Shift work linked to delayed onset of menopause
Click Here to Manage Email Alerts
Women who were employed in rotating or night shift work at some point in their lives are more likely to experience delayed onset of menopause compared with women working only during the day, according to study data published in Menopause.
“Investigating and identifying the modifiable factors of age of natural menopause, like shift work exposure among working populations, is of clinical relevance given the potential adverse health outcomes associated with variations in menopausal timing,” Durdana Khan, MPH, a PhD scholar in the department of kinesiology and health sciences at York University in Toronto, told Healio. “The findings, while preliminary, add insight on the impact of shift work on reproductive function and further elucidate the role of circadian regulation on timing of natural menopause.”
Khan and colleagues analyzed data from 3,688 premenopausal women in the Canadian Longitudinal Study on Aging who provided information on menopausal status and employment history (mean age, 48.9 years; 94.3% white). The cohort was followed from 2015 to 2018. Work schedules were classified as daytime work, night shift or rotating shift. Participants were asked to describe their current work schedule and which work schedule they worked with the longest. Menopausal status and age at menopause onset were self-reported.
At 3 years, 40.7% of the study cohort reported attaining natural menopause, and 20% of the women said they had performed shift work at some point in their careers. Of the cohort, 3.6% said they were working night shift at baseline, and 8.1% reported working a rotating shift job. When asked which shift they worked the longest, 4.7% said they worked night shift longest, and 13.1% reported working rotating shifts the longest.
Women who worked a rotating shift or night shift at any point in their lives were more likely to have later age at menopause onset compared with day shift workers (HR = 0.77; 95% CI, 0.61-0.98). Women working a rotating shift at baseline were more likely to experience later menopause than day shift workers (HR = 0.64; 95% CI, 0.46-0.89). Those who reported most often working rotating shifts were more likely to be older at menopause onset than those who worked during the day the longest (HR = 0.65; 95% CI, 0.49-0.86).
“While the exact underlying mechanisms aren’t known, rotating shift work has been hypothesized to be more disruptive to the circadian rhythm than regular night work and has been studied previously as a risk factor for adverse reproduction-related outcomes,” Khan said. “The delaying effect of rotating shift work on menopause timing in our study might be due to effects of circadian disruption on estrogen production. To develop a more complete picture of the relationship between shift work and onset of menopause, additional studies will be needed to confirm the association as well as determine any physiological pathways that are influenced.”
Khan said future studies should examine further details of shift work and how they relate to age at menopause, such as the type and direction of rotating shifts, the number of consecutive night shifts and the number of days off between shifts.
For more information:
Durdana Kahn, MPH, can be reached at drkhan@yorku.ca.
Perspective
Back to TopShadab A. Rahman, PhD and Hadine Joffe, MD
This study evaluates whether shift work may be associated with a change in the age of onset of natural menopause. The authors reviewed self-reported menopausal status and employment history data from nearly 3,700 women from the Canadian Longitudinal Study on Aging.
The authors found that compared with women who worked day shifts, women who worked rotating or night shifts at any point in their lives were more likely to experience onset of menopause approximately 1 year later. Additionally, among women who were working during the 3-year observation interval, women working rotating shifts were more likely to experience menopause approximately a year later than women working day shifts. In both cases, the 1-year change appears small, although statistically significant.
The authors propose shift work-associated disruption in circadian rhythms in female reproductive hormones as a possible mechanism underlying these findings. They also discuss limitations of the study, including missing pertinent details related to characterizing work history and reproductive health. These epidemiologic findings are thought provoking. Shift work is typically associated with adverse health effects, whereas in this case an adverse impact is not clear. An increase in the age of menopause is protective when it comes to cardiovascular and other health outcomes. Additional work is warranted to elucidate mechanisms, including circadian rhythm disruption, sleep deficiency and metabolic changes associated with shift work in contributing to these changes in women’s reproductive health and their longer-term downstream effects on overall health and well-being.
Collapse
Read more about
Click Here to Manage Email Alerts