The Primary source of this article is the recommendation
published by Society for Maternal-Fetal
Medicine (SMFM) for screening, treatment and prevention of vertical
transmission of Hepatitis B in the January issue of American Journal of
Obstetrics and Gynecology by Dionne-Odom J. et al.
Nearly 240 million people worldwide are infected with
hepatitis B virus (HBV).
Specific to pregnancy, an estimated prevalence of 0.7-0.9%
for chronic hepatitis B infection among pregnant women in the United States has
been reported, with >25,000 infants at risk for chronic infection born
annually to these women.
While transmission through sexual intercourse and
intravenous drug abuse are the major risk factors for acquisition of hepatitis
B among adults in the United States,
perinatal transmission is responsible for up to 50% of HBV infection worldwide
Vertical transmission of HBV from infected mothers to their
fetuses or newborns, either in utero or peripartum, remains a major source of
perpetuating the reservoir of chronically infected individuals globally.
From a global public health perspective, chronic HBV
infection is the major source of hepatocellular carcinoma, leading to 50% of
cases worldwide and 80% in high-endemic areas for HBV.
In contrast to HBV acquisition in adulthood, which more
commonly leads to acute resolved infection and immunity, perinatal/neonatal HBV
is more likely to lead to chronic infection and its long-term disease risks.
Chronic hepatitis B infection will develop in up to 90% of exposed neonates
who do not receive appropriate immunoprophylaxis, in contrast to 10-25% of
infected children and only 5-10% of exposed immunocompetent adults.
Identification of pregnant women with chronic HBV infection
through universal screening has had a major impact in decreasing the risk of
neonatal infection. Recent data demonstrate that 95% of pregnant women are
currently screened prior to delivery for evidence of chronic HBV infection,
with rates of perinatal transmission decreasing significantly over the past 2
decades.
The recommendation of Society for Maternal-Fetal Medicine (SMFM) for
screening, treatment and prevention of vertical transmission are:
(1) Perform routine screening during pregnancy for HBV
infection with maternal HBsAg testing (grade 1A).
(2) Administer hepatitis B vaccine and HBV immunoglobulin
within 12 hours of birth to all newborns of HBsAg-positive mothers or those
with unknown or undocumented HBsAg status, regardless of whether maternal
antiviral therapy has been given during the pregnancy (grade 1A).
(3) In pregnant women with HBV infection, suggest HBV viral
load testing in the third trimester (grade 2B).
(4) In pregnant women with HBV infection and viral load
>6-8 log 10 copies/mL, HBV-targeted maternal antiviral therapy should be
considered for the purpose of decreasing the risk of intrauterine fetal
infection (grade 2B).
(5) In pregnant women with HBV infection who are candidates
for maternal antiviral therapy, tenofovir should be used as a first-line agent
(grade 2B).
(6) It is recommend that women with HBV infection be
encouraged to breast-feed as long as the infant receives immunoprophylaxis at
birth (HBV vaccination and hepatitis B immunoglobulin) (grade 1C).
(7) HBV infected
women who have an indication for genetic testing, invasive testing (eg
amniocentesis or chorionic villus sampling) may be offered–counseling should
include the fact that the risk for maternal-fetal transmission may increase
with HBV viral load >7 log 10 IU/mL (grade 2C).
(8) Cesarean delivery should not be performed for the sole
indication for reduction of vertical HBV transmission (grade 2C).
Issues to be considered in a pregnant woman diagnosed as
a chronic HBV carrier?
The majority of pregnant women diagnosed with chronic HBV
infection will be asymptomatic and identified through routine screening with
initial prenatal laboratory tests.
Identification of a pregnant woman as chronically HBV
infected also presents an important opportunity to counsel her regarding risks
to other family and household members. HBV is most easily transmitted via
sexual exposure or blood exposure but can also be transmitted through casual
shared use of household items such as eating utensils and toothbrushes, as well
as through personal contact such as kissing or routine childcare. Therefore,
family and household members should be evaluated for HBV status and referred
for vaccination if found to be uninfected and nonimmune.
The pregnant woman herself should also be assessed for
immunity status for hepatitis A and offered vaccination if not immune, since
coinfection with another viral hepatitis results in compounded morbidity.
To aid in counseling regarding risks and potential
management options as outlined above, baseline LFTs should also be drawn when a
positive HBsAg test result is obtained, along with a baseline quantitative
HBV-DNA level.
The woman should also be counseled regarding exposures to
potentially hepatotoxic medications, even those available over the counter,
such as acetaminophen, and to avoid the use of alcohol even when not pregnant.
Even if the maternal viral load is low and antiviral therapy
during pregnancy is not recommended, the newborn should still receive standard
prophylaxis with HBIG and HBV vaccine within 12 hours of birth, and ongoing
surveillance of the woman’s hepatic function after pregnancy is indicated.
References:
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