Genital herpes is a viral infection that causes recurring sores or ulcers of the cervix, vagina, labia (folds of skin outside the vagina) and/or the surrounding skin.

The lesions can cause burning, itching or other irritation. Lesions last for several days. During this time, they "shed" the virus. A person who comes in contact with the herpes sores, during sex for example, is at risk for infection. Herpes virus may also be shed between episodes, even if no sores are present.

The frequency of recurrences varies from person to person. People with frequent symptomatic recurrences may take medicines to reduce the frequency of outbreaks.

If a pregnant woman happens to have an outbreak of genital herpes during labor and delivery, she can pass the herpes infection to the newborn. The risk is highest if delivery occurs during the initial or primary genital herpes outbreak. This is because:

• The number of virus particles present at the first outbreak is usually higher than those at repeat outbreaks.
• The mother's blood hasn't yet formed antibodies against the herpes virus. The antibodies only form after repeated outbreaks. (Antibodies cross the placenta and provide some protection against an infection being transmitted to the baby. The risk of infection is less, but not zero.)

Herpes infections in newborns are quite serious. Their immune system is not fully-formed. The infection may spread throughout the body and affect many organs and systems. There are several ways to minimize the risk of a woman transmitting the infection to her newborn.

• A Cesarean delivery is recommended if herpes infection is present when the water breaks, labor begins or a woman is ready to deliver. Ideally, it should occur before membranes have ruptured in labor.
• Tell your doctor if you have a history of past herpes infection. Your doctor will ask you about symptoms of herpes infection late in pregnancy and will do a careful examination for evidence of infection when you're ready to deliver. If symptoms or lesions are present, your doctor will likely recommend a cesarean delivery.
• To minimize the chances of a recurrence during delivery, many doctors and patients will choose to start anti-viral medicines late in pregnancy. Such medicines are generally safe and reduce the risk of a herpes recurrence.
• Pregnant women who don't have herpes but have a partner who has herpes should make sure the partner always wears a condom during sex. Safe sex practices are especially important if your partner has current symptoms or sores from a herpes infection. However, the virus continues to be shed between outbreaks. That's why a condom must always be used.

Managing herpes in pregnancy can be complicated. Your doctor or midwife can help answer questions and create a plan that minimizes risks to you and your baby. The most important thing you can do is to share your history of herpes infection with your health care professional.