ABSTRACT

These findings demonstrate the prevalence of HBsAg among pregnant women and neonates born to HBsAg-positive mothers in Batman. Although HBsAg seropositivity rate among the pregnant women was found to be similar to the rates that were reported in other studies from the Southeastern Anatolian Region of Turkey. The fact that this rate was high for the neonates born to HBsAg-positive mothers was attributed to the insufficient immunoprophylaxis of the neonates. The identification and close follow-up of HBsAg-positive mothers is essential to make the complete and appropriate immunoprophylaxis in all neonates born to HBsAg-positive mothers and to prevent transmission of HBV.

The mean age of the pregnant women was 30.13±6.58 years. 15585 consecutive pregnant women were screened for HBsAg, retrospectively. HBsAg positivity rate was found to be 4.2% (668/15585) in the pregnant women while it was 20.5% (137/668) in neonates born to HBsAg-positive mothers between 6 to 9 months of age.

All pregnant women admitted to the obstetrics and gynecology unit between April 2008 and December 2010 were screened for HBsAg. Neonates born to HBsAg-positive mothers were also evaluated once for HBsAg seropositivity between 6 and 9 months of age. HBsAg presence was measured by the electrochemiluminescence immunoassay method using Modular analytics E170 analyser according to the manufacturer’s recommendations.

The aim of this study was to determine hepatitis B surface antijen (HBsAg) seroprevalence among pregnant women and neonates born to HBsAg-positive mothers admitted to Batman Gynecology, Obstetrics and Pediatrics Hospital located in Batman Province in, the Southeastern Anatolian Region of Turkey.

Introduction

Hepatitis B virus (HBV) infection is a major public health problem in the world. It is estimated that more than 350 million people are chronic HBV carriers worldwide. About 25% of them will develop chronic hepatitis or cirrhosis and may develop hepatocellular carcinoma, eventually (1). In the previous decade, the prevalence of HBsAg positivity has declined from 4.19% to 2.10% in Turkey. Despite this reduction, Turkey is still located in the intermediate endemic areas of HBV infection. It is known that HBV seroprevalence increases from the western to eastern parts of Turkey (2-12.5%). The vertical transmission is still a very important mode of HBV transmission, especially in high endemic areas (2). The prevalence of HBsAg positivity in pregnant women has been found to be between 2.1% and 16.6% in many epidemiologic clinical trials in Turkey (3). Mother-to-child transmission occurs often, either in utero or through exposure to blood or blood-contaminated fluids at or around birth (4). Such prenatal transmission can be prevented with the identification of HBsAg-seropositive women and administration of immunoprophylaxis to their newborns (1). Women with hepatitis have an increased risk for adverse perinatal outcome and pregnancy-related complications, and careful surveillance is warranted (5,6). HBV infection early in life usually results in chronic infection and 25% of these infected persons will die prematurely from cirrhosis and liver cancer (7). Thus, screening for HBsAg during pregnancy has gained importance and, prevention of vertical transmission by vaccination and immunoprophylaxis is critical (8). The aims of this study were to determine the rate of HBsAg seropositivity among pregnant women and neonates born to HBsAg-positive mothers in Batman, to compare the results with the data previously reported from other regions of the country and to add the data to the national epidemiological data.

Materials and Methods

We investigated the seroprevalence of HBsAg in 15585 pregnant women who were admitted to the obstetrics and gynecology unit between April 2008 and December 2010 in Batman Maternity Hospital. The mean age of participants was 30.13±6.58 years. HBsAg presence was measured from serum samples of pregnant women by an electrochemiluminescent immunoassay method using Modular Analytics E170 analyser (Roche Diagnostics GmbH, Mannheim, Germany) according to the manufacturer’s recommendations. The results were evaluated retrospectively. Newborn infants of HBV-positive mothers received both recombinant vaccine and hepatitis B immunoglobulin (HBIG) within 72 hours after delivery while neonates born to HBsAg-negative mothers received just recombinant vaccine in accordance with the universal vaccination programme of the Ministry of Health if the labor occurred in this hospital. Vaccine schedule was 0, 1 and 6 months. Neonates born to HBsAg-positive mothers were followed up and they were also screened once for HBsAg seropositivity between their 6 and 9 months of age by the same method.

Results

The mean age of the pregnant women was 30.13±6.58 years. 15585 consecutive pregnant women admitted to the Batman Gynecology, Obstetric and Pediatrics Hospital located in Batman Province were screened for HBsAg, retrospectively. HBsAg positivity rate was found to be 4.2% (668/15585) in pregnant women and 20.5% (137/668) in neonates born to HBsAg-positive mothers between their 6 and 9 months of age.

