Women who struggle with fertility are constantly searching for reasons they cannot get pregnant. And now, another study reveals that the time of day you work and what you do there can have an effect on your ability to conceive.
The research, published Monday in the Journal of Occupational and Environmental Medicine, shows that women who work nights/rotating shifts or do heavy lifting on the job may have fewer and inferior eggs.
The team of researchers studied more than 470 women having fertility treatment and compared the physical demands and schedules of their jobs against four biomarkers — genes or characteristics in the body — known to be linked to their ability to reproduce, also called fecundity.
The biomarkers were numbers of antral follicles indicative of the number of immature eggs remaining in the body, levels of follicle-stimulating hormone that regulated reproductive processes, estrogen levels and numbers of mature eggs capable of developing into healthy embryos.
The team at the Harvard T.H. Chan School of Public Health found that women working non-day shifts and those who had more physically demanding jobs had fewer mature oocytes retrieved after controlled ovarian hyperstimulation. These results provide valuable insight into possible mechanisms linking these occupational exposures with decreased fecundity.
The authors discovered that women who engaged in heavy lifting and moving had 8.8 percent fewer total eggs and 14.1 percent fewer mature eggs compared with women who never lifted or moved heavy objects at work.
The study also found that women who worked nights or rotating shifts also saw a reduction in the number of mature eggs. In addition, they found that in women over 37 or those who were also overweight/obese, this reduction in mature eggs was even greater.
“Our study suggests that women who are planning pregnancy should be cognizant of the potential negative impacts that non-day shift and heavy lifting could have on their reproductive health,” said Lidia Mínguez-Alarcón, a research fellow in the Department of Environmental Health and lead author of the study in a statement.
The takeaway for women: If trying to optimize fertility, avoid heavy lifting at work and keep hours that are consistent with a regular workday.