Aims: Blood Group Antigens (ABO) are present on the surface of all cells, including urinary tract cells. Besides, they are a predisposing factor for infection in various parts of the body. The present study aimed to determine the prevalence of bacteriuria and its relationship with different blood groups. Methods & Materials: This descriptive-analytical (cross-sectional) study was performed in 2019 on 400 pregnant women who were selected by convenience sampling method. For each pregnant woman referring to Allameh Behlool Hospital in Gonabad City, Iran, a form including patients’ demographic characteristics, medical history, and blood type was completed. Data analysis was performed in SPSS using descriptive statistics and the Chi-squared test. The significance level of the tests was considered P<0.05. Findings: Of the explored 400 pregnant women with a Mean±SD age of 27.31±5.9 years, 58 were bacterially positive. There was a significant relationship between bacteriuria and ABO blood groups (P=0.001). The examined pregnant women with blood groups O (48.3) and B (29.3) were at higher risk of bacteriuria. There was a significant relationship between bacteriuria and gestational age (P=0.016); accordingly, 56.9% of the study subjects with bacteriuria were in the third trimester. There was no significant relationship between bacteriuria and educational level (P=0.944), and place of residence (P=0.494). Conclusion: The prevalence of bacteriuria among referred pregnant women was measured to be 14.5%. Moreover, pregnant women in the third trimester of pregnancy with blood types O and B were at higher risks for bacteriuria. Therefore, considerations, such as advising this group about the susceptibility to bacteriuria and urinary tract infections, personal hygiene, and faster referral for diagnostic and therapeutic measures if presenting symptoms, as well as informing doctors and obstetricians about this condition and help to make faster decisions are recommended in this respect.