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Shift work can have a detrimental effect on women’s fertility by disrupting their biological clocks, according to a recent study. The body’s circadian rhythm, which governs various bodily functions and responds to light changes, can be disturbed by just four weeks of shift work. This disruption can negatively impact sleep, hormone regulation, reproduction, and digestion. In particular, exposure to light at night can disrupt these internal clocks.

The pituitary gland influences the ovarian activity

The hypothalamus, a small region in the brain, houses the body’s central biological clock. It is responsible for reproductive function, specifically by influencing the pituitary gland, connected to the base of the hypothalamus. This regulation supports ovarian activity and facilitates ovulation.

The study aimed to replicate long-term shift work conditions in female mice. By adjusting their light-dark cycle over four weeks, researchers found that the disruption caused a decrease in fertility. Specifically, the release of the luteinizing hormone, which triggers ovulation, was eliminated due to the alteration of the master circadian clock signalling towards the hypothalamic reproductive circuit. In addition, the transmission of light information from the biological clock to the kisspeptin neurons, which regulate the timing of the hormone surge, was impaired after four weeks of chronic shift exposure.

Disruption of the circadian rhythm affects the female reproductive system

Previous studies on mice and humans have shown that disturbing the circadian rhythm can have detrimental effects on female reproductive health. However, the University of Strasbourg and Institute of Cellular and Integrative Neurosciences (INCI) researchers have discovered that imitating shift work for an extended period leads to a decreased pregnancy rate in female mice. Upcoming studies will examine whether shift work-like patterns have an impact on additional internal clocks.

The circadian rhythm relies on the proper functioning of the master biological clock and the synchronized activity of secondary clocks in the brain and reproductive organs. Understanding how circadian disruption affects reproductive function is crucial for potential interventions to mitigate the negative impact of shift work on women’s fertility. The findings were presented at the 25th European Congress of Endocrinology (ECE) in Istanbul.