My cousin recently learned she had hepatitis B, and at the same time she found out she was pregnant. What effect will this have on the baby?

--L.K.

Approximately 300,000 new cases of hepatitis B are diagnosed in the United States each year. Acute hepatitis B complicates one to two of every 1,000 pregnancies, while five to 15 of every 1,000 pregnant women are chronic carriers.

Hepatitis B is transmitted through blood and bodily fluids -- blood transfusion, sexual contact, intravenous drug use are all ways of contracting hepatitis B. It can also be transmitted to a baby during delivery; 85-95 percent of infected infants contracted the virus while being born, and the remainder were infected by transplacental transfer during pregnancy, while breastfeeding, or through close contact with an infected person after birth.

Hepatitis B affects the liver. It can lead to liver failure and cirrhosis. If a pregnant woman has hepatitis B, her baby must be treated immediately after birth to prevent future liver damage. The combination of hepatitis B immunoglobulin and hepatitis B vaccine are started within 12 hours of birth. This regimen is about 90 percent effective in preventing the newborn from becoming infected. The Centers for Disease Control recommend that all newborns be vaccinated for hepatitis B through a series of three shots (one at birth; one at two to four months; one at six to 18 months); such universal vaccination may help eliminate problems with hepatitis B in the future.