Hepatitis B-Virus (HBV) is a 40-42-nm enveloped virus classified in the Hepadnaviridae family, which infects the liver [1]. HBV contains a circular, partially double-stranded DNA genome that is 3.2 kb in length [2]. It is primarily infects hepatocytes and may lead to chronic hepatitis, liver cirrhosis, hepatocellular carcinoma (HCC), and other severe liver diseases [3, 4]. HBV is commonly transmitted from an infected person to others through direct contact with infected blood, unprotected sexual intercourse, from an infected woman to her newborn during pregnancy and childbirth, use of Needles and other medical/dental equipment or procedures that are contaminated or not sterile [5, 6]. The other potential routes of this infection are body piercing, tattooing, acupuncture, and even nail salons unless sterile needles and equipment are used [7].

Most vertical transmission of hepatitis B virus from mother to child are at the time of labor. Infants born to mothers who are positive for both HBsAg and hepatitis B e antigen (HBeAg) are at a higher risk of acquiring infection (transmission risk for HBsAg positive and HBeAg-positive mothers: 70-100% in Asia and 40% in Africa) than those born to HBsAg-positive mothers who have lost the HBeAg (5-30% in Asia and 5% in Africa) [8-10].

Diagnosis of HBV is made by detecting its sero markers and biomarkers, which include HBsAg, antibody to hepatitis B surface antigen (anti-HBs), HBeAg, and antibody to hepatitis B core antigen (anti-HBc), and nucleic acid-based tests, and histological techniques [7]. Acute HBV infection is characterized by the presence of HBsAg and immunoglobulin M (IgM) antibodies to the core antigen, HBcAg. During the initial phase of infection, patients are also seropositive for hepatitis B envelop antigen (HBeAg) [6]. HBeAg is usually a marker of high ranges of replication of the virus. The presence of HBeAg indicates that the blood and body fluids of the infected person are enormously infectious [11]. Tenofovir, or entecavir- is the most potent oral drug recommended by WHO and used to suppress the hepatitis B virus. Their resistance rate is low compared to other drugs that are easy to take (1 pill per day) and have few side effects. Therefore, only limited monitoring is required [12].

HBV transmission can be prevented through screening of all pregnant women for HBsAg and providing antiretroviral therapy, HepB vaccination for infants, giving HBV vaccine with HBIG for children born from infected mothers, screening blood before donation, routine vaccination of previously unvaccinated children aged <19 years, vaccination of adults at risk for HBV infection, including those requesting protection from HBV without acknowledgment of a specific risk factor and education programs directed towards disease awareness [13].

Globally, in 2015, an estimated 257 million people lived with chronic HBV infection, and 4.5 million new cases of HBV were reported per year. In 2015, 1.34 million deaths occured due to the hepatitis B virus. Moreover, 720,000 and 470,000 individuals died due to cirrhosis hepatocellular carcinoma [14].

The magnitude of chronic HBV infection varies widely according to the geographical area and principal routes of transmission. The global prevalence of chronic HBV infection varies widely, Africa and Asia from high (≥8%,), Southern and Eastern Europe to intermediate (2-7%)) and Western Europe, North America, and Australia low (<2%,), and a medium to high endemicity of HBV was reported in Ethiopia [15].

The main route of transmission of HBV infection in many parts of the globe is perinatal. The threat risk of vertical transmission depends on the time at which a pregnant woman acquires HBV infection. In the absence of immuno-prophylaxis, 10-20% of women seropositive for HBsAg transmit the virus to their neonates [16]. Perinatal infection which counts for up to 90% of developing the risk of chronic infection. Whereas between the age of 6 months to 5 years, the risk of chronic infection decreases to 20-60% [17].

The main complication of viral hepatitis during pregnancy is spontaneous abortion, IUGR, premature delivery and low birth weight of infants [18, 19].

Different studies conducted in Ethiopia shows that the occurrence of HBV infection in pregnant women ranged from 3.0% to 8.1% [10, 20-22]. These indicate that pregnant women in different geographical areas have a different prevalence of HBV infection. Very little was recognized about the prevalence, infectivity, and associated factors of Hepatitis B virus infection among pregnant women in the study area. Therefore, this study aimed to determine the Seroprevalence, infectivity, and related factors of HBV infection among pregnant women attending antenatal clinics at Sankura Primary Hospital, Southern Ethiopia.

Early screening of pregnant women for HBsAg is one of the most important tasks to design an effective intervention and control program. Hence, the present study was aimed to assess the prevalence of HBV infection, infectivity, and associated factors among pregnant women attending the ANC clinic of Sankura Primary Hospital, Southern Ethiopia [25]. The seroprevalence of HBsAg in the current study was 11 (3.3%) (95% CI 1.5% - 5.0%). According to theclassification of the WHO, the seroprevalence of HBsAg among pregnant women in this study could be classified as moderate endemicity (2-7%) [26].

