Adverse pregnancy outcomes in women with type 1 diabetes: A nationwide, population‐based study, 1999–2021

INTRODUCTION: For the total population and for groups of non-immigrant and immigrant women, we examined the associations of maternal type 1 diabetes with adverse pregnancy outcomes among women who gave birth in Norway from 1999 to 2021. Further, we examined the associations between the two time periods 1999-2014 and 2015-2021 and adverse pregnancy outcomes, and whether these associations differed in women with or without type 1 diabetes. MATERIAL AND METHODS: In this nationwide population-based observational study, with data from the Medical Birth Registry of Norway and Statistics Norway 1999-2021, we used logistic regression to examine the associations between type 1 diabetes and adverse pregnancy outcomes. Moreover, differences in ORs for adverse pregnancy outcomes between those with and without type 1 diabetes were compared for the two time periods 1999-2014 and 2015-2021 using interaction analyses. Analyses were performed for the overall population, as well as separately for non-immigrant (n = 964 542) and immigrant women (n = 257 409). RESULTS: Women with type 1 diabetes (non-immigrant women n = 5067 and immigrant women n = 619) had higher ORs for almost all adverse pregnancy outcomes (OR 1.41-11.04) compared to women without diabetes in the period 1999-2021. In the time period 2015-2021, compared to 1999-2014, women with type 1 diabetes had a notably reduced OR of congenital malformations compared to those without diabetes (p interaction: 0.006). Immigrant women with type 1 diabetes had a higher OR in 2015-2021 vs. 1999-2014 of having large for gestational age infants (p interaction: 0.003). CONCLUSIONS: Women with type 1 diabetes had higher odds of most of the examined adverse pregnancy outcomes, though improvements were observed from 2015 to 2021 compared to 1999-2014, particularly a reduction in congenital malformations. In contrast, immigrants had higher odds of large for gestational age. These findings highlight the continued need for targeted interventions to reduce the burden of adverse outcomes in all women with type 1 diabetes.