Shift work implicated in another pattern of bad health, this time with increased risk of menstrual disruption and subfertility.
An abstract presented at the annual meeting of ESHRE (the European Society of Human Reproduction and Embryology) by Dr Linden Stocker from the University of Southampton, UK, is a meta-analysis of all studies on the subject that have been published between 1969 and January 2013.
It included data on 119,345 women and found that among those working shifts (alternating shifts, evenings and nights), those women had a 33 percent higher rate of menstrual disruption than those working regular hours along with an 80 percent increased rate of subfertility.
Said Dr Stocker:
Whilst we have demonstrated an association between shift work and negative early reproductive outcomes, we have not proven causation. In humans, the long-term effects of altering circadian rhythms are inherently difficult to study. As a proxy measure, the sleep disruption demonstrated by the shift workers in our study creates short- and long-term biological disturbances. Shift workers adopt poor sleep hygiene, suffer sleep deprivation and develop activity levels that are out-of-sync with their body clock. However, if our results are confirmed by other studies, there may be implications for shift workers and their reproductive plans. More friendly shift patterns with less impact on circadian rhythm could be adopted where practical - although the optimal shift pattern required to maximise reproductive potential is yet to be established.
Often, night shifts have been associated with an increased risk in breast cancer. This study found that women who worked only nights didn't have a statistically increased risk of menstrual disruption or difficulty conceiving. However, they did have slightly more miscarriages.
Dr. Stocker said that despite the association, the underlying biological disturbances involved in reproductive difficulties are full of complexities and that they could differ "across all the disease processes." Nonetheless, she added,
If replicated, our findings have implications for women attempting to become pregnant, as well as for their employers.
Source: MNT