Article Text
Abstract
Objectives Pregnancy complications are common contributors to perinatal mortality and morbidity. Still, the cause(s) of gestational hypertensive disorders and diabetes are largely unknown. Some occupational exposures have been inconsistently associated with pregnancy complications, but exposure to whole-body vibrations (WBV) has been largely overlooked even though it has been associated with adverse birth outcomes. Therefore, the aim was to assess whether occupational WBV exposure during pregnancy is associated with pregnancy complications in a nationwide, prospective cohort study.
Methods The Fetal Air Pollution Exposure cohort was formed by merging multiple Swedish, national registers containing information on occupation during pregnancy and diagnosis codes, and includes all working women who gave birth between 1994 and 2014 (n=1 091 044). WBV exposure was derived from a job-exposure matrix and was divided into categories (0, 0.1–0.2, 0.3–0.4 and ≥0.5 m/s2). ORs with 95% CIs were calculated using logistic regression adjusted for potential confounders.
Results Among women working full time (n=646 490), we found increased risks of all pregnancy complications in the highest exposure group (≥0.5 m/s2), compared with the lowest. The adjusted ORs were 1.76 (95% CI 1.41 to 2.20), 1.55 (95% CI 1.26 to 1.91) and 1.62 (95% CI 1.07 to 2.46) for preeclampsia, gestational hypertension and gestational diabetes, respectively, and were similar in all sensitivity analyses. There were no clear associations for part-time workers.
Conclusions The results suggest that women should not be exposed to WBV at/above the action limit value of 0.5 m/s2 (European directive) continuously through pregnancy. However, these results need further confirmation.
- hygiene / occupational hygiene
- epidemiology
- female reproductive effects and adverse pregnancy outcomes
- vibration
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Footnotes
Contributors All authors contributed to the study conception and design. Data collection, management and analysis were performed by HP, FN, JS and HS. Funding was acquired by JS, HP, MA, LR and PG. The first draft of the manuscript was written by HS and all authors commented on all versions of the manuscript. All authors read and approved the final manuscript.
Funding The present project was funded by grant 2016-00902 to investigator Jenny Selander from Forte, the Swedish Research Council for Health, Working Life and Welfare.
Patient consent for publication Not required.
Ethics approval All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee (the Regional Ethical Review Board, Stockholm, Sweden, reference number: 2017/957-31/2) and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. Formal consent is not obligated in this register-based cohort study, instead, all the registries involved have performed a confidentiality control on the behalf of the study participants.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data may be obtained from a third party and are not publicly available. Data can be obtained through acquisition from Swedish registers. The data collection process is described in the method section of this paper. Data code for analysis in Stata can be obtained from the corresponding author upon request.