Shift Work and Heavy Lifting Linked to Reduced Fertility

A new study has shown that jobs which require heavy lifting on a regular basis could reduce a woman’s fertility, more so if a woman is overweight. Working anti social hours, i.e working late at night, in the evenings and on shifts that keep changing can also decrease fertility.

The study, which was conducted by a team of Harvard researchers, was published by the Occupational and Environmental Medicine journal. The team study more than 470 women who were undergoing fertility treatment. Women who were participating in heavy lifting and moving had 8.8 percent fewer total eggs and 14.1 percent fewer mature eggs compared to women who had never done this sort of work.

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, the lead author of the study, in a statement.

However, the team insists that the results imply a correlation and not necessarily a causation between heavy lifting and reduced fertility. In addition, the women who underwent the study were all in need of fertility treatment. Thus they were not sure whether a similar correlation would be found in women who were not in need of the treatment.

Also experts pointed out that the sample size was too small to rule out other reasons for reduced fertility.

Testosterone was another  unaccounted factor. "In the study, no effort was made to address confounding by testosterone levels in those women. A physically stronger woman is more likely to undertake heavy lifting but would also be implicitly less fertile," said Alastair Sutcliffe, professor of pediatrics at University College London in the UK.

These findings have clinical implications, as women with fewer mature oocytes would have fewer eggs which are capable of developing into healthy embryos, said one of the authors of the study. 

So women who wish to start a family might think about the implications of the study and try and avoid this kind of work, said Professor Darren Griffin of the University of Kent.

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