Human immunodeficiency virus (HIV) and Hepatitis B virus (HBV) infections are the two most important infectious diseases throughout the world particularly in developing countries. Both HIV and HBV share common ways of transmission in humans, which accounts for the high frequency of HIV-HBV co-infections. HIV and HBV have common risk factors like injectable drug use and blood transfusion [1]. In Ethiopia, the overall of prevalence of HIV among pregnant women attending anti-natal care (ANC) was 5.3%. Moreover, the prevalence was higher in pregnant women from urban (9.5%) than rural areas (2.2%) [2].

Hepatitis B virus causes both acute and chronic hepatitis. The global prevalence of chronic HBV infection is clustered as high (≥8%), intermediate (2-7%) and low (<2%). Thus, Ethiopia belongs to the high prevalence category [3]. Chronic active hepatitis B virus infection results in cirrhosis and hepatocellular carcinoma [4, 5]. The probability of becoming a chronic HBV carrier is inversely related to age at the time of infection. Neonatal HBV infection always leads to a chronic carrier state [6, 7]. Chronic HBV infection at birth occurs in approximately 90% of infants born from mothers who are positive for hepatitis B surface antigen (HBsAg) and hepatitis B e-antigen (HBeAg) [8]. In addition, maternal transmission of HBV predisposes infected newborns to liver cirrhosis and hepatocellular carcinoma in young adulthood [9]. HBV infection in infancy usually leads to a chronic carrier and then leads to liver cirrhosis and hepatocellular carcinoma. Therefore, the prevention of vertical transmission of HBV is very important, [10].

Co-infection rate of hepatitis B virus and HIV is common which leads to increased morbidity and mortality as compared to HIV or HBV mono-infections [11, 12]. The prevalence of HIV-HBV co-infection is reported as high as 10-20% in countries where HBV infection is either endemic or intermediate to high [11]. Moreover, in countries where the viruses are highly endemic, the rate can be as high as 20-25% [11, 13]. Both HIV and HBV are transmitted via sexual intercourse and mothers to offsprings. Thus, the prevalence of HIV and HBV infection in pregnant women can represent the majorities of the population in the communities because pregnant women are the interface for their sexual partners and infants.

Studies in Ethiopia have indicated that HBV and HIV are endemic with regional variation [14–16]. However, there is a scarcity of information on the prevalence of HBV and HIV infection among pregnant women in the study area. The present study was conducted to assess the sero-prevalence of HBV and HIV infection among pregnant women and to identify risk factors associated with HBV and HIV infection in Bahir Dar city.

In the present study, the overall prevalence of HIV infection among pregnant women was higher (6.6%) than the national HIV prevalence among pregnant women (5.3%) [2]. Likewise, HIV prevalence was higher than the study conducted in Southern Ethiopia (1.8%) [17] and Mali, (0.4%) [18]. In contrast, it is lower than reports from Gondar in Ethiopia [14] and in Nigeria (8.4%) [19]. The majority of HIV positive participants in this study were among the age group 21–24 years old. Similarly, 13% of HIV prevalence was reported in the same age group (21–24 years) in Gondar, Ethiopia [14]. This age group is the most vulnerable group for HIV infection.

According to the WHO classification, the prevalence of HBV among pregnant women in this study was intermediate (2-7%) [3]. The prevalence of HBV infection in the present study conforms with reports from the study in Nigeria (3.8%) [19] and Jimma, Ethiopia (3.7%) [15]. However, the prevalence of HBV in the current study was higher than the study conducted in India (0.9%) [20] and Tripoli, Libya (1.5%) [21]. In contrast, it was lower than the study documented in Taiwan (15.5%) [22], Keffi in Nigeria (6.67%) [23] and Gondar in Ethiopia (7.3%) [14]. These differences might be attributable to cultural and behavioral differences for the risk factors of HBV infection.

The frequency of HBV and HIV co-infection (19.0%) in this study was higher than the study done in Southern Ethiopia (0.6%) [17] and Nigeria (9.5%) [19]. Furthermore, the prevalence of HIV infection among HBsAg positive pregnant women was 33.3%. Most of the time comorbidity of HBV and HIV infection is common among risk groups. Because, both HBV and HIV share common mode of transmission.

Regarding socio-demographic status of the study participants, the highest proportion of HBV infection was among pregnant women who were not literate and those whose average monthly income was less than one thousand Ethiopian Birr. Likewise, similar finding was also reported from Jimma in Ethiopia [15]. The highest prevalence of HBsAg was detected in pregnant women who were on a secondary trimester. This was also in line with the study conducted in Minna, Nigeria [24].

In this study all of the socio-demographic variables were not statistically significant. However, pregnant women who had a previous history of blood transfusion were about 3.7 times more likely to be positive for HBsAg (AOR = 3.70, CI, 9.02-14.84). A similar study, which was conducted in Egypt identified this variable as significant associated factor [25]. Study participants who have body tattooing on any part of their body was also 5.7 times more likely to be HBsAg positive (AOR = 5.74 CI, 1.24-26.50). Studies conducted from Bamako, Mali and Addis Ababa, Ethiopia identified that body tattooing has a significant association with HBV infection [16, 26]. Moreover, surgical application was one of the risk factor which was statistically significant, (AOR = 11.1 CI, 2.64-46.88) [25].

Unsafe injection like traditional healers’ practice is one of the risk factors for HBV transmission. In our study, pregnant women who had a history of unsafe injection were 5.6 times more likely to be HBV positive (AOR = 5.6 CI, 1.44-22.19). Previous studies showed that patients who received more injections and injected with non-sterile needle were more likely to be infected with hepatitis virus [27]. This practice is also common in our country where different cultural application on unsafe injection is practiced. Among explanatory variables, previous history of piercing with sharp materials (AOR = 3.0, 95% CI 1.17-7.80) and history of abortion (AOR = 6.6, 95% CI 2.50-17.71) were significantly associated with HIV infection.

Detection of other markers of HBV like HBeAg and DNA was not possible because of lack of laboratory setup. Moreover, HIV/RNA viral load was not determined for HIV positive pregnant women. These can be considered as the major limitation of this study.

This study showed that HIV and HBV infections are important public health issues in our region that need to be addressed. All pregnant women need to be screened for both HIV and HBV infection during antenatal care. Blood transfusion, body tattooing, surgery and unsafe injection were risk factors for HBV infection. Moreover, previous history of piercing with sharp materials and history of abortion were major risk factors for HIV infection. Thus, health education about these risk factors in particular and the mode of transmissions and prevention of HIV and HBV in general should be given.