OVERVIEW

What is neonatal hepatitis B virus infection?

Hepatitis B virus, abbreviated as HBV, is commonly known as the hepatitis B virus.

Neonatal hepatitis B virus infection refers to an infectious disease caused by HBV infecting the fetus or newborn. The most common cause is maternal infection, which is then transmitted to the newborn. Currently, measures such as hepatitis B vaccination and hepatitis B immunoglobulin injection for newborns can reduce the likelihood of neonatal HBV infection.

Neonatal hepatitis B virus infection may present with hepatitis symptoms or remain as an asymptomatic carrier state. If the infant shows no symptoms, liver function can be closely monitored without treatment. For infants exhibiting hepatitis symptoms, supportive treatment is generally provided first, followed by antiviral therapy after the age of 1.

Is neonatal hepatitis B virus infection common?

China is a high-prevalence region for hepatitis B virus infection, with approximately 600 million people having been infected with HBV. Maternal infection is the most common cause of transmission to newborns. Therefore, in the past, neonatal hepatitis B virus infection was not uncommon in China.

However, with the nationwide implementation of prenatal hepatitis B screening, neonatal hepatitis B vaccination, and hepatitis B immunoglobulin injection as preventive measures, the incidence of neonatal HBV infection has significantly declined.

Active hepatitis B prevention measures for newborns can significantly reduce the risk of infection.

SYMPTOMS

What are the manifestations of neonatal hepatitis B virus infection?

Symptoms vary in severity.

• Asymptomatic:

Most infants show no symptoms at birth. Within 6 months after birth, they may only exhibit abnormal blood test results, mainly mild elevation of liver enzymes. Between 6–12 months after birth, hepatitis B virus-related antibodies may be detected, after which the infant transitions to a chronic carrier state. Liver function may remain normal for a long time, but the risk of developing cirrhosis or liver cancer in adulthood increases.

• Symptoms of acute hepatitis:

A small number of infants may develop symptoms of acute hepatitis, including severe jaundice (yellowing of the skin and whites of the eyes), hepatosplenomegaly, abdominal distension, feeding difficulties, failure to gain weight, and pale-colored stools.

• Symptoms of fulminant hepatitis:

Very few infants may develop fulminant hepatitis, presenting with liver failure symptoms such as hepatic encephalopathy and coagulation disorders. These include severe jaundice, confusion, skin bruising, bloody stools, vomiting blood, rapid breathing, and cyanosis (bluish lips). Fulminant hepatitis progresses rapidly, has a high mortality rate, and a very poor prognosis.

If the mother is a hepatitis B virus carrier, can fetal infection cause deformities?

Fetal hepatitis B virus infection mainly occurs in the third trimester of pregnancy. While the virus can cross the placenta and infect the fetus, it does not cause fetal deformities.

What complications can neonatal hepatitis B virus infection cause?

Most newborns infected with hepatitis B virus show no symptoms and develop no complications. However, a small number of infants with hepatitis symptoms may experience the following complications:

• Hematologic complications: Impaired blood clotting, leading to bleeding in various areas such as skin bruising, vomiting blood, or bloody stools. If intracranial hemorrhage occurs, seizures may develop.

• Neurological complications: In cases of liver failure, hepatic encephalopathy may occur, manifesting as confusion, lack of crying or movement, refusal to feed, or seizures.

What are the adverse outcomes of neonatal hepatitis B virus infection?

• Early adverse outcomes: During the initial infection, the hepatitis B virus remains latent. Only some infants develop hepatitis symptoms, and a small number of severe cases may progress to fulminant hepatitis or liver failure.

• Long-term adverse outcomes: Most infants later become chronic carriers of the virus without liver function impairment. However, neonatal hepatitis B virus infection may increase the risk of cirrhosis and liver cancer in adulthood.

CAUSES

How are newborns infected with the hepatitis B virus?

The hepatitis B virus (HBV) is a DNA virus, and carriers in the population are the main source of infection, primarily transmitted through bodily fluids. Newborns can contract HBV through three routes:

• Intrauterine infection: When the mother has active HBV infection, the virus can cross the placenta and invade the fetus, with a 5%–10% chance of causing congenital HBV infection. Intrauterine HBV infection mainly occurs in the late stages of pregnancy.

• Infection at birth: Newborns may contract the virus by coming into contact with and/or swallowing the mother's HBV-infected blood and secretions during delivery.

• Postnatal infection: After birth, newborns may become infected through breastfeeding by an HBV-positive mother or receiving non-standard blood transfusions. The likelihood of postnatal HBV infection is low, especially for newborns who undergo planned HBV immunization, as breastfeeding does not increase the risk of transmission.

If a pregnant mother has HBV infection, will the baby definitely be infected?

Not necessarily.

Additionally, effective preventive measures can significantly reduce the risk of transmission (with a protection rate of 95%–100%):

• Mothers with HBV infection should undergo relevant tests to assess the severity of the infection and take effective measures to suppress the virus.

• Newborns should receive the hepatitis B vaccine and hepatitis B immunoglobulin promptly after birth to effectively prevent infection.

If the father has HBV infection, can it be transmitted to the fetus?

Although some studies have detected HBV in sperm, there is no clinical evidence to support that infected sperm can transmit HBV to the fetus.

DIAGNOSIS

What tests are needed to diagnose neonatal hepatitis B virus infection?

