Gestational diabetes and maternal third-trimester blood count

OBJECTIVE: To examine the effect of gestational diabetes mellitus (GDM) in the third trimester on the maternal blood count in nonanemic women with singleton pregnancies. STUDY DESIGN: In a prospective, observational study, consecutive women without preexisting anemia or hemoglobinopathies, endocrine disorders or diabetes were recruited for blood sampling for complete blood count at 28-30 weeks' gestation, when they were screened for GDM, and again at 36-38 weeks' gestation. The management of pregnancy or GDM was not influenced by the study. After delivery, the blood count results were compared between women with and without GDM. RESULTS: Of the 462 women recruited, 64 (13.8%) were diagnosed with GDM. This group had similar blood counts at 28-30 weeks but significantly higher hemoglobin, red cell count and hematocrit and lower white cell count at 36-38 weeks as compared with the controls. Except for the lower platelet count, these differences appeared to represent an accentuation of the gestation-related changes that were found in the controls. CONCLUSION: The development of GDM in the third trimester is associated with significant changes in blood counts beyond the effect of advancing gestation alone, probably related to the pathologic effect of diabetes.