Prevalence of dysmenorrhea in female students in a Chinese university: a prospective study

doi:10.4236/health.2010.24046

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Vol.2, No.4, 311-314 (2010) Health

doi:10.4236/health.2010.24046

Prevalence of dysmenorrhea in female students in a

Chinese university: a prospective study

Hong-Gui Zhou1, Zheng-Wei Yang2, Students Group3

1Department of Gynecology and Obstetrics, the Affiliated Hospital of North Sichuan Medical College, Nanchong, China

2Morphometric Research Laboratory, North Sichuan Medical College, Nanchong, China; zwyang@nsmc.edu.cn

3Undergraduate students of North Sichuan Medical College, including Hong-Yu Chen, Hua-Qiu Chen, Li Chen, Ling Chen, Yu-Zi

Chen, Xia Chuan, Chun-Ni Deng, Li-Tao Fan, Na Fu, Cui-Mei Gan, Yan Gou, Jing Guo, Li-Ya He, Ya-Jie Hou, Qin Hu, Xiao-Juan

Huang, Lin-Ling Li, Xiao-Zuo Li, Xiao-Lan Lin, Chun-Xia Liu, Dan Liu, Xu Liu, Yin-Hua Peng, Jun Qian, Xue-Fang Ren, Wen

Tang, Hai-Bo Wang, Hui-Min Wang, Qi Wang, Qian-Qian Wang, Yao Xie, Yao-Yao Yu, Ling Zeng, Huan Zhang, Qiong-Yue Zhang,

Jian-Ping Zhao, Chang-Feng Zhou, Xue-Yu Zhou, Yang-Lin Zhou (in surnames’ alphabetical order).

Received 28 December 2009; revised 20 January 2010; accepted 25 January 2010.

ABSTRACT

This study aimed to investigate the prevalence

of dysmenorrhea in a prospective approach.

Menstruation-related diary data were obtained

from 2640 female college students in North Si-

chuan Medical College; dysmenorrhea and re-

lated factors were analyzed. Dysmenorrhea

occurred in 56.4% of students; 6.5% of dys-

menorrheal students suffered from “hard to

bear” (unbearable) menstrual pain, and 6.5%

had pre-menstrual dysmenorrhea. The more

severe dysmenorrhea was, the longer dys-

menorrhea lasted, and th e longer the duration o f

menstruation and the larger the amount of

menstrual blood flow appeared to be. Dys-

menorrhea occurred on 37% of the menstrual

dates on average and was unrelated to irregu-

larity of menstrual cycles. The percentages of

students taking medicine with mild, moderate

and unbearable dysmenorrhea were 4.0%,

13.3% and 23.7%, respectiv ely.

Keywords: College Students; Dysme norrhea; Pro-

spective Study

1. INTRODUCTION

Many investigations have been undertaken to determine

the prevalence of dysmenorrhea (painful menstruation),

the commonest (not necessarily the most serious) com-

plaint associated with menstruation [1]. The prevalence

varied widely between investigations. As published in

English, for example, the prevalence (rate of occurrence)

of dysmenorrhea ranged from 72.3% to 89.5% in Nige-

rian and Turkey university students [2,3], and from

59.7% to 85.0% in adolescent girls or young women

[4-8]. In China, university/college students were the

main subjects investigated and the prevalence of dys-

menorrhea (reported in Chinese journals) varied from

31.5%-41.9% [9-13] to 57.1%-79.4% [14-18]. Previous

investigations were, however, retrospective ones by

means of questionnaires. In some investigations it was

stated that the dysmenorrheal data were about the men-

strual pain that occurred every month or frequently [11]

or during the past 3 months [8], and in most other inves-

tigations it was unk nown whether the dysmen orrhea was

defined as the menstrual pain that occurred during the

past 1 or several weeks, or during the last 1 or several

periods. This would cloud the prevalence data. This cur-

rent investigation was therefore undertaken, by adopting

a prospective approach (by means of diary), to stud y the

prevalence of dysmenorrhea in female students in a

Chinese university.

2. METHODS

The students investigated were Grades 2004-2007 fe-

male undergraduate students residing on the campus of

North Sichuan Medical College. 37 of them and 2 male

undergraduates constituting the Students Group were

recruited as volunteers to assist in the investigation.

