Women should ‘stick to the day job’ if they want to have children after a study found those who work nightshift have fewer eggs.
Researchers at Harvard University followed 500 women who were seeking fertility treatment at Massachusetts General Hospital and found those who worked unsociable hours, or whose jobs involved heavy lifting, were less fertile.
The findings were based on the number of eggs produced by women when their ovaries were stimulated during IVF.
Women who worked day shift produced an average of 11.2 eggs per session compared with 8.7 percent for nightshift workers, a decrease of 28 percent.
Likewise women whose jobs involved heavy lifting had 14 percent fewer eggs.
“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 lead author Dr Lidia Mínguez-Alarcón.
The researchers believe that nightshift may disrupt circadian rhythm and prevent eggs from developing or maturing.
Prof Alastair Sutcliffe, Professor of Paediatrics at University College London said that women who were trying to become pregnant should try and avoid night work and heavy lifting.
“Human beings like light,” he said. “When sunlight hits our retinae, the serotonin ‘happy hormone’ goes up instantly in the brain. Hence we love sunny winter days, but not dank overcast ones.
“So shift work is not a biologically good way to work and folks who have to do this are known to get many ill health risks such hypertension.
“So what does this study mean? If trying to optimise fertility, stick to the day job and leave the lifting to their partner.”
The new research was published in the journal Occupational and Environmental Medicine.
Professor Darren Griffin, Professor of Genetics, University of Kent, added: “Women who are trying to start a family may take the study into account, perhaps avoiding heavy lifting and unsociable work hours as much as is possible during this time, especially if they are not falling pregnant within the first year of trying.”