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

Factors influencing menstrual regularity among female workers: a cross-sectional analysis study

BACKGROUND

Regularity of menstrual cycles is an important indicator of women's health and fertility, and female workers are exposed to several factors, such as sleep disorders, stress, and shift work, that affect their menstrual regularity. This makes it necessary to comprehensively identify the determinants of menstrual regularity. Therefore, this study identified the factors affecting menstrual regularity among female workers from physiological, psychological, and situational dimensions based on the theory of unpleasant symptoms.

METHODS

This was a secondary analysis of the 2010-2012 Korea National Health and Nutrition Examination Survey and utilized the data of 2418 female workers. Based on the theory of unpleasant symptoms, physiological factors included age, age at menarche, childbirth experience, body mass index, and sleep duration. Psychological factors included stress level, depressive mood, and suicidal ideation. Situational factors included education level, household income, consumption of alcohol, engagement in smoking, and work schedule. The χ²-test and hierarchical logistic regression analysis were performed, reflecting the complex sample design.

RESULTS

Age at menarche, childbirth experience, and body mass index among physiological factors and education level and work schedule among situational factors were found to be related to menstrual regularity. A higher risk of menstrual irregularities was found among those who had given birth (versus those who had not), had a high age at menarche (versus those with a low age at menarche), were obese (versus those who had a normal body mass index), had elementary school-level or lesser educational achievements (versus those with college graduate-level or higher educational achievements), and who had a shift work schedule (versus those with a fixed schedule).

CONCLUSIONS

Intervention is needed for female workers who have these risk factors, and special attention must be paid to female workers who have a shift work schedule. Additionally, since body mass index can be controlled, intervention concerning body mass index is necessary to reduce menstrual irregularity.

Nightshift work and irregular menstrual cycle: 8-year follow-up cohort study

BACKGROUND

Irregular menstruation is a major health problem among women, although its association with nightshift work remains controversial.

AIMS

To study the association between nightshift work and irregular menstrual cycle among female workers and investigate any differences according to sleep quality, working hours or obesity.

METHODS

This study included female workers who underwent health examinations from 2012 to 2019. Nightshift work, working hours, sleep quality and menstrual cycles were assessed using self-administered questionnaires. Irregular menstrual cycle was defined as self-reported irregular or ≥36 days. Adjusted odds ratios and 95% confidence intervals (CIs) were calculated by multivariable logistic regression; adjusted hazard ratios (95% CIs) for incident irregular menstrual cycle were calculated by Cox proportional hazard models with time-dependent analysis.

RESULTS

The study participants were 87 147 in the cross-sectional study and 41 516 in the longitudinal study. After adjusting for all covariates in the cross-sectional analyses, the odds ratio for prevalent irregular menstrual cycle among female nightshift workers versus the reference was 1.26 (95% CI 1.2-1.33). In the cohort study, the adjusted hazard ratio for incident irregular menstrual cycle among nightshift workers was 1.95 (95% CI 1.61-2.35) in the period after 6 years. No significant differences were observed among subgroups stratified by sleep quality, working hours or obesity.

CONCLUSIONS

Nightshift work is associated with an increased risk of both prevalent and incident irregular menstrual cycle in female workers without significant interactions by sleep quality, working hours or obesity.

Shift work and menstruation: A meta-analysis study

Background

Shift work is a potential risk factor for women's reproductive health. Evidence suggests that shift work is associated with menstrual disorders, reproductive disturbances, and adverse pregnancy outcomes. However, previous studies did not systematically examine the results of menstrual irregularities, dysmenorrhea, and early menopause at the same time.

Objective

To determine the relationship between shift work and women's menstrual characteristics (e.g., irregular menstruation, dysmenorrhea, and early menopause).

Methods

Four databases (PubMed, Embase, Cochrane, and Web of Science) were searched up to December 2022. The study characteristics and risk assessment values of the literature were extracted from 21 studies that met the criteria. Odds ratios (ORs), relative risks (RRs), hazard ratios (HRs), and 95% confidence intervals (CIs) were calculated to assess the relationship between shift work exposure and menstruation. The included studies were evaluated for heterogeneity, publication bias, sensitivity analysis, and subgroup analysis.

