Single abnormal value on 3-hour oral glucose tolerance test during pregnancy is associated with adverse maternal and neonatal outcomes: a systematic review and metaanalysis.

OBJECTIVE DATA: The purpose of this study was to determine whether women with 1 abnormal value on 3-hour 100-g oral glucose tolerance test are at an increased risk for adverse pregnancy outcomes.

STUDY: Gestational diabetes mellitus is diagnosed by a 2-step method, with a 3-hour, 100-g oral glucose tolerance test that is reserved for women with an abnormal 1-hour, 50-g glucose challenge test. Although the increased maternal-fetal morbidity with gestational diabetes mellitus is well established, controversy remains about the risk that is associated with an isolated abnormal value during a 3-hour, 100-g oral glucose tolerance test.

STUDY APPRAISAL AND SYNTHESIS METHODS: Prospective and retrospective studies that evaluated the maternal and perinatal impact of 1 abnormal glucose value during a 3-hour, 100-g oral glucose tolerance test were identified with the use of computerized databases. Data were extracted and quantitative analyses were performed.

RESULTS: Twenty-five studies (7 prospective and 18 retrospective) that met criteria for metaanalysis included 4466 women with 1 abnormal glucose value on oral glucose tolerance test. Patients with 1 abnormal glucose value had significantly worse pregnancy outcomes compared with women with zero abnormal values with the following pooled odds ratios: macrosomia, 1.59 (95% confidence interval, 1.16-2.19); large for gestational age, 1.38 (95% confidence interval, 1.09-1.76); increased mean birthweight, 44.5 g (95% confidence interval, 8.10-80.80 g); neonatal hypoglycemia, 1.88 (95% confidence interval, 1.05-3.38); total cesarean delivery, 1.69 (95% confidence interval, 1.40-2.05); pregnancy-induced hypertension, 1.55 (95% confidence interval, 1.31-1.83), and Apgar score of <7 at 5 minutes, 6.10 (95% confidence interval, 2.65-14.02). There was also an increase in neonatal intensive care unit admission and respiratory distress syndrome. Similar results were seen that compared 1 abnormal glucose value to a population with a normal 1-hour 50-g glucose challenge test (normal glucose screen). With the exception of birthweight, outcomes of patients with 1 abnormal glucose value were similar to outcomes of patients with gestational diabetes mellitus.

CONCLUSION: Women with 1 abnormal value on 3-hour, 100-g oral glucose tolerance test have a significantly increased risk for poor outcomes comparable with women who have gestational diabetes mellitus.