Context: Pregnancy for women with type 1 or type 2 diabetes is a time of increased risk for both mother and baby. The Atlantic Diabetes in Pregnancy program provides coordinated, evidence-based care for women with diabetes in Ireland. Founded in 2005, the program now shares outcomes over its first decade in caring for pregnant women with diabetes.Objective: The objective was to assess improvements in clinical outcomes after the introduction of interventions.Design, Setting, Participants: We retrospectively examined 445 pregnancies in women with type 1 and type 2 diabetes and compared them over two timepoints, 2005-2009 and 2010-2014.Interventions: Interventions introduced over that time include: provision of combined antenatal/diabetes clinics, prepregnancy care, electronic data management, local clinical care guidelines, professional and patient education materials, an app, and a web site.Main Outcomes: Pregnancy outcomes were measured.Results: The introduction of the Atlantic Diabetes in Pregnancy program has been associated with a reduction in adverse neonatal outcomes. There has been a reduction in congenital malformations (5 to 1.8%; P = .04), stillbirths (2.3 vs 0.4%; P = .09), despite an upward trend in maternal age (mean age, 31.7 vs 33 years), obesity (29 vs 43%; body mass index >30 kg/m(2)), and excessive gestational weight gain (24 vs 38%; P = .002). These improvements in outcomes occur alongside an increase in attendance at prepregnancy care (23 to 49%; P = .001), use of folic acid (45 vs 71%; P = .001), and sustained improvement in glycemic control.Conclusions: Changing the process of clinical care delivery and utilizing evidence-based interventions in a pragmatic clinical setting improves pregnancy outcomes for women with pregestational diabetes. We now need to target optimization of maternal body mass index before pregnancy and put a greater focus on gestational weight gain through education and monitoring.