Results

A total of 21 studies with 195,538 female participants, including 16 cross-sectional studies and 5 cohort studies, were included in this meta-analysis. According to the quality evaluation, the included research had high methodological quality. The overall ORs of shift work for the likelihood of irregular menstruation and dysmenorrhea were 1.30 (95% CI, 1.23-1.36) (I2 = 41.9%, P < 0.05) and 1.35 (95% CI, 1.04-1.75) (I2 = 73.0%, P < 0.05), respectively. There was a significant positive association between shift work and the risk of early menopause (HR = 1.09, 95% CI, 1.04-1.14), without significant heterogeneity (I2 = 0.0%, P > 0.05).

Conclusions

This meta-analysis indicated that shift workers have significantly higher odds of menstrual disorders, dysmenorrhea, and early menopause. This study focuses on female reproductive health and has broad implications for adjusting optimal working hours and shift schedules for female workers.

Who is the most precarious among the nonstandard workers? A comparative study of unmet medical needs among standard workers and subtypes of nonstandard workers

OBJECTIVE

Nonstandard workers might have a relatively higher risk of unmet medical needs than standard workers. This study subdivided nonstandard workers to investigate the effects of nonstandard employment on unmet medical needs.

METHODS

We used the Korea Health Panel 2011-2018 data. The independent variable, employment contract, was defined using the nonstandard form described by the ILO: Temporary workers, Part-time workers, and Temporary agent workers. The analytical method used in this study was a panel logit model that accounted for repeated measured participants. By controlling for time-invariant individual-fixed effects, we investigate the relationship between subdivided nonstandard work and the risk of unmet medical needs with reference to standard work.

RESULTS

The results of the analysis clearly showed that compared with standard workers, temporary agency workers had a significantly higher risk of unmet medical needs (Odds ratio = 1.182, 95% CI = 1.016-1.374). The main cause of this phenomenon was economic reasons in this group.

CONCLUSIONS

This study found that temporary agency workers in the general Korean population have a significantly higher risk of unmet healthcare needs. The result of this study implies that financial hardship might be a fundamental health hazard among workers with nonstandard employment.

Menstrual cycle irregularity during examination among female medical students at King Abdulaziz University, Jeddah, Saudi Arabia

Background

Menstrual irregularity is defined as any differences in the frequency, irregularity of onset, duration of flow, or volume of blood from the regular menstrual cycle. It is an important medical issue that many medical students suffer from. The study aimed to determine the menstrual cycle abnormalities women experienced during exams and to investigate the most common types of irregularities among female medical students at King Abdulaziz University in Jeddah, Saudi Arabia.

Methods

A cross-sectional study was conducted among female medical students between September and October 2021 at King Abdulaziz University in Jeddah, Saudi Arabia. For this study, the estimated sample size (n = 450) was derived from the online Raosoft sample size calculator. Thus, 450 female medical students from second to sixth year were selected through stratified random sampling. A validated online questionnaire collected data about demographics, menstrual irregularities during exams, type of irregularities, menstrual history, family history of menstrual irregularities, premenstrual symptoms, medication use, medical and family consultations, and absenteeism. The chi-squared test (χ2) was used to analyze the associations between variables.

Results

A total of 48.2% of participants had menstrual irregularities during exams. The most common irregularity was dysmenorrhea (70.9%), followed by a lengthened cycle (45.6%), and heavy bleeding (41.9%). A total of 93% of medical students suffered from premenstrual symptoms and 60.4% used medication such as herbal medication and home remedies to relieve menstrual irregularities, and 12.1% of the students missed classes due to menstrual irregularities. A non-significant relationship was found between menstrual irregularities during exams and students’ demographics, academic year, and age at menarche, while oligomenorrhea, a heavier than normal bleed, a longer than normal cycle, and missing classes due to menstrual irregularities were significantly higher among single students as opposed to married students.

