A new study at Harvard University shows that women who worked nightshifts and whose jobs involved heavy lifting had fewer eggs.

Researchers at Harvard University found that women who worked nightshifts and whose jobs involved heavy lifting had fewer eggs than their “day-shift” counterparts.

The Study

The researchers followed 500 women who were seeking fertility treatment and found that those who worked nightshifts and were heavy weight lifters at their job had lower fertility.

Fertility was measured based on the number of eggs produced by the women when their ovaries were stimulated during IVF.

The study found that women who worked day shifts produced an average of 11.2 eggs per session, where as their night-shift counterparts had 8.7 eggs per session- a 28 percent decrease.

Women whose jobs involved heavy lifting were also found to have 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.

Why Does That Happen?

Researchers suggest that nightshifts may be disrupting women’s circadian rhythm, which would therefore prevent eggs from developing or maturing.

According to Professor Alastair Sutcliffe, Professor of Paediatrics at the University of College London: “Human beings like light. 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.”

Professor Darren Griffin, Professor of Genetics, University of Kent, said: “Women who are trying to start a family may with to 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.”