The results of this study can be divided into two levels. First, without sample stratification, we founded that there was no association between alcohol consumption and dysmenorrhea among university students in North China. However, when the samples are stratified based on the AAM, we founded that participants with AAM ≥ 13 years old had higher prevalence of dysmenorrhea, and the prevalence rate of dysmenorrhea showed a dose-response association with alcohol consumption.
Our study is one of the few efforts to investigate the association between alcohol consumption and dysmenorrhea risk among female college students. Dysmenorrhea was reported to be associated with a variety of factors, such as mother's history of passive smoking and dysmenorrhea. Nevertheless, few studies have explored the relationship between alcohol consumption and dysmenorrhea. The results of the unstratified multivariate analyses we studied were consistent with previous reports by several scholars, Sznajder et al. reported that alcohol use was not associated with any type of gynecological pain, including dysmenorrhea. Potur et al.  identified the prevalence and symptoms of dysmenorrhea in Turkish students and reported that alcohol consumption did not influence the prevalence of dysmenorrhea. Midilli et al. assessed the characteristics of menstruation, dysmenorrhea and factors affecting dysmenorrhea among 488 health school students at the Celal Bayar University Manisa Health School in 2014, and reported that there was no significant association between dysmenorrhea and consumption of salt, tea, coffee, or alcohol.
However, studies on the relationship between alcohol and dysmenorrhea have been inconsistent. Some have shown that alcohol consumption increases the incidence and severity of PMS and dysmenorrhea[25–28]. At present, the study of Nybergetal et al. may explain the relationship between the two in terms of hormones, they found that a dose of alcohol affected the serum concentrations of allopregnanolone throughout the menstrual cycle, which might affect the occurrence of severe premenstrual syndrome and dysmenorrhea. Our data provided new evidence in support of the relationship between alcohol consumption and the risk of dysmenorrhea.
Menarche is a milestone event in the growth and development of women and a sign of sexual maturity. Several surveys have found that in recent decades, girls of different races, countries and regions have experienced the phenomenon that the AAM continues to advance[30, 31]. The average age of menarche in China is 12.27 years old (95% CI, 12.16ཞ12.39), and the average age of menarche in this study is 13.42 ± 1.30 years, so we chose AAM 13 to differentiate all students into two groups for further analysis. AAM may be a possible risk factor for obesity, breast cancer, mental illness and dysmenorrhea[11, 15–17]. Our results showed that the age among participants with dysmenorrhea was significantly younger than that of participants without dysmenorrhea (P < 0.001). It is suggested that the younger the AAM, the greater the risk of dysmenorrhea, which is consistent with the results of Harlow et al. Their study found that the earlier the AAM, the higher the incidence, duration and severity of dysmenorrhea. Their study found that the earlier the AAM, the higher the incidence and the longer the duration, and the more severe the pain.
According to studies, the effect of stratification of AAM on the association between alcohol consumption and dysmenorrhea may due to the following reasons. First, the association between younger than 13 years old of AAM and dysmenorrhea may be due to higher levels of estrogen caused by hormone patterns in the early stages of sexual maturity. Second, Participants with AAM < 13 years old might reduce their alcohol use and consumption, or avoid alcohol use, due to their higher frequency of dysmenorrhea. Third, for participants older than 13 years old of AAM, the function of the adrenal and hypothalamic pituitary-gonadal axis (HPG) may mature later. In this case, alcohol consumption might disrupt the unstable maturation process, which may lead to many of the physical and hormonal changes and even dysmenorrhea.
The study had some limitations. First, the study was based on a cross-sectional sample that lacked a longitudinal trace, which might lead to selection bias. Second, alcohol use, alcohol consumption, and dysmenorrhea were evaluated by means of a retrospective questionnaire, which might be subject to recall bias. Accurate responses from the study participants were crucial for the study validity. Third, we do not have enough samples to examine the effects of alcohol consumption and alcohol consumption on dysmenorrhea in female college students younger than 13 years of age. Fourth, several underlying factors that could affect the magnitude of dysmenorrhea were not sufficiently investigated, including age at first alcohol use, disease which could cause dysmenorrhea, lifestyle, drug abuse, exercise, and genotypic variation. Future studies including these additional factors are needed. Finally, the questionnaire did not query about the occurrence of dysmenorrhea before the start of alcohol use, which may possibly have a confounding effect on the association of alcohol use and alcohol consumption with dysmenorrhea, due to the participants with dysmenorrhea may tend to avoid using alcohol or reduce alcohol consumption.