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Night Shift and Risk of Spontaneous Abortion: Critically Appraised Topic

August 2020


Background: Spontaneous abortion (SAB) is defined as fetal loss before 20 weeks gestation. Eighty percent of spontaneous abortions are reported within the first 12 weeks from the female’s last menstrual period. At least half of spontaneous abortions occur because of fetal chromosomal abnormalities. Research regarding environmental factors and other potential risk factors of SAB are underway at this time.

Methods: An exhaustive search was conducted of MEDLINE-Pubmed, EBSCO Academic Search Premier, and Web of Science using the keywords “miscarriage”, “spontaneous abortion”, “night shift”, “swing shift”, “night work”, and “spontaneous abortion risk”. A risk of bias assessment was performed.

Results: The 3 eligible articles were cohort studies taking place in the United States and Denmark. The first study included 22 744 participants that were found via the Danish Working Hour Database (DWHD). Spontaneous abortions were documented from data found in the Danish National Patient Register (DNPR). The second study identified 33 694 Danish women that were found via the Danish National Birth Cohort (DNBC). Data regarding shifts worked and SAB was gathered via telephone interviews. The third study evaluated data from The Nurses’ Health Study II, a prospective cohort study in which night shift work and SAB were recorded via a questionnaire. All 3 studies suggested an increased risk of miscarriage with night shift work.

Conclusion: Working night shift during pregnancy may increase the risk of spontaneous abortion. This research has implications for all pregnant women working night shifts and should prompt a possible change in occupational health regulations.

Keywords: Spontaneous abortion, night shift, night work, nurse


This is a metadata only record.