Obstetric and Perinatal Outcomes in Type 1 Diabetic Pregnancies: A large, population-based study

OBJECTIVE: To perform comparative analyses of obstetric and perinatal outcomes between type 1 diabetic pregnancies and the general obstetric population in Sweden between 1991 and 2003. RESEARCH DESIGN AND METHODS: This was a population-based study. Data were obtained from the Medical Birth Registry, covering >98% of all pregnancies in Sweden. A total of 5,089 type 1 diabetic pregnancies and 1,260,207 control pregnancies were included. Odds ratios (ORs) were adjusted for group differences in maternal age, parity, BMI, chronic hypertensive disease, smoking habits, and ethnicity. RESULTS: In type 1 diabetes, preeclampsia was significantly more frequent (OR 4.47 [3.77–5.31]) as was delivery by cesarean section (5.31 [4.97–5.69]) compared with results for the general population. Stillbirth (3.34 [2.46–4.55]), perinatal mortality (3.29 [2.50–4.33]), and major malformations (2.50 [2.13–2.94]) were more common in type 1 diabetic than in control pregnancies. The risk of very preterm birth (<32 gestational weeks) was also higher among type 1 diabetic women (3.08 [2.45–3.87]). The incidence of fetal macrosomia (birth weight ≥2 SD above the mean) was increased in the diabetic group (11.45 [10.61–12.36]). CONCLUSIONS: Type 1 diabetes in pregnancy is still associated with considerably increased rates of adverse obstetric and perinatal outcomes. The eightfold increased risk for fetal macrosomia in type 1 diabetic pregnancies is unexpected and warrants further investigation.