Abstract: Pregnancies complicated with diabetes mellitus including pre-gestational diabetes mellitus (PGDM) and gestational diabetes mellitus (GDM), are at risk of developing a number of serious obstetric complications as well as having long-term implications for the wellbeing of mother and infant. Glycated hemoglobin (HbA1c) may reflect glucose levels over the previous 2-3 months, and acts as one of the diagnostic criteria outside of pregnancy recently. Many studies had been carried through about the role of HbA1c in pregnancy, included how can HbA1c in different gestational weeks predict GDM subsequently and adverse pregnancy outcomes even postpartum diabetes risk, the difference of HbA1c levels in different races and the influence factors of HbA1c levels. Further, whether HbA1c level is various in different ethnical and the influence factors of HbA1c level had been investigated. Most authors believed that HbA1c, as a diagnostic indicator of GDM, is not highly sensitive and may increase the rate of missed diagnosis. HbA1c alone or in combination with more indicators is a powerful supplement in screening and diagnosis of GDM and can reduce the number of oral glucose tolerance test (OGTT). HbA1c levels at different time points during pregnancy may be correlated with pregnancy outcomes, and prenatal HbA1c levels are also of certain value in identifying high-risk GDM pregnant women who may progress to T2DM. On account of the cut-off value of HbA1c, the strategies of GDM screen and diagnosis with HbA1c are inconsistent, more researches are needed further.

Key words: Diabetes, gestational, Hemoglobin A, glycosylated, Glucose tolerance test, Diabetes mellitus, Forecasting