Introduction {#sec1-1} ============ In India, the incidence of chronic hepatitis B infection is estimated to be around 7.8%.\[[@ref1]\] Prevalence is expected to be lower in the general population, as the disease occurs more often in people at risk.\[[@ref2][@ref3]\] In most cases, this infection is acquired from vertical transmission from an infected mother to her child.\[[@ref4]\] Other modes of transmission are transfusion of infected blood, intravenous drug use, and sharing of contaminated sharps.\[[@ref5][@ref6][@ref7][@ref8]\] The WHO estimated that about 350 million people are chronically infected with hepatitis B virus (HBV), a major cause of liver cirrhosis and hepatocellular carcinoma. While there are many cases of acute hepatitis B infection, chronic infection is present in 8% of cases only, with 3.5% showing clinical symptoms and about 1% eventually developing liver cirrhosis.\[[@ref9]\] As mentioned above, most HBV infections occur during childhood, and about 90% of individuals who are infected as children will develop a chronic infection.\[[@ref9]\] However, in some countries, the prevalence of HBV infection in pregnant women is as high as 8-12%,\[[@ref10][@ref11][@ref12][@ref13]\] and in regions where hepatitis B immunization is not available, the prevalence in children is higher than 0.2%.\[[@ref14]\] Mother to child transmission (MTCT) has become a serious public health problem worldwide with a mortality rate of 10-30% in cases of chronic infection.\[[@ref15]\] The presence of hepatitis B surface antigen (HBsAg) in the peripheral blood is indicative of chronic HBV infection. The transmission of HBV infection to infants from chronically HBV-infected mothers is related to the amount of maternal HBV DNA, with HBV DNA levels of over 10^4^ copies per ml showing a high rate of transmission. In case of high viral load, it is hypothesized that there is a greater rate of MTCT, with the infant acquiring more of the circulating HBsAg.\[[@ref16]\] The risk of MTCT is inversely related to the age of the child. A retrospective study reported a risk of 0.9% among infants born to mothers with low viremia (HBV DNA \<10^5^ copies/ml) to 20.9% among infants born to mothers with high viremia (HBV DNA \>10^5^ copies/ml).\[[@ref17]\] It is estimated that there are 350 million people chronically infected with HBV worldwide, with 130-170 million carriers in Africa.\[[@ref18]\] In Saudi Arabia, the prevalence of HBV is very high, and estimated to be 9.2%.\[[@ref19]\] A cohort study in Saudi Arabia reported that the overall rate of MTCT was 3.9%, and it ranged from 3.4% among HBeAg-positive mothers to 8.8% among HBeAg-negative mothers, with a trend of high risk in the neonates born to HBeAg-negative mothers.\[[@ref19]\] There are no data on the incidence of chronic hepatitis B infection in pregnant women in Kuwait. There are some regional data on the prevalence of HBsAg in children younger than 15 years, with a prevalence of 7.2% in Iraq, 6.7% in Palestine, and 5.5% in Saudi Arabia.\[[@ref20]\] HBV-infected pregnant women, whether HBsAg-positive or HBsAg-negative, represent a unique population, in which their newborns are at risk of contracting this disease. We studied the incidence of HBsAg-positive pregnant women among infants born in our hospital over a period of 5 years and tried to elucidate any predisposing factors. Subjects and Methods {#sec1-2} ==================== This is a retrospective descriptive study on data obtained from the database of the Gastroenterology Department of the Ahmadi Hospital in Kuwait City. The study was approved by the Ministry of Health and by the Ethical Review Board of the Ahmadi Hospital, and was conducted according to the principles of the Declaration of Helsinki, as revised in 2000. Informed consent from the patients was waived by the board, as no invasive procedures were done on the patients. The medical records of all pregnant women admitted to our hospital for delivery were reviewed from January 2003 to December 2007. The data of pregnant women who were admitted for delivery were collected by a trained research assistant. These data were entered into the SPSS version 13 for Windows. The