Factors associated with hepatitis B virus infection among pregnant women attending antenatal clinic in Western Area Urban District, Sierra Leone

Abstract

Background:

Hepatitis B virus infection remains a global health concern, particularly in resource-constrained countries such as Sierra Leone. Understanding the risk factors for hepatitis B virus among pregnant women can guide public health initiatives, prenatal care, and maternal–child health policies.

Objectives:

We assessed the prevalence and risk factors for hepatitis B virus infection among pregnant women in Sierra Leone’s Western Area Urban District.

Design:

We conducted a facility-based cross-sectional study in five randomly selected hospitals in the Western Area Urban District.

Methods:

A cross-sectional study was conducted in five randomly selected hospitals in May 2021. Data were collected from 320 pregnant women using structured questionnaires. Hepatitis B virus infection, identified by hepatitis B surface antigen positivity, was analyzed using descriptive statistics, Pearson’s chi-square test, and logistic regression. Variables that were significant in bivariate analysis were included in the multivariable model. All tests were computed with 95% confidence intervals.

Results:

The mean age of participants was 26.0 ± 5.7 years, and the prevalence of hepatitis B virus infection was 13.8% (95% confidence interval: 10.4–18.0). Women with no formal education (adjusted odds ratio: 3.69, 95% confidence interval: 1.33–10.22) or primary education (adjusted odds ratio: 8.30, 95% confidence interval: 2.69–25.63) had significantly higher odds of infection. Single women (adjusted odds ratio: 3.05, 95% confidence interval: 1.29–7.22) and those engaging in risky practices, such as toothbrush sharing (adjusted odds ratio: 1.37) or tattooing (adjusted odds ratio: 2.09), were more likely to be infected. Conversely, a history of stillbirth (adjusted odds ratio: 0.20, 95% confidence interval: 0.04–0.99) was associated with reduced odds of infection.

Conclusion:

Hepatitis B virus infection was common among pregnant women in Sierra Leone’s Western Area Urban District. Education level, marital status, and unsafe practices such as tattooing and toothbrush sharing were significantly associated with hepatitis B virus infection risk. The findings emphasize the urgent need for targeted public health interventions to reduce hepatitis B virus transmission in this population.

Introduction

Hepatitis B virus (HBV) poses a significant global public health concern, particularly affecting pregnant women who can transmit the virus to their offspring at birth. The virus spreads through infected blood, bodily fluids, unprotected intercourse, and needle sharing. ¹ Worldwide, ~296 million individuals are affected by HBV, leading to around 820,000 annual deaths due to complications such as liver cancer and cirrhosis. ² Chronic hepatitis B is a major cause of liver cancer, especially in low- and middle-income countries where infectious diseases are prevalent.^3,4

Africa, alone, bears a substantial burden, with an estimated 65 million individuals living with chronic hepatitis B. ⁵ Factors contributing to the high prevalence include mother-to-child transmission, unsafe medical practices, and limited access to immunizations, testing, and treatment. ⁶ Pregnant women with hepatitis B face increased risks of liver problems, premature birth, and transmission of the infection to their infants, potentially leading to maternal and fetal death.^7,8 Furthermore, after childbirth, an infected mother might transfer hepatitis B to her baby, resulting in chronic hepatitis B infection in the infant. ⁹ This situation may lead to maternal and fetal death if not detected and treated promptly. ¹⁰

Sierra Leone is significantly affected, with a prevalence of 21.7% surpassing the global average.^1,11 Challenges such as insufficient public health infrastructure, limited healthcare access, and inadequate vaccine coverage contribute to the high prevalence. ¹² Pregnant women in Sierra Leone face a significant risk of HBV transmission, with studies indicating a prevalence of 13.0% ¹³ –21% ¹¹ in the general population. A recent study conducted in Tonkolili Province, Sierra Leone, revealed that the prevalence of hepatitis B surface antigen (HBsAg) was 15% among males and 13% among women who were screened as potential blood donors at a local hospital. ¹⁴ Moreover, another study revealed a prevalence rate of 10.0% for HBsAg infection among healthcare professionals in Freetown, Sierra Leone. All these studies indicate a significant level of hepatitis B infection within different population groups in Sierra Leone.^15,16 Pregnant women appear to be significantly affected by HBV, ¹⁶ and the likelihood of mother-to-child transmission during childbirth is grave. Generally, infants who acquire chronic hepatitis B from their mothers may face an elevated risk of developing liver cirrhosis and cancer later in life. ¹⁷ Similarly, a lack of awareness of HBV among pregnant women may contribute to inadequate preventive measures. This is evident in a few studies conducted in Sierra Leone reporting a lack of awareness about the extent of viral hepatitis B and C, despite a high burden. ¹¹

Sierra Leone, like many countries, often adheres to vaccination schedules and preventative measures for diseases such as hepatitis B as established by international health organizations such as the World Health Organization (WHO) and the US Centers for Disease Control and Prevention. However, it is important to note that the introduction of vaccination programs, including the HBV vaccine, can differ based on the availability of funds, the state of the infrastructure, and the national public health goals. Infants are usually vaccinated with the three-dose HBV series to prevent hepatitis B infection.^18,19 However, within Sierra Leone administration, Hepatitis B dose at birth (HepB-BD) is not recommended despite a high prevalence of HBV. The decision not to administer the hepatitis B vaccine at birth may reflect the vaccination strategy tailored to Sierra Leone’s specific public health needs and priorities. ¹⁹ The three doses of the HBV vaccine are usually given within 6, 10, and 14 weeks of delivery. ¹⁸

The HBV vaccination program has been in place for over a decade and many of the women presenting for antenatal care may have received the vaccine earlier in life. However, this would depend on the coverage and effectiveness of the vaccination program in the country. ²⁰ To enhance the general health outcomes for both the mother and the child, HBsAg screening at antenatal care clinics is often combined with other maternal health tests, such as HIV screening. Depending on the resources of healthcare institutions in various parts of Sierra Leone, HBsAg screening may not be offered in conjunction with prenatal HIV screening. It is therefore critical to assess HBV among pregnant women through serological markers to understand their current infection status or past exposure. Successful strategies to prevent hepatitis B transmission from mother to child during pregnancy are dependent on a thorough understanding of these characteristics. This study assessed the proportion of pregnant women with HBsAg, hepatitis B antigen status, and risk factors for HBV infection among pregnant women in the Western Area Urban (WAU) of Sierra Leone. These findings may apply to pregnant women in Sierra Leone and other low- and middle-income countries with comparable healthcare systems, socioeconomic conditions, and cultural practices.