Discussion

HBV screening has been recommended by the Advisory Committee on Immunization Practices (AICP) for all pregnant women during an early prenatal visit in each pregnancy, even if they previously have been vaccinated or tested (9). HBV screening allows identification of infants requiring immunoprophylaxis with HBV vaccine and HBIG, antiviral treatment of pregnant carriers if indicated, and counseling of sexual and household contacts (10). Maternal screening programs and active and passive immunoprophylaxis have reduced transmission of HBV dramatically (11). However, 10-20% of children born to HBV carrier mothers, especially when the mother is highly viremic and HBeAg-positive, become HBsAg carriers, despite receiving active-passive immunoprophylaxis (9,10,11). It has been reported that the failure rate of the immunoprophylaxis was up to 28% in babies born to HBeAg-positive mothers (12). In a prospective study, HBV transmission rates were 3% from HBV DNA-positive mothers, 7% from HBeAg-positive mothers and 9% from mothers with high HBV DNA levels (12). Dwivedi et al. reported that only 0.9% (37/4000) of pregnant women were HBsAg-positive (13). Vertical transmission rate was 65% (13/20) in neonates born to mothers positive for HBeAg and HBV DNA, conversely, it was only 9.1% when the mothers were HBeAg- and HBV DNA-negative. In this study, HBsAg seropositivity rate in the neonates was found to be 20.5% (137/668). However, we could not determine the factors that could contribute to the rate of HBV transmission such as HBeAg status and HBV DNA levels in the mothers. In addition, we did not know the exact number of deliveries outside the hospital that could explain the insufficient immunoprophylaxis in some cases and the HBsAg positivity ratio in those neonates.

Turkey is located in an intermediate endemic area for HBV infection, but the prevalence of HBV infection varies across various regions of the country (3). It has been shown that HBsAg positivity rate among pregnant women ranged between 1.9% and 8.4% with an average of 4.4% (14). The HBsAg prevalence in pregnant women has been found to be 4.2-4-9% in the cities of the western and central regions of Turkey; it was 4.7-12.3% in the Eastern and South-eastern regions of Turkey (15). According to our results, HBsAg positivity rate was 4.2% (668/15585) in pregnant women and this result is in accordance with other prevalence rates in this region of Turkey. HBsAg seroprevalence rates of pregnant women among different cities are shown in Table 1.

Geographical differences may explain the variation in seroprevalence rates of HBsAg among pregnant women from different countries (38). HBsAg seropositivity rates among pregnant women from different countries are shown in Table 2.
The prevalence rate of HBsAg in the present study (4.2%) was lower than the rate reported by Lin et al. (15.5%) from Taiwan, by Madzime et al. (25%) from Zimbabwe, by Okoth et al. (9.3%) from Kenya, Rabiu et al. (6%) from Nigeria, by Zhang et al. (6.7%) from China, by Ramos et al. (6.1%) from Ethiopia, and by Murad et al. (10.8%) from Sudan (40,41,46,48,49,50,53). On the other hand, HBsAg prevalence rate in this study was high when compared to the rates reported from developed countries such as Greece, France, Italy, Denmark, Spain, and Germany (1,43,44,45,47,51).
The prevalence may also vary with ethnicity and immigration patterns. Lobstein et al. found that 0.48% of pregnant women were HBsAg carriers, in line with other data showing lower rates in the Eastern parts of Germany compared to the Western part (51). Furthermore, the prevalence was much lower in German-born women (0.2%) in comparison to Asian-born women (9.1%).

The present study has some limitations. First, we did not know the HBeAg positivity and HBV DNA level in the HBsAg-positive women, since they were the most important risk factors for  neonatal HBV transmission. Second, all pregnant women were screened for HBsAg positivity before delivery; all infants born to HBsAg-positive mother presumed vaccinated and received HBIG within 72 hours after birth. However, HBsAg positivity rate of 20.5% indicates that close follow-up and further improvement in universal implementation of immunoprophylaxis is also necessary.

Conclusion

All pregnant women should be tested for HBsAg during each pregnancy, preferable in the first trimester. They should be retested at the time of admission for delivery if HBsAg test result is not available or if the mother was at the risk for infection during pregnancy. The infants of HBsAg-positive mothers should receive vaccination and postexposure immunoprophylaxis to prevent perinatal transmission according to the WHO (World Health Organisation) and the CDC (Centers for Diseases Control and Prevention) recommendations. Although HBV vaccination has been the routine vaccination schedule for newborns in Turkey since 1998, screening of pregnant women in terms of HBV should be done. Our aim should be to control hepatitis B infection all over the country and to convert our intermediate endemic status into a low endemic region by continuing the HBV prenatal screening and hepatitis B immunization program in Turkey.