Shift work, long working hours and preterm birth: a systematic review and meta-analysis

  • M. J. G. J. van MelickEmail author
  • M. D. M. van Beukering
  • B. W. Mol
  • M. H. W. Frings-Dresen
  • C. T. J. Hulshof
Review Article



Specific physical activities or working conditions are suspected for increasing the risk of preterm birth (PTB). The aim of this meta-analysis is to review and summarize the pre-existing evidence on the effect of shift work or long working hours on the risk of PTB.


We conducted a systematic search in MEDLINE and EMBASE (1990–2013) for observational and intervention studies with original data. We only included articles that met our specific criteria for language, exposure, outcome, data collection and original data that were of at least of moderate quality. The data of the included studies were pooled.


Eight high-quality studies and eight moderate-quality studies were included in the meta-analysis. In these studies, no clear or statistically significant relationship between shift work and PTB was found. The summary estimate OR for performing shift work during pregnancy and the risk of PTB were 1.04 (95 % CI 0.90–1.20). For long working hours during pregnancy, the summary estimate OR was 1.25 (95 % CI 1.01–1.54), indicating a marginally statistically significant relationship but an only slightly elevated risk.


Although in many of the included studies a positive association between long working hours and PTB was seen this did reach only marginal statistical significance. In the studies included in this review, working in shifts or in night shifts during pregnancy was not significantly associated with an increased risk for PTB. For both risk factors, due to the lack of high-quality studies focusing on the risks per trimester, in particular the third trimester, a firm conclusion about an association cannot be stated.


Preterm birth Shift work Working hours Meta-analysis 



The authors wish to thank Dr. J.H.A.M. Verbeek (Finnish Institute of Occupational Health, Kuopio, Finland) for his help with the meta-analysis.

Conflict of interest

The authors declare that they have no conflict of interest.


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Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  • M. J. G. J. van Melick
    • 1
    Email author
  • M. D. M. van Beukering
    • 2
  • B. W. Mol
    • 3
  • M. H. W. Frings-Dresen
    • 4
  • C. T. J. Hulshof
    • 4
  1. 1.Maastricht University Medical CentreDepartment of Obstetrics and GynaecologyMaastrichtThe Netherlands
  2. 2.DNV GL, Department of Occupational Health and Safety ServiceArnhemThe Netherlands
  3. 3.The Robinson Institute, School of Paediatrics and Reproductive Health University of AdelaideAdelaideAustralia
  4. 4.Academic Medical Center, Coronel Institute of Occupational Health, University of AmsterdamAmsterdamThe Netherlands

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