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(See also Hepatitis.)
Neonatal hepatitis B virus infection is usually acquired during delivery. It is usually asymptomatic but can cause chronic subclinical disease. Symptomatic infection causes jaundice, lethargy, failure to thrive, abdominal distention, and clay-colored stools. Diagnosis is by serology. Rarely, severe illness may cause acute liver failure requiring liver transplantation. Less severe illness is treated supportively. Active and passive immunization help prevent vertical transmission.
Of the recognized forms of primary viral hepatitis, only hepatitis B virus (HBV) is a major cause of neonatal hepatitis. Infection with other viruses (eg, cytomegalovirus, herpes simplex virus) may cause liver inflammation along with other manifestations.
Etiology
HBV infection occurs during delivery from an infected mother. Maternal acute hepatitis B occurring within 2 to 3 mo of delivery has about a 70% risk of transmission, but disease occurring during the 1st or 2nd trimester has only about a 5% risk. Risk of transmission is also high from asymptomatic hepatitis B surface antigen (HBsAg) carriers with the e antigen (HBe—see Hepatitis: Serology). Carriers without the e antigen or with anti-HBe are less likely to transmit the disease.
Mother–infant HBV transmission results primarily from maternofetal microtransfusions during labor or contact with infectious secretions in the birth canal. Transplacental transmission is unusual. Postpartum transmission occurs rarely through exposure to infectious maternal blood, saliva, stool, urine, or breast milk. Neonatal HBV infection may be an important viral reservoir in certain communities.
Symptoms and Signs
Most neonates with HBV infection are asymptomatic but develop chronic, subclinical hepatitis characterized by persistent HBsAg antigenemia and variably elevated transaminase activity. Many neonates born to women with acute hepatitis B during pregnancy are of low birth weight, regardless of whether they are infected.
Infrequently, infected neonates develop acute hepatitis B, which is usually mild and self-limited. They develop jaundice, lethargy, failure to thrive, abdominal distention, and clay-colored stools. Occasionally, severe infection with hepatomegaly, ascites, and hyperbilirubinemia (primarily conjugated bilirubin) occurs. Rarely, the disease is fulminant and even fatal. Fulminant disease occurs more often in neonates whose mothers are chronic carriers of hepatitis B.
Diagnosis
Diagnosis is by serologic testing (discussed in Hepatitis: Diagnosis).
Prognosis
Long-term prognosis is unknown, although HBsAg carriage early in life seems to increase the risk of subsequent liver disease (eg, chronic hepatitis, cirrhosis, hepatocellular carcinoma).
Treatment
Symptomatic care and adequate nutrition are needed. Neither corticosteroids nor hepatitis B immune globulin (HBIG) is valuable. No therapy prevents the development of chronic, subclinical hepatitis once infection is acquired. Because of the risk of developing significant disease, liver function should be monitored periodically.
Prevention
Pregnant women should be tested for HBsAg during an early prenatal visit. Failing that, they should be tested when admitted for delivery. Some women who are HBsAg-positive are treated with lamivudine during the 3rd trimester, which may prevent perinatal transmission of hepatitis B.
Neonates whose mothers are HBsAg-positive should be given 1 dose of HBIG 0.5mL IM within 12 h of birth. Recombinant hepatitis B virus vaccine should be given IM in a series of 3 doses. (Note: Doses vary among proprietary vaccines.) The first dose is given concurrently with HBIG but at a different site. The 2nd dose is given at 1 to 2 mo, and the 3rd dose is given 6 mo after the first. If the infant weighs < 2 kg, the first dose of vaccine may be less effective. Subsequent vaccine doses are given at age 30 days (or when discharged from the hospital), and then 2 other doses are given at 1 to 2 mo and 6 mo after the 30-day dose. Testing for HBsAg and anti-HBs at 9 to 15 mo is recommended.
Particularly where hepatitis B infection is highly endemic or HBsAg screening of mothers is impractical, all neonates should be vaccinated.
Separating a neonate from its HBsAg-positive mother is not recommended, and breastfeeding does not seem to increase the risk of postpartum HBV transmission, particularly if HBIG and hepatitis B virus vaccine have been given. However, if a mother has cracked nipples, abscesses, or other breast pathology, breastfeeding could potentially transmit HBV.
Last full review/revision October 2009 by Mary T. Caserta, MD
Content last modified October 2009
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