Prevalence and associated factors of hepatitis B virus infection among pregnant women attending antenatal care at Agena health center, South Ethiopia, 2019: a cross sectional study

Background; Hepatitis B virus (HBV) is the world’s most common and highly contagious liver infection. Its transmission methods are: mother to child, via open wounds, sexual contact, blood transfusion and other blood contact related activities. Prevalence of HBV among pregnant women in Africa ranges from 3.67 - 16.5% and in Ethiopia 2.4 to 8.4%. Hepatitis B infection leads to high morbidity and mortality for mother as well as for their infants due to the vertical transmission. Hence assessing the prevalence and associated factors of Hepatitis B Virus infection is a priority. Methodology : An institution based cross sectional study was conducted with a total of 194 of pregnant women attending antenatal care at Agena health center from May 1-30/2019. Frequency analysis and Logistic regression test was used to determine the associated factors associated with Hepatitis B virus by using SPSS version 25. Results: The prevalence of HBV in Agena health center among pregnant women were 4.1% and it was associated with marital status, history of hospital admission and history of abortion. Conclusion : The prevalence of HBV in Agena health center among pregnant women was intermediate. Since routine screening and immunization of all pregnant women is mandatory.

Even if HBV is the most common and highly contagious diseases for the whole population, it is highly prevalent among pregnant women (general population 9.41% versus pregnant women11.11%) and it has different maternal complications and fetal death due to vertical transmission [4]. There is a high chance of vertical transmission from HBV infected mothers to their infants during delivery and during breast feeding [5,6]. A Study in Addis Ababa shows that based on the infants cord blood samples, 75% infants were infected with HBV who were born from the infected mothers [7]. To prevent the vertical transmission of HBV, vaccination and Antiviral therapy for the infected pregnant women is very crucial [8].
Hepatitis B vaccination should be also given for the infants who are infected with HBV [9].
HBsAg prevalence among pregnant women was 3.1% in Shenyang, China. Only 23.4% and 17.7% of pregnant women knew their HBV status before gestation and before delivery respectively [10].The prevalence of HBV infections among pregnant women in Africa was 6.8% and child vaccination, routine and universal antenatal hepatitis B virus screening program is very important [11]. The prevalence of HBV infections among pregnant women was 16.5% and 9.2% in Osogbo, Nigeria and Gambia respectively [12,13]. Studies show that the prevalence was low among pregnant women who were vaccinated for HBV infection but high prevalence was seen among pregnant women who did not vaccinated for HBV infection [12,13].
In Ethiopia the prevalence of hepatitis B virus infection among pregnant women was intermediate (4.7%), with the prevalence of HBSAg positivity ranging from 2.3% to 7.8% [14]. Different studies in Ethiopia shows those pregnant women who have history of multiple sexual partners, history of abortion, and history of surgical procedures, body tattooing and ear/nose piercing have a high chance of infected with HBV [15][16][17][18][19].
Prevention of HBV infection among pregnant women is very important to prevent the 4 transmission of HBV infection from mother-to-child. An effective strategy for reducing the incidence of the infection is identifying and handling the associated factors as well as giving awareness for the pregnant women. However, limited information has been published regarding the prevalence of HBV among pregnant women in Ethiopia as well as in Gurage zone and there is no evidence based interventions. Therefore, the aim of this study was to assess the sero-prevalence and risk factors of HBV status among pregnant women receiving care at Agena health center ante-natal care (ANC) clinic.

Study design and area
Institutional based cross-sectional study design was conducted in Agena town, Ezha woreda at Agena health center, Gurage zone Ethiopia from May 1-30, 2019. Agena is the only urban kebele found in Ezha woreda, Gurage zone, South Ethiopia. Agena is located to the Southwest 198 km from Addis Ababa, 38 km from wolkite and 23.17 km from Wolkite University.

Source population
The source populations were all pregnant mothers who were attending ANC in Agena Healt Center.

Study populations
The study populations were pregnant mothers who were attending ANC follow-up and fulfill the inclusion criteria in Agena health center from May 1-30, 2019.

Exclusion criteria and inclusion criteria
The pregnant women who have at least one ANC visit at Agena health center were included in the study. The pregnant women whose HBV status is unknown, who is already in labour, which is seriously ill or admitted in the ICU ward was excluded from the study.

