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Original research
Night shift work undertaken by women and fertility treatment interact to increase prevalence of urogenital anomalies in children
  1. Renae C Fernandez1,2,3,
  2. Vivienne M Moore2,3,4,
  3. Kristyn J Willson2,3,
  4. Michael Davies1,2
  1. 1Adelaide Medical School, The University of Adelaide Faculty of Health and Medical Sciences, Adelaide, South Australia, Australia
  2. 2The University of Adelaide Robinson Research Institute, North Adelaide, South Australia, Australia
  3. 3School of Public Health, The University of Adelaide Faculty of Health and Medical Sciences, Adelaide, South Australia, Australia
  4. 4Fay Gale Centre for Research on Gender, The University of Adelaide, Adelaide, South Australia, Australia
  1. Correspondence to Dr Renae C Fernandez, Adelaide Medical School, The University of Adelaide Faculty of Health and Medical Sciences, Adelaide, South Australia 5005, Australia; renae.fernandez{at}adelaide.edu.au

Abstract

Objective To investigate the role of maternal night shift work in occurrence of urogenital anomalies in offspring, considering a possible interaction with mode of conception.

Methods A population-based cohort comprising births in South Australia (1986–2002) was produced via linkage of fertility clinic records, perinatal and birth defects data. This study concerned first births to women in paid employment (n=98 103). Potential exposure to night shift was imputed by applying a job-exposure matrix to recorded occupation. Associations were examined using logistic regression, first for nurses and other night shift workers separately, then combined. An interaction term for night shift work and mode of conception was included in all models, while adjusting for covariates.

Results Associations were similar for nurses and other night shift workers, although only statistically significant for the former when considered separately. A multiplicative interaction was supported: for natural conceptions, maternal night shift work was not associated with offspring urogenital anomalies (OR=0.99, 95% CI 0.84 to 1.15); where a birth arose from fertility treatment, urogenital anomalies were significantly higher among births to all night shift workers compared with day workers (OR=2.07, 95% CI 1.20 to 3.55). This was not due to differences in the type of fertility treatment received.

Conclusions Women in occupations that probably involved night shift did not have offspring with increased prevalence of urogenital anomalies if they conceived naturally. When night shift workers conceived with fertility treatment, the prevalence of urogenital anomalies was elevated. Possibly these women had the greatest exposure to night shift work, or least tolerance for this work schedule, or heightened sensitivity to hormonal aspects of fertility treatment.

  • fertility
  • shift work schedule
  • pregnancy outcome
  • congenital abnormalities
  • epidemiology

Data availability statement

The authors do not have permission to share the data as they were provided specifically for the scope of research as approved by the ethics committees. Requests to access these datasets should be directed to https://www.santdatalink.org.au.

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Data availability statement

The authors do not have permission to share the data as they were provided specifically for the scope of research as approved by the ethics committees. Requests to access these datasets should be directed to https://www.santdatalink.org.au.

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Footnotes

  • Contributors RCF, VMM and MD designed the study; RCF carried out statistical analyses; KJW provided statistical expertise; RCF and VMM drafted the manuscript; all authors interpreted the study results and contributed with manuscript revisions and approved the final version of the manuscript.

  • Funding RCF was supported by an Australian Postgraduate Award from the Commonwealth Government through the University of Adelaide and a Robinson Research Institute Lloyd Cox Career Development Fellowship. MD and development of the cohort has been supported by grants from the NHMRC (349475, 349548, 453556 and 465455) and the Australian Research Council (FT100101018).

  • Disclaimer The funding sources had no involvement in the conduct of the research.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.

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