Background: For women with type 1 diabetes in pregnancy, the mainstay insulin management options are continuous subcutaneous insulin infusion and multiple daily injections. Existing studies have found either inconclusive, inconsistent, and occasionally contradictory results. Without clear evidence for clinicians, pregnancy outcomes of each insulin management option have not been evaluated in a large single-centre cohort.
Objective: To compare pregnancy outcomes in women with type 1 diabetes mellitus using multiple daily injections or continuous subcutaneous insulin infusion in pregnancy.
Study Design: Retrospective cohort study of pregnancies booked between January 2006 and December 2016, at the Royal Women’s Hospital, Melbourne, Australia; a large subspecialty tertiary hospital. The population included 298 singleton pregnancies reaching 20 weeks gestation of adult women with pre-existing type 1 diabetes mellitus using continuous subcutaneous insulin infusion or multiple daily injections. Outcomes of interest included obstetric and neonatal outcomes, and HbA1c values through pregnancy. Descriptive statistics analysed baseline maternal characteristics between groups. Multivariable logistic regression models were then developed from univariable logistic regression to compare selected pregnancy outcomes.
Results: Women with type 1 diabetes mellitus using continuous subcutaneous insulin infusion in pregnancy were at a higher risk of having a large-for-gestational age >90th centile neonate [adjusted odds ratio (aOR) 2.00, 95% confidence intervals (CI) 1.20-3.34], a large-for-gestational age >95th centile neonate [aOR 2.05, 95% CI 1.22-3.45], and preterm birth [aOR 1.80, 95% CI 1.04-3.03]. Specifically, no adverse outcomes associated with large-for-gestational age or preterm deliveries were observed in the continuous subcutaneous insulin infusion cohort, and all other maternal and neonatal outcomes were comparable. HbA1c values were similar between groups pre-conception and at each trimester.
Conclusion: Continuous subcutaneous insulin infusion use during pregnancy in women with type 1 diabetes mellitus is associated with an increased risk of large-for-gestational age and preterm neonates, without an accompanied increase in risk of adverse maternal or neonatal outcomes.