Menstrual disorders, especially dysmenorrhea and premenstrual syndrome, are considered to affect the quality of life (QOL) of women during reproductive age. When the symptoms are severe, social activity is very limited during menstruation, reducing QOL in women. These disorders are frequently encountered in young women around adolescence [1]. Menstrual and reproductive factors including estrogenic agents have also been proposed to be associated with malignant diseases in the reproductive organs such as endometrial carcinoma and breast carcinoma as well as those in other organs [2,3]. From these perspectives, it is important to precisely evaluate the current status of menstrual disorders in young women in order to manage not only the present, but also future QOL.

Dysmenorrhea is mainly classified into functional dysmenorrhea and organic dysmenorrhea based on pathogenesis [1]. In general, functional dysmenorrhea is caused by ovarian dysfunction, which is frequently manifested as irregular menstruation. Since this disorder is commonly derived from immaturity of hypothalamic-pituitary-ovarian function, the symptom can be expected to spontaneously recover along with the maturation process of endocrinological feedback system. In contrast, endometriosis and uterine myoma, which are representative diseases causing organic dysmenorrhea, gradually become extended along with sequential menstruations, inducing constant pelvic pain throughout the menstrual cycle [4]. During reproductive ages, since these diseases may cause infertility in the future. evaluation of the current status of menstrual disorders in young women should be an important social issue [5].

On the other hand, premenstrual syndrome is a multifactorial syndrome that affects adolescent girls with a high frequency. This syndrome is characterized by manifestation of pschychological disorders such as irritability, depression, and mood swings and/or somatic complaints including abdominal bloating, peripheral edema, general fatigue and acne before menstruation [6]. These symptoms are recurrent according to menstrual cycles and rapidly disappeared just after onset of menstruation. Although various etiologies of premenstrual syndrome such as elevated prolactin levels, hypoglycemia or vitamin deficiencies have been proposed, none of these theories has been definitively proven [7].

In this study, to estimate the current status of young women with menstrual disorders in Japan, the relation between dysmenorrhea and premenstrual symptoms as well as irregular menstruation was investigated by responses to a questionnaire from female students ranging from 18 to 20 years old, who studied at Ashiya College during the recent 5 years.

Pelvic pain, which is an integrated physical sense [9], is conducted through afferent pathways by the hypogastric sympathetic and parasympathetic nerves [10,11]. Primary dysmenorrhea is a common gynecological disorder in young women [12]. It begins within 6-12 months from menarche and is characterized by localized pain in the abdominal inferior quadrants. Dysmenorrhea is an important clinical sign for local inflammation in the pelvis. In young women, this symptom is frequently caused by hormonal disorders in ovarian function [1]. Under inadequate balance of ovarian sex steroid hormones, a high amount of prostaglandins is considered to be produced in the uterus during menstruation [13], causing excess contraction of uterine muscle and inducing functional dysmenorrhea [14]. To predict dysfunction in the hypothalamic-pituitary-ovarian axis, irregular menstruation is one of the reliable clinical symptoms.

To precisely evaluate the students with normal ovarian function, we strictly defined regular menstrual cycle as constant 26-32-day intervals in each menstrual cycle. Based on sequential information over a 5-year period between 2001 and 2005, the present study showed that students with irregular menstruation comprised one third of the participants, indicating that considerable numbers of young women have menstrual disorders. It was also shown that students with irregular menstruation frequently had a higher BMI. Recently, we observed that there is considerable discrepancy between BMI and self-recognition of adequate body weight in young students at Ashiya College and that those with relatively high BMI scores tended to undergo insufficient food intake and dietary habits despite being within normal BMI range [15]. It is well known that inappropriate dieting often induces amenorrhea in young women and may cause ovarian dysfunction during subsequent reproductive years [16,17]. A vegetarian low caloric diet is reported to lead to menstrual cycle disorders and a short luteal phase [18,19]. Thus, dysfunction in the hypothalamic- pituitary-ovarian axis can be induced by nutritional deficiency. It has been widely accepted that irregular menstruation in young students is partially caused by an inadequate nutritional state [20]. Recently, we found that young women who skip breakfast have a significantly higher degree of dysmenorrhea symptoms than those who eat breakfast [6]. It was also reported that intake of dietary fiber was inversely correlated with the menstrual pain in young Japanese women [21]. We also observed that diet during adolescence has long-lasting adverse effects on dysmenorrhea [22] in young women. These findings suggest that an inadequate nutritional state has adverse effects on dysmenorrhea in young women [5]. In accordance with this study, students with irregular menses reported a higher intensity of dysmenorrhea (Fig. 1). Although serum levels of gonadotropins or ovarian sex steroid hormones were not examined, these findings suggest that functional disorders are involved in dysmenorrhea in young students with irregular menstruation.

Recently, increasing attention has been paid to the adverse effects of premenstrual syndrome on the quality of life in Japanese women. Although more than 100 symptoms and/or signs are considered to be involved in premenstrual syndrome, there is no specific laboratory test to precisely diagnose premenstrual syndrome. In this study, to obtain an accurate answer from the participants, we prepared a simple questionnaire and focused on 10 symptoms that mainly characterize premenstrual syndrome. Notably, this study demonstrated that almost half of the young women surveyed have premenstrual symptoms. Although the criteria employed in this study were not as strict as the criteria for clinical diagnosis of premenstrual syndrome, this high incidence is compatible with a recent report showing that about 60% of adolescence complain of premenstrual syndrome based on the criteria described in the Manual of Mental Disorders-IV [23,24]. In addition, this study showed that young Japanese women with premenstrual symptoms have a higher incidence of menstrual pains, suggesting a cross relationship between premenstrual syndrome and dysmenorrhea. Although functional dysmenorrhea frequently shows irregular menstruation, there was no significant relation between the incidences of premenstrual symptoms and irregular menstruation in these students, suggesting that dysmenorrhea with premenstrual symptoms is not necessary derived from functional disorders. Therefore, it should be noted that students with dysmenorrhea and premenstrual symptoms may have a risk for some organic diseases causing dysmenorrhea.

In conclusion, this study confirmed that considerable numbers of young women in Japan have irregular menstruation and premenstrual symptoms. Although this study did not show any significant relation between irregular menstruation and premenstrual symptoms, female students reporting premenstrual symptoms also complained of higher intensity of menstrual pains. From these findings, this study notably suggests that some organic diseases causing dysmenorrhea are latently proceeding in young Japanese women with premenstrual symptoms. Since dysmenorrhea and premenstrual syndrome may influence QOL in women not only in the present but also in the future, these results should be noted from the perspective of future reproductive function.