Anti-retroviral therapy has led to a significant reduction in morbidity and mortality related to HIV/AIDS. However, this cannot be fully realized without addressing the barriers related to retention in care and medication adherence.A cross-sectional study design was implemented to select 293 pregnant women on option B+ anti-retroviral treatment (ART). The collected data was cleaned and entered into Epidata version 3.1 and exported to SPSS Version 21 for analysis. Multiple logistic regression models were used to indicate the association between variables.The overall drug adherence of pregnant women on ART medications was 82.6%. The study showed that participants educational status, AOR 4.54(95% CI; 1.72-11.95), participants status disclosure 2.61(95% CI; 1.01-6.71), social and financial support to the participants AOR 2.76(95% CI; 1.17-6.51), counseling on the benefit AOR 2.9(95% CI; 1.27-6.63), were all positive and significantly associated with adherence to option B + treatment, while experience of drug side effect AOR 0.24(95% CI; 0.1-0.6), and fear of stigma and discrimination AOR 15.79(95% CI; 4.64-53.67), were negatively associated with adherence to option B+ treatment.Educational status, counseling on the health benefit of treatment for the fetus and the mothers, social and financial support favors adherence while fear of stigma and discrimination and drug side effects negatively affect adherence to option B+. The study calls for collaborative work among patients, healthcare professionals, and the public to enhance ART adherence.