Impact of sunshine on the risk of gestational diabetes mellitus in primiparous women

ABSTRACT

There is a lack of data about the influence of sunshine hours on the prevalence for gestational diabetes mellitus (GDM). The aim of this study was to evaluate whether the prevalence of GDM varied according to hours of daily sunshine during the first trimester. The study cohort (N = 6189) consists of all primiparous women with a Finnish background who delivered between 2009 and 2015 living in Vantaa city, Finland. Data on births and maternal characteristics were obtained from National Health Registers. Data on sunshine hours were obtained from the Finnish Meteorological Institute. Individual daily sunshine hours during the first trimester of pregnancy were calculated for each woman. Diagnosis of GDM was based on a standard 75-g 2-h glucose tolerance test (OGTT). No relationship was observed between month of conception and GDM. Daily sunshine hours during the first trimester and GDM showed a U-shaped association (adjusted p-value 0.019). In OGTT, a U-shaped association was observed between 0-h glucose value and daily sunshine hours during the first trimester (p = 0.039) as well as with the 1-h glucose value (p = 0.012), respectively. In primiparous women daily sunshine hours during the first trimester showed a U-shaped association with the prevalence of GDM independent of pre-pregnancy risk factors.

Abbreviations: BMI: body mass index; GDM: gestational diabetes mellitus; OGTT: standard 75 g 2-h glucose tolerance test; SD: standard deviation

KEYWORDS:

• Body mass index
• early pregnancy
• gestational diabetes mellitus
• glucose tolerance test
• sunshine

Acknowledgments

We thank Jalmari Kautiainen for excellent statistical advice.

Disclosure statement

No potential conflict of interest was reported by the authors.

Ethical approval

The ethics committee of the Hospital District of Helsinki and Uusimaa, Finland (356/13/03/03/2015, 2 November 2015), and the health authority of the city of Vantaa, Finland, have approved the study. National Institute for Health and Welfare (THL) and Statistics Finland have given permission to use register data in the study.

Informed consents were not required because this is an observational register-based cohort study and no study participants were contacted.

Availability of data and materials

Data cannot be shared for both legal and ethical reasons. Data from the National Institute for Health and Welfare, Statistics Finland, and the Finnish Social Insurance Institution can only be used for the purpose stated in the license granted, scientific research on society by the license applicant, and can therefore not be shared with third parties.

Additional information

Funding

This study was funded by Research Foundation for Primary Health Care, Finland. The funding source had no role for conducting the research or preparation for the article.