Detection of pregnancies with high risk of fetal macrosomia among women with gestational diabetes mellitus

OBJECTIVE: To compare the frequency of fetal macrosomia and Erb's palsy in two groups of women with gestational diabetes mellitus (GDM) and in healthy controls. DESIGN: Retrospective clinical study of women with GDM. SETTING: Pregnant women in Greater Helsinki area. POPULATION: Nine hundred and five pregnancies and newborn infants of women with GDM and 805 non-diabetic controls. METHODS: GDM was diagnosed by a 2-hour oral glucose tolerance test (OGTT) among women with risk factors for GDM. The treatment of GDM was resolved by a 24-hour glucose profile obtained after 2 or 3 abnormal glucose values in the OGTT. Patients with a history of insulin-treated GDM in a previous pregnancy and those with a fasting glucose over 6 mmol/l underwent a 24-h glucose profile directly without a preceding OGTT. MAIN OUTCOME MEASURES: Fetal macrosomia, defined as a birth weight (adjusted for sex and gestational age) of >2.0 SD above the mean of a Finnish standard population. Erb's palsy. RESULTS: 385 women (42.5%) were treated with insulin and diet and 520 (57.5%) with diet only. Macrosomia occurred more often in the insulin-treated group (18.2%, p<0.001) compared with the diet-treated group (4.4%) and the controls (2.2%). The rate of Erb's palsy was 2.7% in the insulin-treated group, 2.4% in the diet-treated group, compared with 0.3% in the controls (p<0.001). CONCLUSION: The 24-hour glucose profile performed after the diagnosis of GDM clearly distinguishes between low-risk (diet-treated) and high-risk (insulin-treated) for fetal macrosomia in GDM pregnancies.