Objective  To explore the relationship between red blood cell parameters in early pregnancy and gestational diabetes mellitus (GDM), and to provide evidences for early screening of GDM.

  Methods  A hospital-based retrospective cohort study was conducted among 25 044 singleton pregnant women hospitalized in a maternal and child health care hospital in Beijing during the period from January 2013 through December 2017. From the hospital′s electronic information system, we extracted the data on the pregnant women's red blood cell count (RBC), hemoglobin (Hb), and hematocrit (HCT) detected in their first trimester and other relevant information. Then we assigned the pregnant women into four groups according to the quartile values of red blood cell parameters and the GDM of the women in different groups were compared. Multivariate logistic regression analysis was adopted to assess the associations of the red blood cell parameters with the incidence of GDM.

  Results  The incidence of GDM was 23.32% (5 840/25 044) in the pregnant women. With the increment of Hb, RBC, and HCT quartile values in early pregnancy, the incidence of GDM increased gradually (P < 0.001 for all). Multivariate logistic regression analysis revealed that the Hb, RBC, and HCT value were independent risk factors of GDM after adjusting for age, education, history of macrosomia, family history of diabetes, first pregnancy, primipara, and pre-pregnancy body mass index (BMI). The pregnant women with higher values of the red blood parameters (≥ 75% quartile) were at significantly increased risk of GDM compared to those with lower values (< 25% quartile), with the odds ratio (95% confidence interval) of 1.61 (1.46 – 1.77) for Hb, 1.62 (1.47 – 1.78) for RBC, and 1.46 (1.33 – 1.61) for HCT, respectively.

  Conclusion  The levels of Hb, RBC and HCT in early pregnancy are independent risk factors for GDM and these parameters are of potential application to the early screening of pregnant women at higher GDM risk.