A diary table was distributed to students on October

21, 2007. They were requested to keep record of their

menstrual dates, amount of menstrual blood flow (too

little, moderate or too much), dysmenorrhea (lower ab-

dominal pain associated with menstruation) and medica-

tions taken for menstrual disorder. The completed diary

tables were collected b y January 1 8, 20 08 ( the end of th e

semester).

2876 students participated in the study. 230 of them

wrote on the diary that they forgot to fill in part of the

menstrual data and 6 students had no menstruation dur-

H. G. Zhou et al. / Health 2 (2010) 311-314

312

ing investigation. These students being excluded, the

analysis in this study was based on data from the other

2640 students. These students were, on October 2007 at

the beginning of investigation, aged 20.3  1.3 (SD) full

years (range, 16-26; median, 20; 5th and 95th percentiles,

18 and 22).

The first menstruation during the period of investiga-

tion was used for the analysis of dysmenorrhea (includ-

ing pre-menstrual dysmenorrhea), which was divided

into 3 levels: mild (not affecting life or work, without

worry or concern), moderate and unbearable (the origi-

nal Chinese words means “hard to bear” literally). When

a student had 1 or more days of unbearable pain, she was

classified into the group of unbearable dysmenorrhea.

When she had no unbearable pain but had 1 or more

days of moderate pain, she was grouped into moderate

dysmenorrhea. Mild dysmenorrheal students had mild

but no unbearable or moderate pain.

3. RESULTS

The prevalence of dysmenorrhea was 56.4%. 64.7% of

the dysmenorrheal students had mild dysmenorrhea,

28.8% moderate dysmenorrhea and 6.5% unbearable

dysmenorrhea (Table 1). 3.67% of the 2640 students had

pre-menstrual dysmenorrhea and 1.10% had only

pre-menstrual pain without pain during menstruation . An

average of 8.0% of dysmenorrheal students took medi-

cine; the percentages of students taking medicine with

mild, moderate and unbearable dysmenorrhea were 4.0%,

13.3% and 23.7%, respectively.

The average duration of menstruation was 3.79  1.22

days (median, 4 days); 261 (9.89%) students had abnor-

mal menstrual cycles [19 ] > 40 days or < 18 days. Com-

pared to non-dysmenorrheal students, dysmenorrheal

students were slightly older in age, had slightly longer

menstruation, and had more days on which they felt

there was more menstrual blood loss (Table 1). The

number of dates with dysmenorrhea during menstruation

increased significantly with the increase of dysmenor-

rheal levels (Table 1). In dysmenorrheal students, the

mean number of menstrual dates in the menstrual p eriod

was 4.84  1.24 and dysmenorrhea occurred on 37.1% 

22.8% of the menstrual dates. [Note, for each period of

menstruation, the number of menstrual dates is 1 larger

than the duration (days) of menstruation.] There was no

significant difference in the percentage of students with

abnormal menstrual cycles between groups of students

without and with dysmenorrhea (Table 1).

4. DISCUSSION

This is a large prospective investigation undertaken to

study the prevalence of dysmenorrhea. It demonstrated

that the prevalence of dysmenorrhea in female college

students in a Chinese university was 56.4%. It also

demonstrated for the first time that 1) dysmenorrhea

occurred on < 40% of the menstrual dates on average,

and 2) the more severe dysmenorrhea was, the longer

dysmenorrhea lasted: the mean number of dysmenor-

rheal dates during menstruation in unbearable dys-

menorrheal students was > 60% larger than that in mild

dysmenorrheal students (Table 1). It was previously

reported that the severity of dysmenorrhea increased

with increasing duration of menstruation or amount of

menstrua l flow [5-6 ]. As also shown in the cu rren t study,

the prevalence or severity of dysmenorrhea was unre-

lated to irregularity of menstrual cycles (Table 1).

The prevalence of dysmenorrhea in college students, a

relatively convenient sample to study, was reported with

wide variation in pr evious studies (see the Introduc tion).

