Night Shift Work and Its Impact on Women's Reproductive Health

Recent research highlights the potential reproductive risks associated with working night shifts. A study presented at ENDO 2025, the annual meeting of the Endocrine Society, reveals that women engaged in night shift work may face a higher likelihood of experiencing irregular menstrual cycles and hormonal imbalances. This disruption is linked to altered internal biological timing caused by shift work-like light exposure, which can adversely affect reproductive health.

To explore these effects, scientists employed a mouse model simulating rotating light schedules that mimic night shift patterns. The experiment involved adjusting the light-dark cycle every four days over a period of 5 to 9 weeks. Results showed that about half of the female mice developed irregular menstrual-like cycles, hormonal disruptions, and signs of ovarian stress, while others maintained normal cycles. Regardless of cycle regularity, the altered light pattern also affected the timing of ovarian and uterine functions.

Interestingly, even mice with disrupted reproductive cycles could conceive, but their pregnancies resulted in smaller litters and a higher incidence of labor complications. This suggests that shift work may contribute to pregnancy challenges even in women with seemingly regular reproductive functions.

The research emphasizes that individual resilience to circadian disruptions varies, and some women may be more vulnerable than others depending on how their bodies manage hormonal balance amidst irregular sleep-wake cycles. These findings highlight the importance of considering reproductive health risks when working night shifts.

Looking ahead, scientists aim to further investigate how these light-induced disruptions affect pregnancy processes, which could inform guidelines to help women safeguard their fertility and pregnancy outcomes while managing shift work schedules. Ultimately, understanding individual differences in adaptation could lead to more personalized recommendations for women balancing work and reproductive health.

Source: https://medicalxpress.com/news/2025-07-night-shift-irregular-periods-hormonal.html