use of HC can reduce the amount and duration of menstrual bleeding, and in a systematic review on the use of HC in heavy menstrual bleeding in which they included a total of 8 randomized controlled trials and a total of 802 women, they concluded that the use of oral HC for more than 6 months improved the probability of correction of this alteration from 12% to 77% [ 30 ]. Regarding the limitations of this study, it should be noted that the data were obtained based on a cross‐sectional design and that the participants were selected from a part of the Spanish university population, which implies a higher probability of participation of women with menstrual disorders, being the population with the highest prevalence of this phenomenon; however, the results do not differ from other studies reviewed and analyses adjusting the results for the main factors described in the literature have been used. The diagnosis of menstrual disturbances was self‐reported by the women and could be subject to misinterpretation of some questions. However, we believe this bias may be minimal because the questions asked were simple and the women had an adequate level of education to give a correct answer. Among the strengths of this study is that it was carried out in Spain, where studies on menstrual patterns and disorders in young women are very scarce. The main characteristics of the menstrual cycle have been identified based on the terminology defined by FIGO [ 4 ] to establish the criteria for normality, thus increasing awareness of the importance of using a common terminology to make differential diagnoses between normality and abnormality and to establish treatments without the need for delays. Another important finding is that we have confirmed that the use of hormone treatment improves menstrual cycle dysfunctions. In addition, as menstrual abnormalities occur frequently in young women, this suggests the need for greater awareness, both among professionals and in the general population. The identification of the most frequent abnormalities supports the fact that health professionals must be prepared to offer advice not only on identification but also to explore and advise on methods to reduce this problem. However, further work needs to be carried out in other geographical areas, using standardized measurements and definitions with consistent methodologies to diagnose and treat this common problem without leading to underdiagnosis and delays in treatment.

One in four young women had menstrual abnormalities due to irregularity and excessive menstrual bleeding. On the other hand, women taking HC had a lower incidence of irregular cycles, excessive bleeding volume, and prolonged menstrual cycles.

Menstrual disorders and abnormal uterine bleeding are among the most frequent gynecological consultations among women [ 1 ] and may even affect 3 out of 4 women in childbearing age [ 2 , 3 ]. Abnormal uterine bleeding is a bleeding pattern that is not compatible with the normal parameters of the menstrual cycle (frequency, regularity, duration, and/or volume) [ 4 ]. Excessive cycle disorders (due to their intensity and/or persistence over time) should be highlighted due to both their prevalence, between 22.5% and 35% of childbearing age women and their consequences, which can lead to anemia and even the need for transfusion [ 5 ]. These disorders can have a major impact on women's quality of life and limit their activities of daily living, as well as representing a significant consumption of healthcare resources and an estimated annual cost of over $2000 per woman [ 5 ]. This high cost is mainly attributed to absences from work or school, lower productivity or lower levels of performance, and impacts on social activities. For these reasons, many women choose to take hormonal contraceptives (HC) to reduce these menstrual problems and improve their quality of life [ 6 ]. In Spain, a survey conducted in 2024 by the Spanish Society of Contraception (SEC) estimated that 78.5% of women of childbearing age use some form of contraception, and of these, 25.3% use a hormonal method. This survey also indicates that 29.4% of these women use hormonal contraception as a treatment, specifically 6.8% as a therapy for heavy bleeding [ 7 ]. However, paradoxically, taking HC is also associated with changes in menstrual bleeding and is one of the main motivations for stopping. Although all contraceptives can cause menstrual disorders, these are usually more frequent in preparations that only contain progestogens in their different forms of presentation (pill, implants, IUD, etc.), sometimes even leading to amenorrhea [ 8 ]. In fact, there are even variations in menstruation patterns depending on the type of progestogen [ 9 ]. However, these changes may be due to other factors [ 10 ]. These factors have been identified as age, excessive weight loss, eating disorders [ 11 , 12 ], a high body mass index (BMI) [ 13 ], strenuous physical exercise often combined with dietary restrictions, problems within the family and at work [ 14 , 15 ], as well as long‐term alcohol consumption [ 16 ]. Alterations in menstrual patterns are, therefore, a frequent gynecological problem for consultation; however, data on their prevalence in Spain and their impact are very limited. This is partly due to the continuous changes in the terminology used and the subjectivity involved in determining some characteristics, such as bleeding volume. Similarly, the association of HC intake with the menstrual cycle is not conclusive and seems to be determined by other factors. With this study, we aimed to determine the characteristics of menstrual patterns in the general population of young Spanish women, identify the prevalence of the main menstrual cycle disorders, and their relationship with hormonal contraceptive use.

The lead / Corresponding author (Sergio Martínez Vázquez) affirms that this manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned (and, if relevant, registered) have been explained.

The authors declare no conflicts of interest.

MATERIAL COMPLEMENTARIO (SPANISH). SUPPLEMENTARY MATERIAL (ENGLISH).