Pregnant women who work overnight shift work or longer hours have a higher potential of preterm delivery and miscarriage, according to a report from University of Alberta researchers. 

The year-long study appeared in this month's issue of the American Journal of Obstetrics and Gynecology

Researchers looked at data from 62 independent studies from 33 countries, which looked at 196,989 different women, dating as far back as 1960.

Analysis of the numbers revealed that pregnant women who worked a fixed night shift were 21 per cent more likely to experience preterm delivery and were at a 23 per cent higher risk of miscarriage than pregnant women who worked a regular day shift.

The study also showed that a woman who works more than 40 hours a week while pregnant has a 21 per cent higher chance of going into preterm delivery and a 38 per cent higher risk of miscarriage.

"We were able to see that there’s an association between work schedule and increased risk of having an adverse pregnancy outcome," U of A researcher Margie Davenport said.

Margie Davenport

Nurses reaction 

Haley Ives is a nurse at the Royal Alexandra Hospital. Pregnant now with her second child and currently on maternity leave, she said she was aware of the risks her profession’s hours might pose to her pregnancy the first time around.

"At 35 weeks, although I felt like maybe I could keep going, I was like ‘that’s enough’. I don’t need a preterm baby," said Haley Ives, a hospital nurse. 

Haley Ives

David Harrigan with the United Nurses of Alberta told CTV News Edmonton that they’re not surprised by the findings.

“We’ve tried to build into our collective agreement some protections to at least minimize the dangers involved," Harrigan said.

"What we’ve tried to do is match the concerns that we have about shift work with the reality that it’s just unavoidable in some industries."

David Harrigan

Next steps

Davenport said that it’s difficult to link a direct cause for the study’s findings and hopes further research will change that.

“There needs to be a lot more research done. We really have to drive that research so that we can put policies in place to be able to help pregnant women,” she said.

The study, which was funded by the Government of Alberta Occupational Health and Safety Futures Grant, will follow up with new research looking at how the type of work pregnant women engage in affects maternal and fetal health.