A recent (data collected in June 2006) large (n=15392)

study in 7 universities for minority nationalities reported,

for example, an overall prevalence of 65.6% among the

second and third year college students on campus, with

no significant differences between major nationalities;

however, the prevalence was 84.8% in 1 university (n =

2097) [18]. Strictly speaking, our result of 56.4% ob-

tained prospectively was not comparable to previous

(retrospective) results. A dysmenorrheal woman was

defined in this study as suffering from dysmenorrhea in

one (the first) menstrual period during investigation. So

the dysmenorrheal prevalence obtained in this study re-

flected the prevalence among the women at certain time

point. If a woman was defined as dysmenorrheal even if

dysmenorrhea occurred in only one of her past 10 or 20

periods, each woman would likely be dysmenorrheal, i.e.

the prevalence would be approximating to 100%. The

prevalence (85%) of dysmenorrhea occurring during the

past 3 months among high school students [8], for ex-

ample, would certainly overestimate the prevalence at

certain time point. Previous studies were usually retro-

spective, associated with recall bias, and in most previ-

ous studies it was unknown how the dysmenorrhea was

defined (see the Introduction).

Severity of dysmenorrhea is a subjective feeling,

which may be variable between groups of women. Se-

vere (in comparison with mild or moderate) dysmenor-

rhea was reported in 10%-42% of Western dysmenor-

rheal women [4-6,8] while the percentage was 6.5%-

6.7% in Chinese dysmenorrheal college students [9,15].

Menstruation may be likened to an internal bleeding,

wound or trauma and would naturally cause some con-

cern, painful or uncomfortable feeling, to which women

would get accustomed one way or another. It is therefore

those who feel “hard to bear” (unbearable) that we

should pay special attention to. As estimated in the pre-

sent study, this subgroup of people with unbearable

H. G. Zhou et al. / Health 2 (2010) 311-314

313

Table 1. Main results (mean  SD) for college students without dysmenorrhea and with mild, moderate or unbearable dysmenorrhea.

Without

(n = 1150) Mild

(n = 964) Moderate

(n = 429) Unbearable

(n = 97)

Age (full years) * 20.2  1.3abc 20.4  1.4 20.5  1.3 20.7  1.3

Duration of menstruation (days) * 3.72  1.20 3.81  1.20 3.91  1.30 3.90  1.33

No. of dates with dysmenorrhea during men-

struation * - 1.49  0.91bc 2.07  1.06c 2.43  1.31

No. of dates with little blood flow during men-

struation * 1.50  1.49 1.54  1.41 1.70  1.48 1.69  1.52

No. of dates with moderate blood flow during

menstruation * 2.99  1.71 2.97  1.54 2.81  1.60 2.64  1.77

No. of dates with much blood flow during

menstruation * 0.23  0.61abc 0.29  0.60bc 0.40  0.67 0.57  0.93

Percentage of students with abnormal men-

strual cycle # 10.17% 9.02% 11.19% 9.28%

*Data were significantly different (P  0.05) between the 4 groups or the 3 dysmenorrheal groups (Kruskal-Wallis one way analysis of variance on

ranks); significantly different (P  0.05) from the group of mild a, moderate b or unbearable c dysmenorrhea (Du nn's method for multiple comparison).

#Abnormal menstrual cycle:  17 or  41 days; there was no significant di fference between the percentages (2 test: P > 0.50).

dysmenorrhea accounted for 6.5% of the dysmenor-

rheal students, similar to the “severe” (treatment was

needed and school study could not be continued) re-

sults (6.5%-6.7%) previously reported in Chinese col-

lege students [9,15]. Even with unbearable dysmenor-

rhea, the students just seemed to bear it without taking

medicine—less than 25% of them took medicine. Men-

struation-related health education programs are there-

fore needed on campus to promote the menstrual health

of students.

The percentage of dysmenorrheal students taking

medicine for dysmenorrhea was previously reported to

be 50%-58% among Turkey and British undergraduate

students [3,20], 52%-58% among American and Aus-

tralian high school students [7,8], more than 43.8%

among Chinese undergraduate students [18], and

33%-38% among young Sweden women [5,6]. These

results are much higher than our result (8.0%). This

may be indicative of wide variation in the attitude of

medicine taking or in the tolerance to pain between

groups (people) or regions (places), and/or indicative of

the “cumulative effects” in retrospective studies, like

the overestimation of dysmenorrheal prevalence as de-

scribed above.

Dysmenorrhea in the present study is essentially pri-

mary dysmenorrhea [1] since no students in this investi-

gation reported underlying pelvic pathology during study.

In talking with some dysmenorrheal students during

study, we identified a couple of students whose dys-

menorrhea might be secondary, but this was not con-

firmed because they did not seek further consultation or

examination.

5. ACKNOWLEDGMENTS

This study was supported by grants from the Nanchong Bureau of

Science and Technology (N2007-SF010) and the Sichuan Department

of Education (08ZA110).

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