Objectives: To determine the prevalence of gestational diabetes mellitus (GDM) among pregnant women with varied hemoglobin concentrations (HC). 
Patients & Methods: 847 newly pregnant women underwent estimation of HC, evaluation of insulin resistance (IR) using the homeostasis model assessment of IR (HOMA-IR) score and glucose tolerance using 75-oral glucose tolerance test (OGTT) at the 6th, 13th, 24th, and 36th gestational week (GW). Women were categorized according to the 6th GW HC into Low (<11 g/dl), Normal (11-<13 g/dl), and High HC (>13 g/dl). Women who had LHC received iron supplemental therapy (IST) till HC was adjusted, and IST was stopped. The study outcome is the incidence of IR and/or GDM among the studied women, and the predictability of the 6th GW HC for the oncoming development of IR and/or GDM.  
Results: This is a cross-sectional study conducted at a University Hospital in the time period from January 2017 to June 2018, with the aim to evaluate cases presenting with a confirmed diagnosis of perforated IUCD.  
Results: At the 6th GW the frequency of LHC, NHC, and HHC was 22%, 64%, and 14%, respectively. During pregnancy, the frequency of NHC women decreased, while that of HHC women increased. The frequency IR and HOMA-IR score progressively increased during pregnancy in all women with significantly higher frequency and score among HHC women. At the 24th and the 36th GW, 75 and 71 women developed GDM with significantly higher frequency among HHC women than LHC and NHC women and in LHC women compared to NHC women. Statistical analyses defined high HC at the 6th GW as the significant predictor for the development of GDM at the 24th GW, while high BMI at the 6th GW and multiparity as predictors for high HOMA-IR score. 
Conclusion: Preconception evaluation of HC is mandatory to define women with low or high HC. Women who had low HC must be managed cautiously using IST till having NHC and IST must be stopped. HHC early in pregnancy could predict the oncoming development of IR and GDM.