Material and methods

Study design and population

We conducted a facility-based cross-sectional study to estimate the proportion of hepatitis B infection and determine the factors associated with HBV infection among pregnant women attending antenatal clinics (ANC) in the WAU District of Sierra Leone (Figure 1).

Figure 1.

Map of Sierra Leone showing project intervention site.

The facilities include Aberdeen Women’s Centre (AWC), Princess Christian Memorial Hospital (PCMH), King Harman Road Government Hospital (KHRGH), Lumley Government Hospital (LGH), and Rokupa Government Hospital (RGH). These facilities were randomly selected from among nine high ANC attendance facilities in the WAU District as part of the free healthcare initiative project. All pregnant women who received ANC services at the designated facilities in the WAU District in May 2021 were considered for enrollment.

According to the Sierra Leone 2015 Population and Housing Census Thematic Report on Population Projections, ²¹ WAU had an estimated population of 1,232,278 people, of which 349,104 (28%) were of childbearing age (15–49 years). In Sierra Leone’s WAU District, there are 62 health facilities, 55 peripheral health units, ¹⁷ and nine referral hospitals.^22,23 Pregnant women attending ANC at five randomly selected secondary hospitals participated in the study: AWC, PCMH, KHRGH, LGH, and RGH. These facilities were chosen at random from among nine high ANC attendance facilities in the WAU District as part of the free healthcare project. All pregnant women who received ANC services at the designated facilities in the WAU in May 2021 were considered for enrollment. Prior to the study, an estimated 41,787 ANC attendance was recorded in the five selected hospitals (Figure 1).

Inclusion and exclusion criteria

The study included all pregnant women of any gestational age who accepted to participate in the study and were receiving ANC care at the specified hospitals in the WAU. All pregnant women whose clinical data was not available and who had health conditions required immediate medical attention were excluded from the research. Pregnant women who refused consent to participate in the study were also excluded from the study.

Data collection tools and procedure

A structured questionnaire was utilized to gather data on various sociodemographic factors, including age, religion, marital status, education, occupation, and income. In addition, we collected information on obstetric and reproductive factors, such as gravidity, parity, antenatal care follow-up, previous delivery location, stillbirths, abortions, sexual orientation, and the HBV status of family members. Clinical factors, including HBV status, vaccination history, HIV status, hospital admissions, surgeries, blood transfusions, and sexually transmitted infections, were also collected. Finally, we collected information on risky practices, such as sharing toothbrushes, tattooing, and unsafe injection practices.

Face-to-face interviews were conducted using mobile tablets and Epi-Info 7.2 software. ²⁴ The presence of HBsAg in blood samples was evaluated using the real-time HBV 5-in-1 Combination Panel Test. All blood samples were processed following standardized testing methodologies to ensure consistent evaluation of HBV infection status across all groups. Each enrolled woman received a free HBV test, and the results were kept confidential. Data collected from the tablets was downloaded to the lead researcher’s secure system at the end of each day to maintain participants’ privacy. Regular data backups were also password-protected. The figure below illustrates the procedures for data collection (Figure 2). ²⁵

Figure 2.

Process flow chart for the selection of pregnant.

Hepatitis B serologic markers and testing

A real-time HBV 5-in-1 Combination Panel Test (a rapid, qualitative immunoassay) which detected HBsAg in blood specimens was used. This kit was used because it quickly and accurately detects hepatitis B indicators (HBsAg, hepatitis B surface antibody (HBsAb), hepatitis B e antigen (HBeAg), hepatitis B e antibody (HBeAb), hepatitis B core antibody (HBcAb)) in blood or plasma, thus aiding hepatitis B clinical evaluation.^25,26 The HBsAg signifies an active HBV infection, whether acute or chronic. HBsAg presence served as the main indicator for categorizing subjects as HBV-infected. The HBsAb or anti-HBs signifies recovery from HBV infection or effective vaccination. The lack of HBsAb and the presence of HBsAg confirmed active infection. Conversely, HBeAg indicates vigorous viral replication and increased infectivity. A positive HBeAg was used to evaluate the severity of current infection. Furthermore, HBeAb or anti-HBe facilitates a decrease in viral replication and diminishes infectivity. A positive HBeAb with persistent HBsAg indicates a shift to a less replicative phase in chronic infection. The HBcAb or Anti-HBc serves as a marker for previous or current infection. The distinction between IgM Anti-HBc (indicative of acute infection) and IgG Anti-HBc (indicative of chronic or resolved infection) was essential for categorization. ²⁷

Due to its importance in understanding HBV infection’s natural history and clinical evolution, we included HBeAb in our analysis even though it is seldom employed in clinical decision-making or research. The 5-in-1 Combination Panel Test was manufactured by Henso Medical (Hangzhou) Co., Ltd. (Hangzhou, People’s Republic of China). ²⁷ Below are the operational definitions of the respective tests conducted. Table 1 provides the operational definitions of serologic markers of hepatitis B, its interpretation, and how the classifications are applied in this study. ²⁸

Table 1.

