Total and Differential White Blood Cell Counts among Women Using Oral Contraceptives in Owerri, Southeastern Nigeria: A Comparative Cross-sectional Study

Abstract

Background: Oral contraceptives are widely used for family planning, yet their relationship with                circulating leukocyte patterns is not fully understood and may differ according to population and hormonal formulation. Objective: To compare total and differential white blood cell counts in women using oral contraceptives with those of healthy non-users in Owerri, Imo State, Nigeria. Methods: This comparative cross-sectional study involved 100 women aged 18-45 years, comprising 50 regular oral-contraceptive users and 50 non-users. Five millilitres of venous blood were collected into ethylenediaminetetraacetic acid containers. Total white blood cell count was measured using an automated haematology analyser, while differential leukocyte percentages were determined from Leishman-stained blood films after 100 leukocytes had been classified. Data were analysed using descriptive statistics, the independent-samples t-test and Pearson correlation. Statistical significance was set at p<0.05. Results: Mean total white blood cell count was lower among users than controls (4.89 +/- 1.61 vs. 7.60 +/- 1.22 x 10^9/L; p<0.0001). Users had a higher neutrophil percentage (55.80 +/- 8.13% vs. 35.62 +/- 9.32%; p<0.0001), but lower lymphocyte (35.66 +/- 8.76% vs. 55.26 +/- 9.57%; p<0.0001) and monocyte percentages (5.18 +/- 1.61% vs. 7.28 +/- 2.68%; p<0.0001). Eosinophil and basophil percentages were also higher among users (p=0.0381 and p<0.0002, respectively). Age was not significantly correlated with any measured leukocyte parameter among users. Conclusion: Oral-contraceptive use was associated with a lower total white blood cell count and a different relative distribution of leukocytes in this study population. The cross-sectional design and use of percentage differentials, however, do not permit causal or functional interpretation. Larger longitudinal studies that account for contraceptive formulation, duration of use, absolute differential counts and relevant confounders are needed.