Objective To investigate whether there is a seasonal variation in the incidence of gestational diabetes mellitus (GDM).
Research design and methods This retrospective cohort study of 60 306 eligible South Australian live-born singletons during 2007–2011 recorded in the South Australian Perinatal Statistics Collection (SAPSC) examined the incidence of GDM in relation to estimated date of conception (eDoC). Fourier series analysis was used to model seasonal trends.
Results During the study period, 3632 (6.0%) women were diagnosed with GDM. Seasonal modeling showed a strong relation between GDM and eDoC (p<0.001). Unadjusted and adjusted models (adjusted for maternal age, body mass index (BMI), parity, ethnicity, socioeconomic status, and chronic hypertension) demonstrated the presence of a peak incidence occurring among pregnancies with eDoC in winter (June/July/August), with a trough for eDoc in summer (December/January/February). As this was a retrospective study, we could only use variables that had been collected as part of the routine registration system, the SAPSC.
Conclusions This study is the first population-based study to demonstrate a seasonal variation for GDM. Several maternal lifestyle and psychosocial factors associated with seasonality and GDM may be influential in the pathophysiologic mechanisms of GDM. Ambient temperature, physical activity, nutrient intake, and vitamin D levels may affect maternal physiology, and fetal and placental development at the cellular level and contribute to the development of GDM. The mechanisms underlying these possible associations are not fully understood and warrant further investigation.
- Gestational Diabetes Mellitus
- Pregnancy Medical Disorders
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Contributors PEV and CTR are the guarantors of the work as a whole, including study design, access to the data, and the decision to submit and publish the manuscript. All authors have seen and approved the final version of this manuscript on submission. PEV has designed and executed the study, contributed to data analyses, interpreted the data, wrote the final manuscript and the critical discussion. GT contributed to study execution, carried out all necessary data analyses, and participated in interpretation of the data. WS contributed to study execution, data interpretation, and provided significant revisions. JJHME contributed to manuscript drafting and provided significant revisions. CTR participated in interpretation of the data, contributed in the critical discussion, and provided significant revisions. GAD contributed to study design, data interpretation, manuscript drafting, and critical discussion.
Funding PEV holds a PhD scholarship from the University of Groningen, Groningen, The Netherlands and a stipend from the Robinson Research Institute, University of Adelaide, Adelaide, Australia. CTR is a Senior Research Fellow (GNT1020749) at National Health and Medical Research Council of Australia (NHMRC) and is supported by a NHMRC project grant (GNT1059120).
Competing interests None declared.
Ethics approval Human Research Ethics Committee of the South Australian Department of Health.
Provenance and peer review Not commissioned; internally peer reviewed.
Data sharing statement The data were made available for this research by the South Australian Government Health Department, under ethics approval with strict no disclosure provisions for individual health records. Those wanting access to patient records for research purposes are advised to approach Dr Wendy Scheil, Pregnancy Outcome Unit, Epidemiology Branch, Department of Health, 11 Hindmarsh Square, Adelaide, South Australia (email Wendy.Scheil@ sa.gov.au, phone +61882266357).
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