Background: Rotating shift work can cause abnormalities in their endocrine system. We conducted a meta-analysis to gain a better understanding of the differences between women working rotating shifts and fixed day shifts in menstrual regularity and dysmenorrhea. Methods: We searched for studies containing relevant keywords that were published between 1990 and 2019 in the Cochrane Library, EBSCO (including the Cumulative Index to Nursing and Allied Health Literature [CINAHL]), MEDLINE, and ProQuest. Data analysis was performed using the software package Comprehensive Meta-Analysis (CMA) Version 3.0. Results: A total of 14 studies met our selection criteria. The pooled odds ratio (OR) comparing the menstrual irregularity of women working rotating shifts and fixed day shifts was 1.35 (95% confidence interval [CI]: 1.28-1.42, p < 0.001). The pooled OR of the women aged 30 years or older was 1.35 (95% CI: 1.28-1.42, p < 0.001); and for the women under 30 years old, the pooled OR was 1.66 (95% CI: 1.13-2.44, p = 0.010). The pooled OR comparing the dysmenorrhea occurrence among women working rotating shifts and fixed day shifts was 1.51 (95% CI: 0.87-2.62, p = 0.139). The pooled OR of the women aged 30 years or older was 2.35 (95% CI: 1.63-3.39, p < 0.001); and for the women under 30 years old, the pooled OR was 1.20 (95% CI: 0.61-2.33, p = 0.601). Conclusions: The results indicate that regardless of age, women working rotating shifts were more likely to experience menstrual irregularity than those working fixed day shifts. With regard to dysmenorrhea, among women aged 30 years or older, those working rotating shifts were also more likely to experience dysmenorrhea than those working fixed day shifts.
Keywords: dysmenorrhea; fixed day shift; menstrual cycles; rotating shift.