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.