Operational definitions of hepatitis B blood tests conducted.

Serologic marker	Interpretation	Classification used in this study
HBsAg positive	Active HBV infection	Counted as infected
HBsAb positive	Immunity (past infection or vaccination)	Not infected
HBeAg positive	High viral replication	Described as high infectivity
HBeAb positive	Reduced viral replication	Supporting marker
HBcAb positive (IgG)	Past/chronic infection	Supporting marker

HBcAb: hepatitis B core antibody; HBeAb: hepatitis B e antibody; HBeAg: hepatitis B e antigen; HBsAb: hepatitis B surface antibody; HBsAg: hepatitis B surface antigen; HBV: hepatitis B virus.

Study variables

The main outcome was HBV infection, both acute and chronic. The presence of specific serologic markers was used to determine HBV infection in the study through laboratory testing. These markers offered information regarding the individual’s immune response status and whether the infection was acute, chronic, or resolved. We used clinical and serologic profiling in the handling of acute versus chronic cases. Acute infection was indicated by elevated levels of HBeAg and IgM Anti-HBc, while chronic infection was differentiated using HBeAb, IgG Anti-HBc, and the absence of IgM Anti-HBc. ²⁷ The exposure variables included sociodemographic, clinical, and behavioral practice, which might affect or predict the outcome. The study took into account variables like age and socioeconomic level as possible factors that could change the results. Additionally, effect modifiers like the nature of marriage and sexual preference were also considered.

Sample size and sampling approach

The sample size was estimated using Cochran’s formula for a single population proportion ²⁹ :

$$\mathrm{n=}\frac{{\mathrm{Z}}^2\mathrm{pq}}{{\mathrm{d}}^2}$$

Where n = estimated sample size; Z = the constant for a 95% confidence interval (CI) given as 1.96; p = the average prevalence of HBV infection taken as 18.8% among pregnant women in Sierra Leone ≡ (p = 0.188); d = the % margin of error taken as 5% = 0.05; q = (1 − p) = 0.812 and n = 235. The sample size was increased by 25% to account for nonresponse or incomplete surveys. This sample was proportionately spread across the five study sites, according to the facility’s 2020 ANC attendance data.

Statistical analysis

The dataset was analyzed using STATA IC version 16 (Stata Statistical Software, version 16; Stata Corp LLC, College Station, TX, USA). Baseline clinical and demographic factors were summarized using descriptive statistics, whereby frequencies and percentages were reported for categorical data and median with interquartile range for continuous data. Descriptive statistics were also performed based on variables from the questionnaire. Measures of central location, such as mean, and measures of dispersion, such as standard deviations and interquartile were calculated for continuous variables in the questionnaire. Odds ratios (ORs) and chi-square analysis were performed to test for significant associations among the different independent and dependent variables. For all the analyses, data were considered statistically significant at a p < 0.05, and 95% CIs were estimated. The prevalence of HBV infection and hepatitis B antigens, as well as their combinations, were estimated and visualized using bar charts. HBV current infection was compared across four HBV antigen statuses using Pearson’s and Fisher’s exact chi-square tests as appropriate.

A binary logistic regression model was used to estimate crude and adjusted ORs (AORs) for factors associated with HBV infection. To find variables for the final model in the multivariable analysis, we applied a stepwise selection technique, more precisely, a forward-backward selection method. Variables that were significant at 0.100 from the bivariate analysis were considered in the final model. In the forward stage, factors that were significant criteria were included one after the other, and in the backward step, variables that did not meet significance when additional covariates were included were eliminated or removed. The health facility variable was, however, excluded as it showed high multicollinearity, and the model goodness of fit test was poor. The final model goodness of fit assessment attained a nonsignificant p value of 0.903, indicating appropriateness of the model. Multicollinearity was assessed using the variance inflation factor, attaining a mean value of 2.48 (range: 1.30–4.73), which is below 5, indicating a reasonable level of multicollinearity between independent variables. p < 0.05 was deemed to be statistically significant for all statistical analyses.

Possible limitations and mitigation strategies

The study anticipated potential bias and the following measures were taken to mitigate these sources of bias:

Only pregnant women who visited ANC in five secondary hospitals within a single urban district (WAU, Sierra Leone) were included in the study. Pregnant women in rural areas or those who do not attend ANC may not be fully represented in this sample. Random sampling was used to choose only referral hospitals within the district, ensuring that study participants from both urban and rural areas within the district were represented in an effort to mitigate potential sources of bias. Similarly, recall Bias where participant memory may result in inaccurate self-reported information on risk factors, such as sharing toothbrushes, tattoos, and prior medical history (such as stillbirth). When feasible, self-reports were cross-checked with respondents’ medical records in an attempt to mitigate recollection bias. Moreover, misclassification, or information bias of HBV status, may result from testing solely for serological markers (HBsAg, HBsAb, HBeAg, HBeAb, and HBcAb) without differentiating between acute and chronic infections. Although the study aimed to differentiate between acute and chronic HBV infection, this was not feasible due to the unavailability of confirmatory IgM Anti-HBc and HBV DNA testing during the study period. Notably, the research was conducted at the peak of the COVID-19 pandemic in Sierra Leone, a time when laboratory resources and healthcare services were severely constrained. These challenges limited our ability to perform comprehensive HBV diagnostic testing. Consequently, all individuals who tested positive for HBsAg were classified as having HBV infection, without distinguishing between acute and chronic forms. Whereas the study offers insightful information into HBV prevalence and risk factors among pregnant women, talking the above biases through enhanced study design, data collection, and analytical methods will improve the validity and generalizability of future findings.

