The impact of gestational diabetes mellitus on pregnancy outcome comparing different cut-off criteria for abnormal glucose tolerance

Objective. To examine pregnancy outcomes in relation to different categories of glucose tolerance during pregnancy. Design. Prospective observational cohort study. Setting. Patient recruitment and data collection were performed in four delivery departments in southern Sweden. Population. Women delivering during 2003-2005; 306 with gestational diabetes mellitus, 744 with gestational impaired glucose tolerance and 329 randomly selected controls. Methods. All women were offered a 75 g oral glucose tolerance test during pregnancy. On the basis of their capillary 2-hour plasma glucose concentrations, three groups were identified: gestational diabetes mellitus (>10.0 mmol/l), gestational impaired glucose tolerance (8.6-9.9 mmol/l) and controls (<8.6 mmol/l). Data for the groups were compared using a population-based database. Main outcome measures. Maternal and fetal outcomes. Results. For the gestational diabetes mellitus group, adjusted odds ratios (95% confidence intervals) for hypertensive disorders during pregnancy and induction of labor and emergency cesarean section were 2.7 (1.3-5.8), 3.1 (1.8-5.2) and 2.5 (1.5-4.4), respectively; and for Apgar score < 7 at 5 minutes, need for neonatal intensive care >1 day and large-for-gestational age infant were 9.6 (1.2-78.0), 5.2 (2.8-9.6) and 2.5 (1.3-5.1), respectively. The increases in odds ratios for the gestational impaired glucose tolerance group were less pronounced but still significant for hypertension during pregnancy, induction of labor, large-for-gestational age infant and use of neonatal intensive care >1 day, with odds ratios (95% confidence interval) 2.0 (1.0-4.1), 1.8 (1.1-3.0), 2.1 (1.1-3.9) and 2.1 (1.1-3.8), respectively. Conclusions. These data indicate that even limited degrees of maternal hyperglycemia may affect the outcome of pregnancy.