Hepatitis B and Pregnancy: What You Need to Know

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Hepatitis B virus (HBV) is a virus that causes infection and inflammation of the liver, leading to very serious, long-term illness. More than 2 billion people have been infected with HBV at some point. According to the World Health Organization (WHO), such infections caused approximately 820,000 deaths in 2019. In that same year, 296 million people were living with the virus HBV as a chronic infection. In the United States, the maternal prevalence of HBV (the percentage pregnant women testing positive for HBV infection) has been reported at 0.9 percent (9 out of 1,000 pregnant women), although the numbers vary between different populations of pregnant women within the US. In locations where the virus is endemic (present commonly among people), HBV infection has been reported in pregnant women at much higher rates, in some cases even approaching 10 percent or more.

In HBV endemic regions, the most important route by which HBV spreads is mother-to-child transmission, which is also called vertical transmission. Women at high risk for developing HBV infection include those who have had one or multiple sexual partners within the last six months who have tested positive for HBV, those who interact closely with people who are high risk (including physicians, nurses, or other health workers), and intravenous drug users.

HBV infection is diagnosed based analysis of blood samples. If there is suspicion that you may be infected with the virus, your blood would be tested for what’s called the HBV surface antibody (HBsAg) and also for what’s called the HBV core antibody (HBcAb). Additionally, your doctors may perform ultrasound examination of your liver and also a liver biopsy, meaning that a small amount of tissue would be taken from your liver for examination.

HBV causes infection and inflammation of the liver, leading to abdominal pain, vomiting, and jaundice (yellowing of the skin). A severe illness can develop rapidly and then resolve, but the virus can continue in a chronic state, meaning that it is present and producing symptoms that are more mild but go on, or wax and wane, over many years. Also, both a short severe disease (acute hepatitis B) and chronic disease can occur in the same person. People who suffer from chronic hepatitis B are carriers, meaning that they can easily infect other people who are exposed to their body fluids. Also, they can suffer long-term consequences in their livers, such as cirrhosis, liver cancer, or failure of the liver, all of which can be fatal. As with non-pregnant people, pregnant women who develop HBV infections can experience the acute illness and they also can enter the chronic carrier state, either directly after being infected, or following an acute HBV illness. Additionally, HBV infection in the mother carries a very real risk of transmitting the virus to the newborn during delivery, or during fetal life. Children who become infected at birth, or in the womb, have the highest risk of developing long-term HBV disease.

Appropriate medications and other treatments depend on the timing of your HBV exposure and the course of your illness. If you learn that you may have been infected with HBV within the past 12 hours, there is an emergency injection that you can receive, called immunoglobulin. It is an antibody similar to antibodies that you would be making against the virus had you been vaccinated earlier. The immunoglobulin can protect you for a short period of time, but when you get it, doctors also can give you the first dose of the HBV vaccine, which normally is administered as three injections, with one month between the first two doses, and then a longer period of time (generally 5-11 months) between the second and third dose. Alternatively, you can opt for a combined vaccine against both HBV and hepatitis A virus (HAV). This combined HAV/HAB vaccine requires more doses, and more time, however. Either you can have three injections, spread over a six-month period, or you can have three injections within one month, followed by a booster twelve months later.

HBV vaccine is a recombinant vaccine, meaning that it is made through genetic engineering techniques. In genetic engineering of the vaccine, genetic instructions for proteins that occur on the “coat” of the virus are used to create those proteins in bacteria, or other organisms, in a laboratory setting. Only those coat proteins, not any aspect of the virus that could enable infection and reproduction of new virus particles, are produced for use in the vaccine. After injection into your muscle, the proteins in the recombinant HBV vaccine provide target practice for immune system to recognize HBV, in the event that you are ever exposed to it. Since HBV vaccine is not a live vaccine, but instead consists of proteins made with genetic engineering, it is not thought to be dangerous for the baby.

If you develop a chronic HBV infection, your physician may recommend antiviral medication, of which there are several that are considered safe during pregnancy. While it is always possible that antiviral medicines will later be shown to produce some adverse effect in the baby, it’s very well established that infection with HBV in mothers is very bad for the baby, so fighting the virus is a top priority. Your physician also may give you injections of interferon alfa-2b, which works with your immune system to fight the virus. Interferon alfa-2b is thought to be safe during pregnancy (as long as it is not combined with a drug called ribavirin). As for nursing mothers, it is recommended that you avoid breast feeding when you are being treated with antiviral medications. Since there are no live virus components in HBV vaccine, it is not harmful to a nursing infant, so there is no conflict with getting the vaccine while you are breastfeeding.

For those who have become infected, treatment includes supportive measures such as rest, maintain your body fluids, and assuring that you receive good nutrition. For cases of HBV with a severely damaged liver, curative treatment involves transplantation of the liver, meaning that your diseased liver is replaced surgically with a liver, or part of a liver, from another person. Organ transplantation is not performed on pregnant women. If you require emergency liver transplantation and a suitable match is found for you, you would need to terminate you pregnancy in order to receive the new organ.

David Warmflash
Dr. David Warmflash is a science communicator and physician with a research background in astrobiology and space medicine. He has completed research fellowships at NASA Johnson Space Center, the University of Pennsylvania, and Brandeis University. Since 2002, he has been collaborating with The Planetary Society on experiments helping us to understand the effects of deep space radiation on life forms, and since 2011 has worked nearly full time in medical writing and science journalism. His focus area includes the emergence of new biotechnologies and their impact on biomedicine, public health, and society.

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