Seasonality of gestational diabetes mellitus: a South Australian population study

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