Ethical approval

Our study adhered to existing rigorous ethical standards, including obtaining appropriate approvals and consent from participants. Extension of ethics approval was obtained from the Sierra Leone Ethics and Scientific Review Committee with ethic number (016/12/2024).

All eligible pregnant women seeking ANC services were provided information an out the study before recruitment. All study participants provided written informed consent prior to their inclusion in the research. For individuals within the age range of 15–17 years, consent was obtained from their guardians/mother and assent from the individual. In addition, we also followed the STROBE guidelines in preparing the article to enhance quality and standard. Benefit to participants: participants received education on hepatitis B infection prevention and control measures and, at the same time were tested on a cost-free basis.

Results

Sociodemographic characteristics and HBV status of pregnant women

A total of 320 pregnant women were participated in this study, and the median age of the respondents was 25 years with interquartile range of 22–29 years. Of the five facilities, about one-third (32.2%) of respondents were from the PCMH, 20.6% from the AWC, 14.7% from the KHRGH, 14.1% from the LGH, and 18.4% from the RGH. The median age of the respondents was 25 years with an interquartile range of 22–29 years with (32.8%) of the age ranged 25–29 years and (29.1%) ranged 20–24 years.

The proportion of HBV infection was significantly higher in LGH (28.9%, 95% CI: 17.5–43.7) compared to AWC (16.7%, 95% CI: 9.5–27.7), KHRGH (8.5%, 95% CI: 3.2–20.6), PCMH (12.6%, 95% CI: 7.5–20.6), and RGH (5.1%, 95% CI: 1.6–14.7) HBV infection was significantly higher among unmarried pregnant women (20.4%, 95% CI: 13.9–28.8) compared to married pregnant women (10.1%, 95% CI: 6.7–15.1). The type of marriage was also significantly associated with the proportion of HBV infection among the pregnant p = 0.020) with a lower proportion of infection among pregnant women in monogamous marriage (8.8%, 95% CI: 9.9–19.7) compared to pregnant women in polygamous marriage (16.2%, 95% CI: 9.6–31.2). Pregnant women with no formal education (20.0%, 95% CI: 11.4–32.7) and primary education (37.1%, 95% CI: 22.9–54.0) had a greater proportion of HBV infection than pregnant women with secondary (16.3%, 95% CI: 10.2–25.0) and tertiary (9.9%, 95% CI: 5.8–16.4) education. Religion, wealth, occupation, or age group did not differ by HBV infection (Table 2).

Table 2.

Sociodemographic characteristics and HBV infection among pregnant.

Characteristics	Total, N (%)	HBsAg status		95% CI of HBsAg positive
		Positive, N/(%)	Negative, N/(%)
N	320 (100%)	44 (13.8)	276 (86.3)	10.4–18.0
Health facility
AWC	66 (20.6)	11 (16.7)	55 (83.3)	9.5–27.7
KHRGH	47 (14.7	4 (8.5)	43 (91.5)	3.2–20.6
LGH	45 (14.1)	13 (28.9)	32 (71.1)	17.5–43.7
PCMH	103 (32.2	13 (12.6)	90 (87.4)	7.5–20.6
RGH	59 (18.4)	3 (5.1)	56 (94.9)	1.6–14.7
Religion
Christian	143 (44.7)	19 (13.3)	124 (86.7)	8.6–19.9
Muslim	177 (55.3)	25 (14.1)	152 (85.9)	9.7–20.1
Age group (years)
15–19	46 (14.4)	8 (17.4)	38 (82.6)	8.9–31.2
20–24	93 (29.1)	9 (9.7)	84 (90.3)	5.1–17.6
25–29	105 (32.8)	17 (16.2)	88 (83.8)	10.3–24.5
30–34	46 (14.4)	5 (10.9)	41 (89.1)	4.6–23.6
35–39	25 (7.8)	5 (20.0)	20 (80.0)	8.5–40.1
40–44	5 (1.6)	0 (0.0)	5 (100.0)
Marital status
Married	207 (64.7)	21 (10.1)	186 (89.9)	6.7–15.1
Single	113 (35.3)	23 (20.4)	90 (79.6)	13.9–28.8
Type of marriage
None	113 (35.3)	23 (20.4)	90 (79.6)	6.2–24.4
Monogamous	170 (53.1)	15 (8.8)	155 (91.2)	9.9–19.7
Polygamous	37 (11.6)	6 (16.2)	31 (83.8)	9.6–31.2
Education level
None	55 (17.2)	11 (20.0)	44 (80.0)	11.4–32.7
Primary	35 (10.9)	13 (37.1)	22 (62.9)	22.9–54.0
Secondary	172 (53.8)	15 (8.7)	157 (91.3)	5.3–14.0
Tertiary	58 (18.1)	5 (8.6)	53 (91.4)	3.6–19.1
Husband or spouse’s education level
None	53 (16.6)	7 (13.2)	46 (86.8)	6.4–25.3
Primary	12 (3.8)	2 (16.7)	10 (83.3)	4.2–47.9
Secondary	98 (30.6)	16 (16.3)	82 (83.7)	10.2–25.0
Tertiary	131 (40.9)	13 (9.9)	118 (90.1)	5.8–16.4
Occupation
Civil or public servant	70 (21.9)	8 (11.4)	62 (88.6)	5.8–21.3
Others (specify)	36 (11.3)	5 (13.9)	31 (86.1)	5.9–29.4
Petty trader	135 (42.2)	23 (17.0)	112 (83.0)	11.6–24.4
Student	44 (13.8)	4 (9.1)	40 (90.9)	3.4–21.9
Unemployed	35 (10.9)	4 (11.4)	31 (88.6)	4.3–26.8
Income per month (Leones)
<600,000	197 (61.6)	32 (16.2)	165 (83.8)	11.7–22.1
600,000–1,000,000	69 (21.6)	6 (8.7)	63 (91.3)	3.9–18.1
>1,000,000	54 (16.9)	6 (11.1)	48 (88.9)	5.1–22.7

AWC: Aberdeen Women’s Centre; HBsAg: hepatitis B surface antigen; HBV: hepatitis B virus; KHRGH: King Harman Road Government Hospital; LGH: Lumley Government Hospital; PCMH: Princess Christian Memorial Hospital; RGH: Rokupa Government Hospital.

