New research suggests risk of miscarriage increases when pregnant women work night shifts

Our bodies are designed to sleep during the night and be awake during the day.

Millions of years of evolution later, and this is still the case. Our body temperature drops at night, preparing our bodies for rest, our hormones change throughout the day, all designed so to help us be awake and alert during daylight hours, and to wind down, feel tired and sleep during the night.

However, for some, their job and career require them to sometimes turn this upside down, by having to stay awake when the rest of the world sleeps, and go to bed when morning breaks and people normally get up to start their day.

Many researchers and medical experts have argued over the years that this isn't ideal for our health and bodies.

And now a new study has come out to add fuel to that fire by claiming that pregnant women who work at night two or more times in a week can increase their likelihood of miscarriage the following week.

“The study corroborates earlier findings that night work during pregnancy may confer an increased risk of miscarriage and it indicates a lowest observed threshold level of two night-shifts per week,” the authors of the study wrote. “The new knowledge has relevance for working pregnant women as well as their employers, physicians, and midwives. Moreover, the results could have implications for national occupational health regulations.”

Risks of the night shift

To see how working the night shift affected pregnant women’s likelihood of miscarrying, the researchers analyzed payroll data from over 22,000 pregnant women, the majority of whom worked in hospitals. The researchers also evaluated hospital records for women admitted because of miscarriage and birth records.

The study revealed that pregnant women who worked two or more night shifts in the same week were over 30 percent more likely to have a miscarriage by the following week.

The researchers found that women were most vulnerable to miscarriage due to night work during weeks four through 22 of pregnancy, though after week eight, the risk was the highest. Moreover, more consecutive night shifts -- and the greater number of night shifts worked in the same week -- increased the chances of miscarriage.

One such reason for the association between working nights and miscarriage is the lack of melatonin being produced because of the reversed schedule. The researchers suggest that working at night disrupts the body’s natural circadian rhythm, making the body produce less melatonin, which has been found to be necessary for a healthy pregnancy.