Sampling size determination
The sample size was determined by using a single population proportion formula by considering the following assumptions: standard normal distribution with confidence interval (CI) of 95% (Za/2=1.96), absolute precision or tolerable margin of error (d=0.05), and the prevalence of HBV infection among pregnant women Attending Antenatal Care in Public Health Facilities, Dire Dawa in 2018 was 8.4% [20]. Assuming a 10 % non-response rate the total sample size of 194 pregnant women were selected from Agena Health Center. A study participant was selected by using systematic random sampling method from the appointment log of May, 2019.

Data collection tool and method
Data was collected by face-to-face interview using structured and pre-tested questionnaire which is adapted from relevant literatures and modified to local context in such a way that all the variables to be assessed were included and HBV status was taken from routine ANC document for each participants. The tool was first prepared in English and translated to Amharic then to the local Guragegna language then back to English again to check for its consistency.

Data processing and analysis
Data was checked for its completeness and cleaned before it was entered to a computer.
Then it was coded and entered into EpiData version 4.2.0.0 and importing to SPSS version 25 software packages for data analysis. Frequencies and proportions were used to describe the study participants. The data was presented by using tables and graphs.
Bivariate analysis and crude odds ratio with 95% confidence interval (CI) was used to see the association between independent variable and the outcome variable by using binary logistic regression. Independent variables with p-value of =0.25 were included in the multivariate analysis to control confounding factors. Adjusted odds ratio along with 95% CI was estimated to identify the factor associated with HBV infection among pregnant women 6 using multivariable logistic regression analysis. Level of statistical significance was declared at P-value = 0.05.

Ethical clearance
The ethical clearance was approved and obtained from Wolkite University Institution Research Board. Letter was submitted to Gurage zone health office and Agena Health Center then permission was obtained from those bodies. Prior to interview; all participants recruited to the study were received written informed consent about the study. The participants did not gain any incentives and direct benefit, yet the result can be used as a baseline for further studies. The study has no any risk for the participants and their confidentiality was kept.  (Table 1).

Hospital associated factors for HBV infection
Among the total population of the respondents 27(13.9%) had at least one history of hospital admission, 25(12.8%) had history of dental procedure in hospital, 20(10.3%) of them had surgical procedure and blood transfusion or donation each in their previous history.

Factors associated with HBV infection among pregnant women
Those variables with a P-value of ≤ 0.25 in the Binary logistic analysis were entered to multivariable logistic analysis to identify the independent factors associated with hepatitis B virus among pregnant women.
In bivariate analysis the independent variables: marital status, history of hospitalization, blood transfusion or donation, abortion, circumcision, alcohol drinking, chat chewing, were associated with hepatitis B virus among pregnant women. In multiple logistic regression analysis, the independent variables: marital status, history of hospital admission, and abortion were statistically significant at 5% level and were found to be the associated factors of hepatitis B virus infection among pregnant women (Table 4).
Generally being single exposes for HBV infection because single women might have multiple sexual partners. But in those studies there might be an increased prevalence as a result of married women might be more diagnosed than single during ANC follow up and during the delivery procedure.
Those pregnant women with history of hospitalization were 97% times more likely to be reactive to HBV infection than the pregnant women who had no history of hospitalization [AOR=0.030(0.002-0.377)]. This finding was consistent with the study conducted at Arba Minch Hospital [18].This might be occurred due to that hospitalized women might easily acquire the infection during different procedures than the pregnant women who had no history of hospitalization .
Those pregnant women who had history of abortion were 10 times more likely to be reactive to HBV infection than the pregnant women who had no history of abortion [AOR= 10.331(1.161-92.926)]. This finding was consistent with the studies conducted at Dawuro zone, Southwest Ethiopia, at Deder Hospital, Eastern Ethiopia and Bahir Dar city, Northwest Ethiopia [16,17,19]. It might be occurred due to the abortion might be unsafe so it expose for HBV infection. However, no significant association between previous history of abortion and HBsAg positivity was observed at the studies conducted at Yirgalem Hospital, Arba Minch Hospital, and Hawassa university referral hospital [15,18,23]. This may be due to the implementation of policies aimed at reducing the incidence of unsafe abortions and health education related to unsafe abortions.  Authors' contributions HW conceived the study and developed the study design, analysis, report writing and drafted the manuscript. MN, IT and AA were involved in data entry, data analysis, report writing and manuscript preparation. All authors read and approved the final manuscript.

Acknowledgment
Firstly we would like to acknowledge the study participants for their participation.
Finally, our grateful appreciation extends for Wolkite University for providing fund to conduct this study and for Gurage Zone Health office and Agena Health center staffs for their support during the study.  18 P<0.05**, P<0.01***, COR=crude odd ratio, AOR=adjusted odd ratio, reference=1.00