• Hepatitis B serology panel: Blood is drawn for serological testing to assess hepatitis B virus-related antigens and antibodies, providing evidence of hepatitis B virus infection.
• Hepatitis B virus nucleic acid (HBV-DNA): Blood is drawn to examine viral replication in the body, providing evidence of hepatitis B virus infection and guiding subsequent treatment.
• Liver function tests: Blood is drawn to assess indicators such as transaminases, bilirubin, coagulation function, and albumin, determining whether liver function is impaired and guiding further treatment.
• Others: Tests such as liver ultrasound or other hepatotropic virus screenings may be performed to rule out other liver-damaging diseases.

TREATMENT

Which department should be consulted for neonatal hepatitis B virus infection?

Infectious diseases department, communicable diseases department, neonatology department.

How is neonatal hepatitis B virus infection treated?

• If there are no clinical symptoms, drug treatment is not required during the neonatal period, but regular follow-up examinations are necessary.

• If hepatitis symptoms are present, supportive treatment is needed, including liver cell protection, vitamin and amino acid supplementation, etc. Antiviral drugs are not recommended for infants under 1 year old.

• For severe infections, treatments such as interferon or glucocorticoids may be considered, but these have corresponding side effects and should be used under the guidance of a professional doctor.

Can neonatal hepatitis B virus infection be cured?

Most cases cannot be cured and require regular follow-up examinations and monitoring.

• Most newborns infected with hepatitis B virus will transition into an asymptomatic carrier state, with liver function remaining normal for a long time.
• A small number of newborns infected with hepatitis B virus may develop hepatitis symptoms, which can be alleviated with medication, but most will still transition into a carrier state after symptoms disappear.

About 10%–20% of infected children may naturally clear the hepatitis B virus during childhood or adulthood, leading to recovery.

What is the prognosis for children with neonatal hepatitis B virus infection?

After neonatal infection with hepatitis B virus, the virus remains in the body. During childhood or adulthood, it may develop into the following conditions:

• Long-term viral carrier state, with infectivity but no symptoms or abnormal liver function.

• Natural clearance of the virus, leading to recovery, with an occurrence rate of about 10%–20%.

• Development of chronic hepatitis B, which may progress to liver cirrhosis and/or liver cancer.

• Acute exacerbation of chronic hepatitis B virus infection, manifesting as recurrence of hepatitis symptoms during childhood or adulthood, with severe cases possibly leading to liver failure.

Is follow-up necessary after discharge for neonatal hepatitis B virus infection?

After discharge, regular follow-up examinations such as liver function tests and hepatitis B serology should be conducted to monitor the child's condition.

DIET & LIFESTYLE

Can mothers who are hepatitis B virus carriers or patients breastfeed?

If the mother is a hepatitis B virus carrier or a hepatitis B patient, the breast milk may contain the hepatitis B virus. In this case, can breastfeeding still be carried out?

As long as the newborn receives hepatitis B immunoglobulin (HBIG) and the hepatitis B vaccine after birth, breastfeeding is safe. The hepatitis B immunoglobulin and vaccine will protect the child from contracting the virus through breast milk.

If the child has not been vaccinated or received immunoglobulin, there is a risk of contracting the hepatitis B virus through breast milk. In this case, breastfeeding should be avoided, and formula milk can be used instead.

What precautions should be taken in daily life for newborns infected with hepatitis B virus?

Daily contact without bodily fluid exchange does not transmit the hepatitis B virus. However, avoid kissing the child mouth-to-mouth and sharing utensils or toothbrushes with the child.

Follow medical advice and schedule regular follow-ups for liver function tests, hepatitis B serology (HBsAg, anti-HBs, HBeAg, anti-HBe, anti-HBc), and hepatitis B virus DNA (HBV-DNA) testing.

PREVENTION

Can neonatal hepatitis B virus infection be prevented?

Yes, it can be prevented.

• Preconception: If a woman planning pregnancy is already infected with hepatitis B virus, she should receive active treatment to control viral replication.
• Pregnancy: Pregnant women should routinely undergo hepatitis B serologic testing to screen for infection. If the test results are positive, further HBV-DNA testing should be performed to assess viral load. If the viral load is too high, antiviral therapy can be administered during pregnancy to reduce the risk of transmission to the fetus and newborn.
• After birth: Newborns delivered by hepatitis B-infected mothers should receive hepatitis B immunoglobulin (HBIG) within 12 hours of birth, along with the hepatitis B vaccine according to the standard schedule (three doses at 1 day, 1 month, and 6 months of age). These measures can block mother-to-child transmission and prevent hepatitis B infection in the child.
• Post-intervention: After completing the immunization regimen, newborns should undergo hepatitis B antibody testing between 1 month after the final vaccine dose and 12 months of age to confirm the presence of protective antibodies.

How does immunoprophylaxis differ for preterm infants compared to full-term infants?

Preterm infants born to hepatitis B-infected mothers should receive HBIG within 12 hours of birth and an additional dose at 3–4 weeks of age (two doses total). They should also receive the hepatitis B vaccine according to the adjusted schedule (four doses at 1 day, 3–4 weeks, 2–3 months, and 6–7 months of age).

How to interpret hepatitis B antibody test results?

After completing immunoprophylaxis, newborns should undergo hepatitis B antibody testing between 1 month after the final vaccine dose and 12 months of age to confirm the presence of protective antibodies.

• If HBsAg is negative and HBsAb is positive, the child is uninfected and has developed protective antibodies.
• If HBsAg is negative and HBsAb is negative, the child is uninfected but lacks protective antibodies. A repeat three-dose hepatitis B vaccine series can be administered to stimulate antibody production.
• If HBsAg is positive, immunoprophylaxis has failed, and the child is infected with hepatitis B virus. Liver function should be evaluated to determine if hepatitis is present.