Women with jobs that are physically demanding or require working irregular hours — such as evenings, nights, or rotating shifts — may have decreased fertility, according to a new study. Those with such positions were found to have fewer viable eggs, which can potentially make it harder for a woman to conceive.
While previous studies have looked at the impact that jobs with heavy lifting or shift work can have on infertility, a team of scientists from Harvard T.H. Chan School of Public Health sought to investigate whether these positions can have a direct impact on biomarkers in a woman’s body. They examined close to 500 women undergoing infertility treatment between 2004 and 2015, and found that those who lifted or moved heavy objects at work had 8.8 percent fewer eggs and 14.1 percent fewer mature eggs. They also discovered that non-daytime schedules further negatively impact a woman’s egg reserves.
Published in the journal Occupational and Environmental Medicine, the findings were most prevalent in women who were overweight or obese, or over the age of 37 years old. However, researchers aren’t sure why or how jobs that require heavy lifting can negatively impact a woman’s egg reserves. Yet they do suspect that the fertility issues associated with working non-day shifts may stem from a disruption in a woman’s circadian rhythm. Such a disruption could affect a sizable amount of women, since 2004 data from the Bureau of Labor Statistics found 12.4 percent of women working full-time operate on alternative shifts (nights, weekends, evenings). Further research is needed to see if there are any work exposures a woman can avoid to protect her fertility, the study authors noted.