Jobs that involve irregular shifts and heavy lifting on a regular basis could reduce a woman’s fertility. The impact is greater among overweight and obese women, according to researchers at Harvard University.
Although researchers from the Harvard T.H. Chan School of Public Health admit they do not know the cause, they believe that women in their reproductive years may need to consider this when trying to conceive.
“Our study suggests that women who are planning pregnancy should be aware of the potential negative impacts that non-day shift and heavy lifting could have on their reproductive health,” said Lidia Mínguez-Alarcón, lead author of the study, which was published in the journal Occupational and Environmental Medicine
The researchers studied more than 470 women having fertility treatment (IVF) and compared the physical demands and schedules of their jobs against four biomarkers (genes or characteristics in the body like numbers of antral follicles, number of immature eggs in the body, estrogen levels, numbers of mature eggs capable of developing into healthy embryos) known to be linked to their ability to reproduce, also called fecundity.
Women reporting heavy lifting and moving (including nurses and interior designers) had 8.8% fewer total eggs and 14.1% fewer mature eggs compared with women who never lifted or moved heavy objects at work. This reduction in mature eggs was greater in women who were also overweight, obese or over the age of 37. Women who worked nights or rotating shifts also had reduced number of mature eggs.
No association was seen between these aspects of the women’s occupation and their levels of follicle-stimulating hormone or estrogen.
Researchers were unable to assess the potential impact of several factors including working hours, testosterone levels or childhood exposure to smoking on the participants’ fertility, but they suggested stress caused by a shifting body clock or physical exertion could explain the findings.
Image credit: http://americanpregnancy.org/is-it-safe/lifting-pregnancy/