Hepatitis B infection among pregnant women

The proportion of hepatitis B infection (HBsAg positive) was 13.8% among the 320 pregnant women with a 95% CI estimate of 10.2%–18.0%. Only a small proportion of the women (6/320; 95% CI: 0.70%–4.0%) tested positive for HBsAb. In contrast, a large proportion of pregnant women tested positive for HBeAb (91.3%, 95% CI: 87.6%–94.1%) and HBcAb (85.3%, 95% CI: 81.0%–89.0%; Table 3).

Table 3.

Proportion of hepatitis B infection and hepatitis B antigen status among pregnant women.

HBV outcome	Total	Positive	Negative	95% CI of positivity
HBsAg (hepatitis B current status)	320	44 (13.8)	276 (86.3)	10.2–18.0
HBsAb	320	6 (1.9)	314 (98.1)	0.7–4.0
HBeAg	320	31 (9.7)	289 (90.3)	6.7–13.5
HBeAb	320	292 (91.3)	28 (8.8)	87.6–94.1
HBcAb	320	273 (85.3)	47 (14.7)	81.0–89.0

HBcAb: hepatitis B core antibody; HBeAb: hepatitis B e antibody; HBeAg: hepatitis B e antigen; HBsAb: hepatitis B surface antibody; HBsAg: hepatitis B surface antigen; HBV: hepatitis B virus.

The proportion of HBsAg by HBsAb, HBeAg, HBeAb, and HBcAb antigens status among pregnant women

The proportion of HBsAg-positive among HBsAb negatives was significantly lower (13.1%) than the percentage of HBsAg-positive among HBsAb positives (50.0%; 95% CI: 0.45–0.55). The proportion of HBsAg-positive among HBeAg negatives (8.0%) was similarly significantly lower than the proportion of HBsAg-positive among HBeAg positives (67.7%; 95% CI: 0.63–0.73) In contrast, the percentage of HBsAg-positive among HBeAb negatives was 64.3%, which was significantly higher than the percentage of HBV infections among HBeAb positives (8.9%; 95% CI: 0.06–0.12). Furthermore, the percentage of HBV infections among HBcAb negatives (48.9%) was significantly greater (95% CI: 0.05–0.11) than the percentage of HBV infections among HBcAb positives (7.7%; Table 4).

Table 4.

Prevalence of HBsAg ^a by HBsAb ^b , HBeAg ^c , HBeAb ^d , and HBcAn among pregnant women.

BHV seromarkers	Hepatitis B status		95% CI of antigens status
Antigens	Positive, n/N (%)	Negative, n/N (%)
HBsAb
Negative	41/314 (13.1%)	273/314 (86.9%)	0.45–0.55
Positive	3/6 (50.0%)	3/6 (50.0%)
HBeAg
Negative	23/289 (8.0%)	266/289 (92.0%)	0.63–0.73
Positive	21/31 (67.7%)	10/31 (32.3%)
HBeAb
Negative	18/28 (64.3%)	10/28 (35.7%)	0.06–0.12
Positive	26/292 (8.9%)	266/292 (91.1%)
HBcAb
Negative	23/47 (48.9%)	24/47 (51.1%)	0.05–0.11
Positive	21/273 (7.7%)	252/273 (92.3%)

HBcAb: hepatitis B core antibody; HBeAb: hepatitis B e antibody; HBeAg: hepatitis B e antigen; HBsAb: hepatitis B surface antibody; HBsAg: hepatitis B surface antigen.

^aA positive HBsAg result means you have an active hepatitis B virus infection.

^bIt detects proteins that are made by the immune system.

^cHepatitis B viral protein, produced by the HBcAg reading frame.

^dHBeAb or Anti-HBe.

Reproductive characteristics and HBV status of pregnant women

The prevalence of HBV infection among pregnant women varied according to multiple factors in the current study. Pregnant women without a history of stillbirth had a greater rate of HBV infection (15.4%, 95% CI: 11.6–20.2) than those with a history of stillbirth (4.3%, 95% CI: 1.1–15.6). Similarly, women who had several sexual partners had a greater prevalence of HBV infection (26.3%, 95% CI: 16.5–39.2) than those who did not have multiple sexual relationships (11.0%, 95% CI: 7.8–15.4). Also, some behaviors were related to increased HBV infection rates in pregnant women. Those who swapped toothbrushes with family or friends had a higher proportion of HBV infection (19.0%, 95% CI: 13.5–26.2) than those who did not (9.5%, 95% CI: 5.3–16.3). Pregnant women who had ever had a tattoo on their body had a significantly greater proportion of HBV infection (24.1%, 95% CI: 15.9–34.7) than women who had never had a tattoo (10.4%, 95% CI: 7.1–14.9). Pregnant women’s sexual orientation was also related to HBV infection. When compared to heterosexual women (11.0%, 95% CI: 7.8–15.4), bisexual women had a considerably greater proportion of HBV infection (26.3%, 95% CI: 16.5–39.2). The findings also show that pregnant women with a history of hazardous injections had a greater proportion of HBV infection (18.4%, 95% CI: 13.4–24.8) as compared to those who had no history of unsafe injections (6.8%, 95% CI: 2.6–16.8; Table 5).

Table 5.

Reproductive characteristics and HBV infection among pregnant women.