The seroprevalence rate of HBsAg in this study was in agreement with the studies conducted in different parts of Ethiopia; 4.4% in Felegehiwot referral hospital, Northwest Ethiopia [22], 3.5% in Dawro zone, south Ethiopia [24],2.4% in East Welega [27], 2.3% in a rural hospital of south Ethiopia [28], 4.5% Atat Hospital, South Ethiopia [29], and 3% in selected health facilities, Addis Ababa, Ethiopia [30]. Similarly, the current result was also consistent with studies that reported 3% in a tertiary hospital in Mwanza, Tanzania [31], 2.1% in Turkey [32], and 2.26% in Bulgaria [33]. This highlights that pregnant women in Ethiopia and other countries may have a similar risk of exposure to and/or rate of HBsAg clearance.

In contrast, our finding was lower than results reported from other parts of Ethiopia; 5.3% in central Ethiopia [34], 7.8% in southern Ethiopia [35], 6.1% in West Hararghe public hospitals,Oromia region, Ethiopia [36] and 7.9% in Gambella, south-west Ethiopia [37]. Moreover, the present result was found to be lower than the figures reported; 10.2% in Cameroon [38] and 12.3% in the Gambia [39]. This lower prevalence might be due to differences in the prevalence of HBV in the general population, sample size, local risk factors, and methods used for testing HBV. On the other hand, the prevalence of HBsAg in this study was higher than the prevalence rates of 0.9% reported in brazil [40] and 0.9% in India [41]. The difference in seroprevalence of HBV infection might be attributed to the difference in screening and vaccination coverage for HBV.

Perinatal transmission of HBV is strongly associated with HBeAg- positivity in childbearing women and implies the highest risk for developing chronic HBV infection with 85% to over 90% of babies born to HBeAg positive mothers becoming chronic HBV carriers [35]. However, only 18.2% were positive for HBeAg out of all HBsAg positive pregnant women. This finding was higher compared to studies conducted in Addis Ababa, Ethiopia 12.5% [30] Cameroon 12.1% [38], and Tanzania 9% [31]. In contrast, lower results were reported compared to findings reported by Yirgalem hospital, South Ethiopia, 38.8% [42]. Conflicting results were reported regarding the infectivity of HBV in African countries, therefore, further investigation is needed to resolve this issue.

In this study, sociodemographic variables like age, marital and educational status, residence, and occupation of participants as well as reproductive variables like gestational age and gravidity, were not significantly associated with the risk of HBV infection. This finding concurred with the study conducted in Felege Hiwot Referral Hospital, Ethiopia [22] and Atat Hospital, Southern Ethiopia [29]. However, in contrast, some studies showed that pregnant women with no formal education had higher odds of HBV infection [21].

In the current study, pregnant women who had a history of blood transfusions were almost five times more likely to have the risk of acquiring HBV infection compared to those who had no blood transfusion history. This result is in line with the findings in Atat Hospital, Southern Ethiopia [29], Felegehiwot referral hospital, Northwest Ethiopia [19], and Nigeria [38]. This may be explained because of the hepatitis B virus is transmitted through any fluid, mucosal blood contact from infected patients easily.

Pregnant women who had contact with a family history of liver disease were more than 4 times more likely to be infected with HBV than women who had no contact with a family history of liver disease, which is consistent with a study conducted in Cameroon [38]. This can be explained by the fact that HBV can be transmitted by contact with fluids secreted from an infected individual.

Factors significantly associated with HBV infection in other studies were not found in this study. The lack of significance for other characteristics may be due to the small number of HBsAg positive cases that could conceal significant results in the logistic regression. Therefore, additional studies with larger sample sizes are necessary to confirm these results.

Our study has some limitations. First, we used rapid diagnostic tests, which are less sensitive than ELISA or PCR tests, leading to a possible underestimation of the prevalence of assessed markers. Second, we determined the HBV infectivity based on HBeAg only, and we did not look for anti-HBe antibodies and HBV viral load, which are also important determinants of HBV transmission. Despite these shortcomings, this study gives important information about HBV infection in pregnant women in a setting of very limited epidemiological data.

The prevalence of HBV infection among pregnant women is intermediate. The rate of HBV infectivity was 18.2% of HBsAg-positive women having evidence of HBeAg in their plasma. A higher risk of HBV infection was observed among pregnant women who had a history of contact with a family history of liver disease and who had a blood transfusion. The relatively low prevalence of women positive to both HBsAg and HBeAg in the study population suggests that perinatal transmission of HBV might not be the major mode of HBV transmission in this area. Further studies are needed to assess thoroughly the burden and determinants of MTCT of HBV in this setting. Therefore, the Ministry of Health, local government, and other concerned organizations should take note to increase the screening of pregnant women and vaccination of HBV.