Women who more two night shifts or more may have a higher risk of miscarriage.
Working more than one night shift a week may increase a pregnant woman’s risk of having a miscarriage the following week by around a third, according to a new study.
The study to be published in Occupational & Environmental Medicine is based on payroll data on 22,744 pregnant women working in public services in Denmark and information from Danish national registers on births and admissions to hospital for miscarriage. It looked at the links between night work and risk of miscarriage between week four and week 22 of pregnancy.
It found that after week eight of pregnancy, women who had worked two or more night shifts the previous week had a 32% higher risk of miscarriage compared with women who had not worked any night shifts that week. The study also showed that the risk of miscarriage rose if more night shifts were worked and if women worked a number of consecutive night shifts.
The authors write: “This may be explained by the decline in the proportion of chromosomally abnormal fetuses with gestational age, which makes an association with environmental exposure more easily detectable among later miscarriages.”
The link between night shifts and miscarriage is thought to be due to the fact that women working night shifts are exposed to light at night which disrupts their circadian rhythms and decreases the release of melatonin. Melatonin has been linked to successful pregnancies and is thought to preserve the function of the placenta.