Characteristics	Total	HBsAg status		95% CI of HBsAg positive
		Positive	Negative
Gravidity
Primigravida	68	8 (11.8)	60 (88.2)	6.0–21.9
Multigravida	252	36 (14.3)	216 (85.7)	10.5–19.2
Age at first pregnant (years)
<18	72	10 (13.9)	62 (86.1)	7.6–24.0
At 18	50	13 (26.0)	37 (74.0)	15.7–39.9
>18	198	21 (10.6)	177 (89.4)	7.0–15.7
Previous history of stillbirth
No	273	42 (15.4)	231 (84.6)	11.6–20.2
Yes	47	2 (4.3)	45 (95.7)	1.1–15.6
Multiple sexual partner
No	282	39 (13.8)	243 (86.2)	10.3–18.4
Yes	38	5 (13.2)	33 (86.8)	5.6–28.0
Sexual orientation
Heterosexual	263	29 (11.0)	234 (89.0)	7.8–15.4
Bisexual	57	15 (26.3)	42 (73.7)	16.5–39.2
History of hospital admission and surgery
No admission	230	30 (13.0)	200 (87.0)	9.3–18.1
Admission no surgery	37	3 (8.1)	34 (91.9)	2.6–22.4
Admission and surgery	53	11 (20.8)	42 (79.2)	11.9–33.8
Ever had a blood transfusion
No	270	35 (13.0)	235 (87.0)	9.4–17.5
Yes	50	9 (18.0)	41 (82.0)	9.6–31.2
Ever exchanged toothbrushes with family or friends
No	116	11 (9.5)	105 (90.5)	5.3–16.3
Yes	147	28 (19.0)	119 (81.0)	13.5–26.2
Don’t know	57	5 (8.8)	52 (91.2)	3.7–19.5
Ever had a tattoo on your body
No	241	25 (10.4)	216 (89.6)	7.1–14.9
Yes	79	19 (24.1)	60 (75.9)	15.9–34.7
History of unsafe sharing of equipment or re-use of needles
No	59	4 (6.8)	55 (93.2)	2.6–16.8
Yes	179	33 (18.4)	146 (81.6)	13.4–24.8
Don’t know	82	7 (8.5)	75 (91.5)	4.1–16.9

HBsAg: hepatitis B surface antigen; HBV: hepatitis B virus

Factors associated with HBV infection among pregnant women

The adjusted binary logistic regression model showed significant associations between HBV infection and various factors among pregnant women. Single pregnant women had three times higher odds of HBV infection compared to married pregnant women (AOR: 3.05, 95% CI: 1.29–7.22). Similarly, pregnant women with no formal education were three or more times more likely to be infected with HBV (AOR: 3.69, 95% CI: 1.33–10.22, p = 0.012), and those with primary education eight times more likely to be infected with HBV (AOR: 8.30, 95% CI: 2.69–25.63) of HBV infection compared to those with secondary education.

Pregnant women with a previous history of stillbirth had significantly lower odds of HBV infection compared to those without such a history (AOR: 0.20, 95% CI: 0.04–0.99; Table 6).

Table 6.

Factors associated with HBV infection among pregnant women.

Characteristics	Total	HBV status		Unadjusted logistic regression model	Adjusted logistic regression model
		Positive	Negative	COR (95% CI)	AOR a (95% CI)
N	320	44 (13.8)	276 (86.3)
Type of marriage
None/ Not married	113	23 (20.4)	90 (79.6)	2.64 (1.31–5.32)	3.05 (1.29–7.22)
Monogamous	170	15 (8.8)	155 (91.2)	1.00 (reference)	1.00 (reference)
Polygamous	37	6 (16.2)	31 (83.8)	2.00 (0.72–5.56)	1.80 (0.55–5.88)
Education level
None	55	11 (20.0)	44 (80.0)	2.62 (1.12–6.10)	3.69 (1.33–10.22)
Primary	35	13 (37.1)	22 (62.9)	6.18 (2.60–14.71)	8.30 (2.69–25.63)
Secondary	172	15 (8.7)	157 (91.3)	1.00 (reference)	1.00 (reference)
Tertiary	58	5 (8.6)	53 (91.4)	0.99 (0.34–2.85)	1.08 (0.33–3.61)
Age at first pregnant (years)
<18	72	10 (13.9)	62 (86.1)	1.00 (reference)	1.00 (reference)
At 18	50	13 (26.0)	37 (74.0)	2.18 (0.87–5.46)	3.24 (0.86–12.14)
>18	198	21 (10.6)	177 (89.4)	0.74 (0.33–1.65)	2.49 (0.83–7.48)
Previous history of stillbirth
No	273	42 (15.4)	231 (84.6)	1.00 (reference)	1.00 (reference)
Yes	47	2 (4.3)	45 (95.7)	0.24 (0.06–1.05)	0.20 (0.04–0.99)
Sexual orientation
Heterosexual	263	29 (11.0)	234 (89.0)	1.00 (reference)	1.00 (reference)
Bisexual	57	15 (26.3)	42 (73.7)	2.88 (1.42–5.83)	1.77 (0.51–6.15)
Ever exchanged toothbrushes with family or friends
No	116	11 (9.5)	105 (90.5)	1.00 (reference)	1.00 (reference)
Yes	147	28 (19.0)	119 (81.0)	2.25 (1.07–4.73)	1.37 (0.55–3.37)
Don’t know	57	5 (8.8)	52 (91.2)	0.92 (0.30–2.78)	0.75 (0.20–2.83)
Ever had a tattoo mark on your body
No	241	25 (10.4)	216 (89.6)	1.00 (reference)	1.00 (reference)
Yes	79	19 (24.1)	60 (75.9)	2.74 (1.41–5.30)	2.09 (0.83–5.29)
History of unsafe injections
No	179	33 (18.4)	146 (81.6)	1.00 (reference)	1.00 (reference)
Yes	59	4 (6.8)	55 (93.2)	0.32 (0.11–0.95)	0.21 (0.06–0.78)
Don’t know	82	7 (8.5)	75 (91.5)	0.41 (0.17–0.98)	0.68 (0.21–2.16)
Willingness to undergo further tests if diagnosed with hepatitis B
No	51	14 (27.5)	37 (72.5)	1.00 (reference)	1.00 (reference)
Yes	192	23 (12.0)	169 (88.0)	0.36 (0.17–0.76)	0.62 (0.19–2.00)
Don’t know	77	7 (9.1)	70 (90.9)	0.26 (0.10–0.71)	0.78 (0.17–3.48)
Model assessment
Goodness of fit test p value					0.9027
VIF (range)					2.48 (1.30–4.73)

