BACKGROUND: Most African countries, including Ethiopia, have not developed local well-defined reference intervals (RIs) for immuno-hematological testes in terms of pregnant women. As a result, we were using reference intervals derived from non-Africans. This is not appropriate because CD4 + T cell counts (CD4 count) are affected by several factors including ethnic and environmental factors. Therefore, this study aimed to develop reference interval for CD4 count for apparently healthy pregnant women in Addis Ababa, Ethiopia. RESULTS: After excluding six pregnant women who did not pass the screening tests, 156 apparently healthy pregnant women who were 18-49 years old were included in the final analysis. The medians of CD4 absolute counts and CD4% with inter-quartile ranges [IQR] were 757.5 [611.3-925.5] cells/µL and 43.6% [39.9-47.3] respectively while the median and IQR hemoglobin values were 14.3 g/dL [13.4-15.1]. The respective reference intervals for absolute CD4 cell count and % CD4 were 416.9-1218.4 cells/µL and 32.1-57.3%, respectively. Significant changes were observed in hemoglobin level between trimesters (P <
0.05). CONCLUSION: The results of this study showed a decrease in both percentage and absolute CD4 + T cell counts when compared to those of non-African and African countries. Establishing local reference values for diverse groups is therefore crucial.