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Pregnant women who work nights may have a greater risk of miscarriage

Women who work two or more night shifts in one week may have a greater risk of miscarriage the following week

Date:
March 25, 2019
Source:
BMJ
Summary:
Working two or more night shifts in a week may increase a pregnant woman's risk of miscarriage the following week by around a third, shows a prospective study.
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Working two or more night shifts in a week may increase a pregnant woman's risk of miscarriage the following week by around a third, shows a prospective study published online in Occupational & Environmental Medicine.

Previous studies have suggested that pregnant women face a greater risk of miscarriage if they work night shifts, but they have been based on self-reported shift work and have not quantified the level of increased risk or the amount of shift work involved.

For this study the authors accessed payroll data on 22,744 pregnant women working in public services, mainly hospitals, in Denmark, and linked that with data from Danish national registers on births and admissions to hospital for miscarriage to determine how the risk of miscarriage between weeks 4-22 of pregnancy was influenced by night work.

Overall 377,896 pregnancy weeks were included -- an average of 19.7 weeks per woman.

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.

And the risk of miscarriage increased with the number of night shifts worked per week and also by numbers of consecutive night shifts.

The association between night work and the risk of miscarriages was stronger after pregnancy week 8. "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 authors say.

This is an observational study, and as such, can't establish cause, and the authors point out that data on miscarriages, particularly early miscarriages, were incomplete.

But, as around 14% of women in Europe report working at night at least once a month, the findings have relevance for working pregnant women as well as their employers, physicians and midwives, they emphasise. "Moreover, the results could have implications for national occupational health regulations."

In terms of the underlying mechanism responsible for the association, women working night shifts are exposed to light at night which disrupts their circadian rhythm and decreases the release of melatonin. Melatonin has been shown to be important in maintaining a successful pregnancy, possibly by preserving the function of the placenta.


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Materials provided by BMJ. Note: Content may be edited for style and length.


Journal Reference:

  1. Luise Moelenberg Begtrup, Ina Olmer Specht, Paula Edeusa Cristina Hammer, Esben Meulengracht Flachs, Anne Helene Garde, Johnni Hansen, Åse Marie Hansen, Henrik Albert Kolstad, Ann Dyreborg Larsen, Jens Peter Bonde. Night work and miscarriage: a Danish nationwide register-based cohort study. Occupational and Environmental Medicine, 2019 DOI: 10.1136/oemed-2018-105592

Cite This Page:

BMJ. "Pregnant women who work nights may have a greater risk of miscarriage." ScienceDaily. ScienceDaily, 25 March 2019. <www.sciencedaily.com/releases/2019/03/190325184115.htm>.
BMJ. (2019, March 25). Pregnant women who work nights may have a greater risk of miscarriage. ScienceDaily. Retrieved March 28, 2024 from www.sciencedaily.com/releases/2019/03/190325184115.htm
BMJ. "Pregnant women who work nights may have a greater risk of miscarriage." ScienceDaily. www.sciencedaily.com/releases/2019/03/190325184115.htm (accessed March 28, 2024).

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