COR: crude odds ratio; AOR: adjusted odds ratio; VIF: variance inflation factor.

^aAOR: all variables that were significant at the bivariate level were included in the final model.

Bold values indicate that the variable is statistically significant at p < 0.05.

Discussion

Prevalence of HBV infection and HBV sero-markers

This study assessed the prevalence of HBV infections among 320 pregnant women from five different healthcare facilities. The majority of the participants were young, with a median age of 25 years. The distribution of pregnant women differs by hospital, with the PCMH making the biggest input.

Our study revealed a high prevalence of hepatitis B (HBsAg positive) infection among pregnant women in the WAU District. Even though a system review in Sierra Leone showed a steady decrease in HBV among the general population in the last 25 years, ¹⁴ the prevalence identified does exceed the WHO’s recommended high prevalence criterion (>8%). ²⁸ This observed high prevalence aligns with reports from a previous study conducted in Sierra Leone in 2020, which reported high rates (11.3%) of HBV infection among similar populations in 2020. ¹¹ However, our study prevalence was higher than a similar study conducted in the Gambia (9.20%), ³⁰ Northwest Ethiopia, where 16 (4.7%) of respondents were positive for HBV infection. ⁶ The variation in prevalence between the two studies could stem from differences in study population characteristics. Our study exclusively gathered data from five referral facilities, whereas the study in Northwest Ethiopia focused on data collection in a single referral facility. In addition, a different geographical location may also influence HBV prevalence distribution. Studies in sub-Saharan Africa show that West African countries have been reported to have high HBV prevalence and Sierra Leone is one of them.^11,16,31 Others including Nigeria and Liberia have been identified as having high HBV prevalence rates in Africa. ³²

A significant proportion of pregnant women had antibodies against the HBeAb and the HBcAb, suggesting past exposure to the virus, even if they were not currently infected (HBeAg positive). ³³ Only a few pregnant women in our population, 1.9%, tested positive for HBsAb, indicating low immunity against the virus. The low prevalence of HBsAb-positive pregnant women raises concerns about immunity against hepatitis B, highlighting the need to protect pregnant women to reduce the risk of Mother-to-Child Transmission. ⁹

While our findings indicate a similar prevalence of HBV in pregnant women with the overall HBV prevalence in the general population, ³¹ some studies have reported that pregnant women negative for HBsAg, HBsAb, and HBeAg but positive for HBeAb and HBcAb showed higher HBeAg seroprevalence. ¹¹ These individuals lack protective antibodies, potentially indicating prior hepatitis B infection that has been controlled, reducing the risk of chronic infection and vertical transmission from mother to child. ³³ Our findings differ from Adegbesan-Omilabu et al. finding, which has reported a much higher HBeAg seroprevalence rate of 36.4%, among pregnant women in Nigeria.^11,34 High HBeAg seroprevalence rates may suggest a higher risk of passing the virus to infants during childbirth. Current evidence indicates that the presence of HBeAg in pregnant women enhances the likelihood of vertical transmission.^35,36

Sociodemographic characteristics of HBV infection among pregnant women

This study highlights the different frequencies of HBV infection among pregnant women in the WAU District of Sierra Leone across age groups, marital status, and educational levels. The study findings indicate that pregnant women between the ages of 35 and 39 had a higher proportion of HBsAg. These findings suggest not only a lack of knowledge about their condition, given that HBV testing is not mandatory in Sierra Leone. ³⁷ It also suggests a potential association between older age and increased HBV infection risk, which may be attributed to factors such as cumulative lifetime exposures and delays in accessing healthcare services. Our finding contrasts reports of 15% HBsAg among pregnant women aged 35–40 years in Ethiopia, ³⁸ and 14% in pregnant women aged 26–30 years in South Sudan. ³⁹ A similar study conducted in Ghana shared no such association in the age of study participants. ⁴⁰

Our results revealed also that single pregnant women were more likely to contract HBV than married women. This finding may be because married women may have a permanent sexual partner which may reduce their chances of HBV infection. This reasoning is supported by a study among pregnant women in Ethiopia, which found that women with multiple sexual partners were almost seven times more likely to be HBV-positive than those without multiple partners. ⁴¹ Having multiple sexual partners could imply that the woman has limited or no control over their partners’ sexual behaviors, hence increasing the woman’s risk for HBV infection. The results of our study on the relationship between marital status and the likelihood of HBV infection differ from a seroprevalence study conducted on pregnant women in Central Nigeria. This study found a prevalence rate of 14 (5.6) HBV infections among polygamous pregnant women compared to 8 (5.3) among monogamous pregnant women.^38,42 Their findings align with reports from the research conducted by Eyong et al., which likewise found that the rate of HBV infection was 30% higher among polygamous pregnant women compared to 4.7% in monogamous pregnant women. ³⁴ The disparity between our research and the two studies may be attributed to the influence of study methodologies and cultural practices shown by the study participants.

