Aims: The study was carried out to determine the prevalence of anaemia among pregnant women attending St. Mary's Hospital Okpoga, Benue State, Nigeria, with respect to demographic factors, socio-economic and underlying medical determinants among pregnant women. Methodology: A retrospective study design was used for the study. The study of 858 pregnant women who booked for antenatal care (ANC) between March 2019 to March 2020 was done. Their records were retrieved from the Records Department and the ANC unit using a standard proforma. Results: The findings revealed that prevalence of anaemia among pregnant women at booking was (55.2%). The highest prevalence of anaemia by age range 15-20 years was (62.2%), by educational status, highest prevalence was among those with no formal education (84.3%), by occupation highest prevalence was among house wives (59.9%). By underlying medical condition – severe form of parasitaemia (78.5%), by degree of severity, mild form of anaemia 74.1%, was most prevalent. By parity, it was highest among multiparous women (66.9%), by habitants it was highest among rural habitants (73.9%) while prevalence by gestational age it was highest among pregnant mothers who were in their 3rd trimester (60%) in the first antenatal care (ANC) visit. Conclusion: Pregnant mothers need to book early for antenatal clinic to access services such as intermittent preventive treatment, uptake of iron supplements and anthelmintics. They should also be empowered economically to access ANC in order to reduce the problem of anaemia in pregnancy.