required data were entered using a standardized questionnaire. Data obtained included age, gravidity, parity, gestational age at delivery, and neonatal gender. HBsAg testing was performed on umbilical cord blood by enzyme-linked immunosorbent assay. Infants born to HBsAg-positive mothers were further tested for HBeAg by enzyme-linked immunosorbent assay and DNA was extracted from cord blood of all these infants to detect HBeAg by polymerase chain reaction. We calculated the relative risk for MTCT of HBV infection by using Stata version 8. Chi-square analysis was used to compare continuous and discrete variables between groups. *P* \< 0.05 was considered statistically significant. Results {#sec1-3} ======= During the study period, 23,736 pregnant women were admitted to Ahmadi Hospital for delivery. Among these, 2,372 had a singleton birth. A total of 971 women were HBsAg-positive, accounting for 9.6% of the total number of deliveries. The incidence of HBsAg positivity among the total number of pregnant women was 9.2%. Only 25% of HBsAg-positive women were seropositive for HBeAg; among the remaining 75%, none of them showed HBeAg in the umbilical cord. Of the 971 HBsAg-positive pregnant women, 830 (84.3%) delivered singleton neonates. [Table 1](#T1){ref-type="table"} summarizes the basic characteristics of HBsAg-positive women in this study. ###### General characteristics of hepatitis B surface antigen-positive pregnant women  HBsAg-positive women were further subdivided into 5 groups based on their age: 15-19 years, 20-24 years, 25-29 years, 30-34 years, and 35-44 years. There was no significant difference between these 5 groups in the rate of MTCT (7.9%, 7.3%, 9.7%, 8.6%, and 6.7%, respectively). No significant difference was noted between the age groups in the MTCT rate (*P* = 0.12). When the parity was considered, a significant difference in the MTCT rate was noted, with parity ranging from 0-1 showing 8.9% MTCT, and 2-5 showing 12.5% MTCT (*P* = 0.03) [Table 2](#T2){ref-type="table"}. ###### Categorization of hepatitis B surface antigen-positive pregnant women by age and parity  Multiple logistic regression was used to assess the possible effect of parity and age on MTCT. Infants born to mothers who were primigravida had a significantly higher MTCT rate (11.1%) than did those born to multigravida (3.8%) mothers (*P* = 0.002) [Table 3](#T3){ref-type="table"}. ###### Variables that affect mother-to-child transmission  When parity and age were both used in the logistic regression model, it was found that parity was significant, with parity ranging from 2-5 showing a lower rate of MTCT (4.5%) compared with parity ranging from 0-1 (8.9%) (*P* = 0.05) [Table 3](#T3){ref-type="table"}. In addition, a multivariate logistic regression showed that multiparity was the strongest risk factor for MTCT compared with primiparity (*P* = 0.003) [Table 3](#T3){ref-type="table"}. Discussion {#sec1-4} ========== HBsAg-positive mothers are at a higher risk of MTCT, with an incidence of 9.2% in our study. The major mode of transmission of HBV in our study was from the mother to the newborn. MTCT has become a major problem worldwide, with a mortality rate of 10-30% among cases of chronic hepatitis B infection. There are no data on the incidence of chronic hepatitis B infection in pregnant women in Kuwait. There are some regional data on the prevalence of HBsAg in children younger than 15 years, with a prevalence of 7.2% in Iraq, 6.7% in Palestine, and 5.5% in Saudi Arabia.\[[@ref20]\] In our study, the incidence of HBsAg positivity among the total number of pregnant women was 9.2%, which is lower than the incidence reported for the Iraqi population. The rate of MTCT was 7.9% in our study, and lower than the incidence of 22% reported in Iraq, and 28.8% reported in Palestine.\[[@ref20]\] This suggests that HBV screening programs should be implemented in Kuwait and other regions where these data may not be readily available. It has been shown that MTCT can be prevented by effective vaccination, and vaccination is very important in Kuwait, a region with a high rate of chronic HBV infection and vaccination coverage. In our study, 25% of HBs