Hepatitis C is the most common chronic blood-borne illness in the United States. It affects about 3.5 million Americans. Mothers with hepatitis C transmit the virus to 4,000 newborn children every year, according to a report in the Annals of Internal Medicine.

If you are an expectant mother who has been exposed to the hepatitis C virus, you may have questions about your health and that of your baby.

The main risk factor for hepatitis C is injecting intravenous drugs, either currently or in the past. Healthcare workers stuck by needles and sex partners of people with hepatitis C are also at risk.

You have a slight risk of contracting hepatitis from tattoo needles and infected ink. The hepatitis C virus infects the liver. This liver infection can lead to nausea and jaundice, which shows up as yellow skin and eyes.

You may have no symptoms, though. And if you’re lucky, your body may clear the virus on its own, though this is not common.

If you have hepatitis C, you have a 3–5 percent chance of passing the infection on to your child, according to a study in the World Journal of Gastroenterology.

The same study found that the risk rises to nearly 20 percent if you also have untreated HIV. The good news is that hepatitis C doesn’t tend to have a negative effect on the course of the pregnancy or the birth weight of the baby.

You might wonder if a vaginal birth increases the risk of mother-to-child transmission of the virus. Based on the research, that doesn’t appear to be the case.

Researchers at the Oregon Health and Science University looked into 18 studies conducted between 1947 and 2012 on how delivery method relates to transmission of the virus. They could not find a clear connection between delivery method and the risk of transmitting the virus.

The researchers did not argue in favor of a caesarian delivery to avoid transmission. However, the researchers do point out that the studies were marred by small sample sizes and methodology drawbacks.

At this time, pregnant women with hepatitis C are not routinely recommended to have a cesarean delivery unless there are other risk factors present, such as HIV coinfection.

If you’re a mother with hepatitis C, it’s acceptable for you to breastfeed your child, according to the Centers for Disease Control and Prevention (CDC). Researchers do not believe the virus can be transmitted through breast milk.

Some studies did not find higher rates of hepatitis C in breastfed infants than in formula-fed babies. Talk to your doctor about your breastfeeding plans. If you have HIV and hepatitis C, this may be a consideration against breastfeeding.

It’s not certain that breastfeeding with cracked or bleeding nipples can spread the hepatitis C virus, according to the CDC.

However, hepatitis C can be transmitted through contact with infected blood, so the CDC advises against breastfeeding if you have cracked or bleeding nipples.

The organization suggests that mothers should discard their breast milk until nipples are completely healed.

If you believe you have hepatitis C, you may want to check with your doctor about getting a combination of blood tests.

The hepatitis C test is not routine for pregnant women. The test is normally only for people who fall in one of the risk categories. Even if you only used intravenous drugs one time, you are at risk and should get tested for hepatitis C.

You might also consider having the test if you have tattoos. If you test positive, the baby will also need to be tested after birth.

Between birth and 18 months, your baby will have antibodies for hepatitis C acquired from your body. This means an antibody test to determine if the virus is present won’t be reliable.

However, you can try a viral test when your child is between 3 and 18 months. The most reliable method for finding out if your child has hepatitis C is to have them tested after they turn 2 years old, using a test similar to the one used for adults.

The good news is that your child has a 40 percent chance of clearing the virus spontaneously by age 2, according to the American Liver Foundation. Some children even clear the virus on their own as late as 7 years old.