Background: In recent times, the role of ABO and Rhesus grouping in clinical practice has increased widely. There is a paucity of literature on blood group distribution, and its distribution has not been studied in our centre. This study aimed to determine the distribution of ABO, Rh D blood groups and haemoglobin genotype among pregnant women initiating antenatal care in Rivers State University Teaching Hospital (RSUTH). Methods: This was a cross-sectional study among antenatal clinic attendees in RSUTH, over 6 months. At booking 3ml of venous blood was collected in Ethylenediaminetetraacetic acid (EDTA) vacutainer from the pregnant women, and ABO and Rh D typing was done by tile methods forward and reverse grouping methods and confirmed by microscopy. Haemoglobin genotype was done by electrophoresis. Data collected were analyzed using IBM Statistical Product and Service Solution (SPSS), version 25.0 (Armonk, New York). Results: One thousand one hundred and forty -seven patients were recruited for the study. Their mean age and mean gestational age at booking were 31.6 SD 4.6 years (95% CI: 31.3,31.8), and 21.1 SD 18.6 weeks respectively. Modal parity was para 1. The predominant blood group among pregnant women at the RSUTH was O [667 (58.2%)], followed by A [286 (24.9%)], B [171(14.9%)], and AB [23(2%)]. The prevalences of Rhesus D positive and Rhesus D negative blood group were 95.2% and 4.8% respectively. Concerning genotype, the most predominant was AA 898 (78%) followed by AS [245 (21.4)], SS [4 (0.4%)], and AC [2 (0.2%]. Conclusion: The predominant blood group and genotype among pregnant women in our centre is O Rh D positive and AA respectively. The findings from this study would help plan transfusion services antepartum and post-partum. This will be relevant in transfusion and coagulation management of obstetric haemorrhage.