Abstract Body

Background: Our aim was to compare risk factors associated with adverse pregnancy outcomes in women with type 1 and type 2 diabetes.

Methods: We included 17,375 pregnancies in 15,290 women with diabetes in a population-based cohort study across 172 maternity clinics. Obstetric complications (preterm delivery, large birthweight) and adverse pregnancy outcomes (congenital anomaly, stillbirth, neonatal death) were obtained for pregnancies during 2014-2018. We assessed associations between modifiable (glycaemia, obesity, clinic) and non-modifiable risk factors (age, deprivation, ethnicity) with pregnancy outcomes.

Results: Of 17,375 pregnancies, 8,690 (50.0%) were in women with type 1 and 8,685 (50.0%) in women with type 2 diabetes. The rates of preterm delivery (42.5% type 1, 23.4% type 2), and large birthweight (52.2% type 1, 26.2% type 2) were higher in type 1 diabetes (p<0.001). The prevalence of congenital anomaly (44.8/1000 type 1, 40.5/1000 type 2; p=0.175), and stillbirth (10.4/1000 type 1, 13.5/1000 type 2; p=0.072) did not differ but neonatal death rates (7.4/1000 type 1, 11.2/1000 type 2; p=0.013) were higher in type 2 diabetes. Independent risk factors for perinatal death were third trimester HbA1c > 48mmol/mol (OR 3.06, 95% CI 2.16 to 4.33), living in the highest deprivation quintile (OR 2.29 95% CI 1.16 to 4.52) and having type 2 diabetes (OR 1.65 95% CI 1.18 to 2.31). Variations in glycaemia and large birthweight were associated with maternal characteristics (diabetes duration, deprivation, BMI) without substantial differences between clinics.

Interpretation: No clinics were achieving appreciably better outcomes, suggesting that healthcare system changes are needed across all clinics.