The association between interpregnancy interval and gestational diabetes mellitus: A nationwide register-based study in Finland.

Objective: Previous results on the association between interpregnancy interval (IPI) and gestational diabetes mellitus (GDM) have been contradictory. Hence, the aim of this study was to examine the association between IPI and GDM using high-quality nationwide register data.

Methods: All women with first and second pregnancies during our study period from the National Medical Birth Register during 2004-2018 were considered. A logistic regression model was used to assess the association between the length of the IPI and development of the GDM in the second pregnancy. Women were divided into three groups based on the length of the IPI: short IPI (0-11 months), normal IPI (12-47 months), and long IPI (48+ months). Adjusted odds ratios (aOR) with 95% CI were compared between the groups.

Results: A total of 47 078 women were included in the study. We found no evidence of difference when women with short IPI were compared with women with normal IPI (aOR 0.99, 95% CI 0.93-1.05). Women with long IPI had increased odds for the development of GDM when compared with women with normal IPI (aOR 1.28, 95% CI 1.19-1.38). In the logistic regression model for continuous IPI, the total odds for the development of GDM increased as the IPI increased (aOR 1.05 per year, 95% CI 1.03-1.06).

Conclusion: The odds for the development of GDM increased as the IPI increased. This study's results serve as a clarion call for proactive measures in GDM prevention. Moreover, they advocate for intensified investigation into the underlying factors contributing to GDM among women with extended IPI. It is imperative that these insights inform both clinical practice and further research agendas, as we strive to safeguard maternal health and well-being.