Temporal Trends in Pregnancy Outcomes Among Parents With Type 1 Diabetes: A Nationwide Register‐Based Study

OBJECTIVE: To assess temporal trends in outcomes of pregnancies with maternal or paternal type 1 diabetes compared to the general population. DESIGN: Register-based study. SETTING: Denmark. POPULATION: 1 551 893 pregnancies from 1997 to 2021, hereof 5478 with maternal and 8072 with paternal type 1 diabetes. METHODS: Crude and adjusted logistic regression analyses allowing for interaction between diabetes and time compared outcomes of pregnancies with maternal or paternal type 1 diabetes to the general population and evaluated temporal trends over a 25-year period. MAIN OUTCOME MEASURES: Hypertensive disorders of pregnancy, caesarean delivery, preterm delivery (< 37-week gestation), very preterm delivery (< 34-week gestation), large for gestational age (LGA) (birth weight > 90th percentile) and extreme LGA (birth weight > 97.5th percentile). RESULTS: We observed an increasing prevalence of maternal (0.3%-0.4%) and paternal (0.5%-0.6%) diabetes during the study period. From 1997-2001 to 2017-2021, pregnancies with maternal diabetes had decreasing odds of preterm delivery (aOR 0.62, 95% CI 0.51;0.74), very preterm delivery (aOR 0.62, 95% CI 0.44;0.87) and extreme LGA (aOR 0.73, 95% CI 0.61;0.88) but remained associated with higher odds of each considered pregnancy outcome in both first and last period (aOR 3.59-18.86) compared to the general population. Pregnancies exposed to paternal diabetes were comparable to the general population. CONCLUSIONS: Despite a decline in adverse outcomes in pregnancies with maternal type 1 diabetes over the last 25 years, the odds remain greatly increased. These findings support a predominant role of maternal diabetes management rather than parental diabetes genes for pregnancy outcomes.