Conclusion

The results showed that female medical students have a significant frequency of menstruation abnormalities during exams period. Colleges should raise awareness among medical students about coping with examination stress and seeking medical care for menstrual abnormalities.

The Association Between Long Working Hours of Parents and Dyslipidemia in Their Children

The purpose of our study is to examine the association between children's low-density lipoprotein cholesterol (LDL-C) levels and their parents' working hours. We used data from the 2010–2018 Korea National Health and Nutrition Examination Survey in which lipid profile samples of 3,799 children were eligible. Logistic regression analyses were used with an outcome variable of the dichotomous LDL-C group and an exposure variable of the father's and mother's working hours, respectively. In logistic regression models adjusted for age, sex, household income, education level of children and parents, and working hours of the parents, mothers' working hours more than 52 h per week were significantly associated with their children's dyslipidemia [OR 2.14, 95% confidence interval (CI) 1.33–3.47] compared to working 40 h or less, whereas fathers' working hours did not show statistical significance (OR 1.08, 95% CI 0.71–1.66) in the same manner. The association was greatest for elementary school students for mothers working more than 52 h per week (OR 3.42, 95% CI 1.64–7.14) compared to those working hours 40 h per week or less. Mothers' long working hours were associated with a higher prevalence of dyslipidemia in their children. The association was strongest for elementary school students. Proper working time of parents is required for their children's health.

Comparative analyses of occupational injuries among temporary agency worker and direct contract workers: Findings from the Korea Health Panel 2009-2018

Objectives

Several studies have reported health or safety risk of temporary agency workers (TAW). Since most of the studies are just cross‐sectional studies, we intended to identify the risk of occupational injury in TAW, using longitudinal study design.

Methods

The Korea Health Panel 2009–2018 data were used in the study. For the statistical analysis of this study, we used a panel logit model to identify the risk of occupational injury in TAW compared to direct contract workers (DCW).

Results

There was no significant difference in risk of occupational injury between TAW and DCW among the overall population (adjusted OR 0.920, 95% CI 0.600–1.411). However, there was a significant increase in occupational injury in women (adjusted OR 2.134, 95% CI 1.092–4.170) and the “19–34” age group (adjusted OR 2.744, 95% CI 1.103–6.825) of TAW.

Conclusions

This study provides evidence for vulnerable groups such as women and younger age groups in the relationship between TAW and occupational injury.

Effect of long work hours and shift work on high-sensitivity C-reactive protein levels among Korean workers

Objective We aimed to investigate the association between low-grade inflammation as indicated by high-sensitivity C-reactive protein (hsCRP) level and organizational factors, such as work hours and shift work. Methods We evaluated 7470 young and middle-aged workers who participated in the Korea National Health and Nutrition Examination Surveys from 2015-2018. Work hours were determined from self-reported questionnaires. Shift work was defined as a non-daytime fixed work schedule. An interaction effect between shift work and long work hours on the hsCRP level was estimated using relative excess risk due to interaction (RERI) and attributable proportion (AP) with 95% confidence intervals (CI). Results Increased hsCRP levels were prevalent in 25.2% of the study population. There was a significant association between long work hours and increased hsCRP, especially among middle-aged men [odds ratio (OR) 1.50 (95% CI 1.20-1.87) for moderately increased hsCRP and OR 1.62 (95% CI 1.14-2.30) for highly increased hsCRP]. There was a significant interaction effect between long work hours and shift work on increased hsCRP among middle-aged workers. The RERI were 0.03 (95% CI 0.02-0.04) and 0.56 (95% CI 0.45-0.68) among middle-aged men and women, respectively. The AP were 0.02 (95% CI 0.01-0.03) and 0.36 (95% CI 0.31-0.40) among middle-aged men and women, respectively. Conclusion There was no significant association between shift work and the level of hsCRP. Long work hours were related to low-grade inflammatory processes, but only in middle-aged workers. There was an interaction effect between long work hours and shift work for increased hsCRP, especially in middle-aged women.