However, their study aligns with our findings, where their study also found that pregnant women without formal education were more likely to get infected with HBV, indicating that education may help lower the risk of infection.^38,42 Preliminary results from the 2018 Sierra Leone integrated household survey, which indicate widespread poverty in Sierra Leone, show that the majority of the women from our study population earned <$60/month on average. ³² This suggests that women with lower incomes may be unable to afford preventive healthcare treatments such as vaccinations and frequent checkups. Women who are resource-constrained may also partake in social activities that expose them to blood and bodily fluids, increasing their risk of HBV infection. ⁴³

Risk factors of HBV infection among pregnant women

Many risk factors, such as a sharing toothbrushes, obtaining tattoos, and hazardous injections, were associated with an increased risk of HBV infection among pregnant women in this study. This finding is important since prenatal hepatitis B infection increases the likelihood of premature delivery, as evidenced by Liu et al.’s ⁴⁴ report of a 34% increased incidence of preterm birth in pregnant women who were both HBsAg and HBeAg positive. ³³

To fully characterize HBV infection in our study, we investigated HBeAb together with other HBV markers. HBeAb is important for understanding HBV development. We measured HBeAb status to describe the immune response and assess disease prognosis. For instance, most pregnant women (91.3%) tested positive for HBeAb in our study, suggesting a good HBV prognosis. This change from active replication to HBeAb, whether spontaneous or treatment-induced, is typically advantageous. ²⁶

Pregnant women with no history of stillbirth in the present study were more likely to have HBV infection than pregnant women who had experienced stillbirth in the past. This finding could imply that the women who had no history of stillbirth may be in their first pregnancies, which aligns with reports from a study done by Lamont et al. in three countries. They observed that women who had a stillbirth in their first pregnancy had a higher likelihood of experiencing another stillbirth in future pregnancies, compared to women who had a live delivery (adjusted hazard ratio 2.25, 95% CI: 1.86–2.72). ⁴⁵ A possible explanation for this occurrence could be that women who had stillbirths in the past may have more frequent interactions with healthcare providers, ensuring better monitoring and early detection of health conditions, including HBV infection.^36,46 On the other hand, women who have never had a stillbirth may have presumed that they were healthy during their pregnancy, and they may have put themselves at greater risk of contracting HBV if they did not have frequent checks.

Pregnant women who shared toothbrushes with family or friends had a greater chance of contracting HBV. While being affectionate, this behavior can result in several infections, including HBV. Kiros et al. reported similar results in a study conducted in the Tigray Region, Northern Ethiopia. ⁴⁷ The investigators reported a 3.8% probability of HBV infection among mothers who shared personal effects, including toothbrushes. ⁴⁷ Another study discovered similar patterns among medical and nonmedical undergraduate students, with 23% of toothbrush sharing indicated as a risk factor. ⁴⁰ Sharing a toothbrush with others can have a variety of implications, and it is generally discouraged due to health and hygiene concerns. ⁴¹

We observed that pregnant women who had tattoos were more likely to have HBV infection than those who did not. The result of this study is consistent with the seroprevalence study of HBV among pregnant women in public hospitals in Hawassa City, Southern Ethiopia. The study identified tattoo practice associated with HBsAg seropositivity (AOR = 6.822; 95% CI: 1.89–24.69).^47,48 This could be due to the use of contaminated tattooing instruments or poor tattoo-infection control strategies, which increase the risk of HBV infection. Tattooing is a popular social activity common among young women even before becoming pregnant. ¹¹ A comparable study conducted at 10 Community Health Centers in Freetown, Sierra Leone. reported that tattoo prevalence was 11.4% (45/394) among pregnant women. ¹⁶ Similarly, recent research in Ethiopia’s Northwest Region highlighted a history of body tattooing as one of the significant risk factors associated with HBV seropositivity among pregnant women. ⁶

Study limitations

Since this investigation was cross-sectional, a temporal relationship between the risk factors and HBV infections could not be established, limiting any causal interpretation of our findings. Given that participants were drawn from only five secondary hospitals in one region, our findings may not apply to pregnant women in other districts, women attending other health facilities, women with different cultural practices, or women with different risk profiles. The inability to distinguish between acute and chronic Hepatitis B infections among this study population is one of the study’s limitation. Due to the cross-sectional study design, there was not enough time to track the disease’s development over time. Similarly, IgM anti-HBc testing, which is a crucial indicator for differentiating between acute and chronic infections, was not easily accessible in Sierra Leone or in our labs throughout the study period. Hence, it was not included in the study. There is also a possibility of respondent bias among study participants, particularly in their responses to social risk factors for HBV infection. While this study was unable to provide treatment for pregnant women who tested positive for HBV, they were encouraged to seek treatment as soon as possible at their preferred health facility. Finally, because the study was conducted only in the WAU District of Sierra Leone, the findings cannot be generalized to the larger population of pregnant women in Sierra Leone, or women in the rural areas of the country. Further research in similar populations in both rural and urban settings of Sierra Leone will be required to establish risk factors for HBV in those populations.

Conclusion

This study found a high prevalence of hepatitis B (HBsAg positive) among pregnant women in Sierra Leone’s WAU District, much exceeding the WHO threshold. Education level, marital status, and unsafe practices such as tattooing and toothbrush sharing were significantly associated with HBV infection risk. The findings emphasize the urgent need for targeted public health interventions to reduce HBV transmission in this population. While these findings could contribute to developing a national plan to address viral hepatitis as a major public health issue among pregnant women by 2030, coordinated actions are needed right now to prevent infected women from passing the HBV virus on from mother to child. We also advocate for comprehensive health education on HBV exposure risk factors, as well as prompt treatment of HBV-infected pregnant women to prevent chronic HBV infection.