Pregnant women who work at least two night shifts in a week may increase their risk of miscarriage in the next seven days, a new European study finds.
Danish researchers led by Dr. Luise Moelenberg Begtrup, from the Department of Occupational and Environmental Medicine at Bispebjerg and Frederiksberg Hospital in Kobenhavn, analyzed data on nearly 23,000 pregnant women to learn how night work might affect the odds of miscarriage between the fourth and 22nd week of pregnancy.
After the eighth week, women who had worked two or more night shifts in the previous week had a 32 percent higher risk of miscarriage than those who had not worked any nights, the study found.
And the risk rose with the number of night shifts worked in a week and also by the number of consecutive ones, according to the study published online March 25 in the journal Occupational & Environmental Medicine.
The researchers said it's possible that exposure to light at night disrupts a woman's body clock and reduces the release of melatonin.
Melatonin has been shown to play an important role in a successful pregnancy, possibly by maintaining function of the placenta.
The study has limitations, the authors added. Because it was an observational study, it can't prove working night shifts caused an increased risk of miscarriage. In addition, data on miscarriages, especially early ones, were incomplete.
But 14 percent of women in Europe work at night at least once a month, so the findings are important for working mothers-to-be, their employers, physicians and midwives, according to the authors.
"Moreover, the results could have implications for national occupational health regulations," they said.
The March of Dimes has more on miscarriage.