Gestational diabetes in primiparous women-impact of age and adiposity: a register-based cohort study.

Introduction: Data on risk factors for gestational diabetes mellitus (GDM) in primiparous women is limited. The aim of this study was to assess the prevalence of GDM and simultaneously evaluate the impact of age and adiposity in primiparous women at risk of GDM risk.

Material And Methods: This observational register-based cohort study from the city of Vantaa, Finland, included all 7750 primiparous women giving birth between 2009 and 2015 without previously diagnosed diabetes mellitus.

Results: In primiparous women the prevalence of GDM was 16.5% and mean age was 28.2 years (5.2 SD). Primiparous women aged ≥35 years had a significantly higher risk for GDM than women aged <25 years [odds ratio (OR) 2.67, 95% confidence interval (CI) 2.13-3.34]. Primiparous women with a pre-pregnancy body mass index (BMI) ≥30.0 kg/m had a significantly higher risk for GDM than women with a pre-pregnancy BMI <25 kg/m (OR 5.36, 95% CI 4.53-6.36). The risk of developing GDM showed an increasing trend with increasing age in all BMI categories except the category BMI ≥35 kg/m . Normal weight women (BMI 20.0-24.9 kg/m ) aged 40 years had a significantly higher risk for GDM than normal weight women aged 28 years (OR 1.48, 95% CI 1.01-2.19).

Conclusions: The prevalence of GDM is high in primiparous women. Both age and degree of adiposity influenced the risk for GDM. To reduce GDM risk, adiposity should be prevented already in childhood and primiparity should be encouraged at a younger age.