Viral hepatitis is one of the most common and potentially serious infections that can occur in pregnant women. Six forms of viral hepatitis have now been identified, two of which, hepatitis A and hepatitis B, can be prevented effec-tively through vaccination.
Hepatitis A virus (HAV) is transmitted from person toperson primarily through fecal–oral contamination. Good hygiene and proper sanitation are important to prevent in-fection. However, vaccination is the most effective means of preventing transmission. The hepatitis A vaccine is available as both a single-antigen vaccine and as a combination vac-cine (containing both HAV and HBV antigens). Prior to vaccine availability, HAV accounted for one-third of cases of acute hepatitis in the United States. HAV infection does not progress to chronic infection. Diagnosis is confirmed by demonstration of anti-HAV IgM antibodies. HAV infection has no specific effects on pregnancy or the fetus. Vaccinationsafety during pregnancy has not been established, but the risk to the developing fetus is minimal because the vaccine contains inacti-vated purified viral proteins. Vaccination is recommended forindividuals who are intravenous (IV) drug users, who have certain medical disorders (chronic liver disease or receiving clotting factor concentrates), are employed in specific occu-pations (e.g., working in primate labs or research labs), and who travel to countries with endemic HAV infection. HAVimmune globulin is effective for both pre- and post-exposure pro-phylaxis and can be used during pregnancy.
Hepatitis B virus (HBV) infection is more serious thanHAV infection regardless of pregnancy status. HBV is transmitted by the parenteral route and through sexual contact. Ten to fifteen percent of infected adults develop chronic infection and, of those, some will become carriers. Testing for hepatitis B surface antigen (HBsAg) during preg-nancy is routine, as about half of pregnant women infected lack traditional high-risk factors. Vertical transmission of hepatitisoccurs to a significant but variable extent and is related to the presence or absence of maternal HBeAg: if the patient is positive for the “e” antigen, indicating a high viral load and active viral replication, her fetus has 70% to 90% risk of becoming infected; and most of such infants will become chronic carriers. The risk of fetal infection is higher if mater-nal infection occurs in the third trimester. Neonatal infectioncan also occur via breast milk.
Women who are HBsAg negative with risk factors for HBV infection should be offered vaccination during pregnancy.
Patients who have been exposed to HBV should be treated as soon as possible with hepatitis B immune glob-ulin (HBIG) and begin the vaccination series. All infants now receive vaccination against hepatitis B, with the ini-tial injection given between 2 days and 2 months of deliv-ery. Infants of mothers who are HBsAg positive should receivethe vaccine and HBIG within 12 hours of birth. Breastfeedingis not contraindicated in women who are chronic carriers if their infants have received both the vaccination and HBIG within 12 hours of delivery.
Hepatitis C virus (HCV) infection is a growing problemin the United States and has obstetric implications. Similar to HBV in transmission (sexual, parenteral, vertical), HCV infection is often asymptomatic. Diagnosis is made by serologic evidence of anti-HCV IgG. However, antibod-ies may not be detectable until up to 10 weeks after onset of clinical illness. PCR identification of HCV RNA may be a useful adjunct to diagnosis in early and chronic infection. The presence of anti-HCV antibody does not confer im-munity or prevent transmission of infection. Fifty percent of infected individuals go on to have chronic infection.
Screening for evidence of HCV infection is not rou-tine. However, the CDC recommends routine screening for cer-tain groups (Box 15.1). Vertical transmission occurs in 2%to 12% of cases, with the risk of fetal infection directly re-lated to the quantity of hepatitis C RNA virus in maternal blood. Vertical transmission is rare with an undetectable hepatitis C RNA viral load. Maternal co-infection with human immunodeficiency virus (HIV) is also associatedwith a higher risk of vertical transmission of HCV.
Other risk factors for fetal infection include prolonged rupture of membranes in labor and use of invasive fetal monitoring. Currently, there are no preventive measures known to reduce the risk of mother-to-child transmission; cesarean delivery has not been consistently associated with a decreased rate of vertical trans-mission and should be performed for usual obstetric indications in HCV-infected women. Breastfeeding is not contraindicatedin women with HCV. Newer therapies for HCV infection that clear detectable virus in the blood and normalize transaminase levels are promising in nonpregnant adults. Immune globulin does not contain antibodies to HCV and has no role in postexposure prophylaxis.
Hepatitis D virus (HDV) is an incomplete viral particlethat can only cause infection in the presence of HBV. Transmission of HDV is through the parenteral route; chronic infection can occur, resulting in severe disease in 70% to 80% of chronically infected individuals and mortal-ity rates as high as 25%. Vertical transmission has been docu-mented but is uncommon. Diagnosis is made by identificationof HDV antigen and anti-HDV IgM in acute disease; IgG antibodies develop, but are not protective. No vaccine is currently available. Measures to prevent HBV infection are effective in the prevention of HDV transmission.
Hepatitis E virus (HEV) infection is a waterbornedisease and is uncommon in the United States. The diseaseis typically self-limited, but has been associated with higher rates of fulminant hepatitis E and mortality in pregnant women, which can be as high as 20% after infection in the third tri-mester. Co-infection with HIV results in severe diseaseand high mortality in pregnancy. Diagnosis is made by serologic testing for HEV-specific antibodies in women with travel exposure. The risk of vertical transmission is very low, but cases have been reported. No vaccine is cur-rently available.