Association between irregular menstrual cycles and occupational characteristics among female workers in Korea

To examine the association between irregular menstrual cycles and occupational characteristics among Korean female workers.

We analyzed data on paid female workers from the Korea National Health and Nutrition Examination Survey (KNHANES) V (2010-2012).

We evaluated the possible associations between irregular menstrual cycles and work variables (occupational classification, working hours, and shift work) using univariate and multivariate logistic regression analyses. Weighted prevalence was calculated according to each work variable to approximate the Korean population.

Irregular menstrual cycles were the most common in women in the 'pink collar' group (16.61%). The frequency of irregular menstrual cycles was 2-fold higher in women working >60 h per week (25.64%) than in those working 20-60 h per week (11.09%). Irregular menstrual cycles were more prevalent in shift workers (15.85%) than in non-shift workers (11.06%). A significantly high risk of irregular menstrual cycles was found for pink-collar occupations (adjusted odds ratio [OR] = 1.687, 95% confidence interval [CI] = 1.044-2.710, reference: white-collar occupation group) and in women with long working hours (adjusted OR = 2.139, 95% CI = 1.243-3.559, reference: 20-60 working hours group) and shift work (adjusted OR = 1.487, 95% CI = 1.028-2.118, reference: fixed working schedule group).

Our study showed associations between irregular menstrual cycles and occupational characteristics of female workers. Long working hours, shift work, and pink-collar occupations are positively associated with irregular menstrual cycles. Therefore, working hours and shift schedules for female workers should be structured considering these factors. Further research is needed to determine the optimal working time and shift schedules for female workers.