As an expectant parent eagerly awaiting the birth of your new baby, you are probably taking a number of steps to ensure your baby's health. One step many experts recommend is that you become informed about herpes simplex virus (HSV). Infection with this common virus is usually mild in adults; however, in infants, HSV can cause a rare, but serious, illness.

What is herpes simplex virus?

HSV can cause sores on the face and lips (facial herpes, for example "cold sores"), or sores on the genitals (genital herpes). HSV-1 is the usual cause of facial herpes, and HSV-2 is the usual cause of genital herpes. But either type of HSV can infect either part of the body. Either type can also infect a newborn baby.

How common is herpes simplex virus?

Figures for those infected with HSV-2 vary widely across different countries and between different populations. The prevalence of HSV-2 infection varies worldwide. Around 25% of American adults compared with around 4-14% of Europeans and Australians are infected with the virus. The proportion of genital herpes due to HSV-1 infection is high or increasing in many countries (e.g. England, Scotland, USA, Denmark, the Netherlands and Japan).

You can get genital herpes if you have sexual contact with a partner who is infected with HSV, or if a partner with HSV infection performs oral sex with you. Most people with HSV don't know they are infected because they have no symptoms, or their symptoms are too mild to notice.

How can herpes simplex spread to an infant?

• HSV is most often spread to an infant during birth if the virus is present in the birth canal during delivery.
• HSV can also be spread to the baby if he or she is kissed by someone who suffers from coldsores.
• In rare instances, HSV may be spread by touch, if someone touches an active cold sore and immediately touches the baby.

How can herpes harm a baby?

HSV can cause neonatal herpes, a rare but life-threatening disease. Neonatal herpes can cause skin, eye or mouth infections, damage to the central nervous system and other internal organs, mental retardation, or death. Medication may help prevent or reduce lasting damage if it is given early.

How many babies get neonatal herpes?

Although genital herpes is common, the risk of your baby being affected by neonatal herpes is low particularly if you contracted genital herpes before the third trimester of pregnancy. In the USA one in 1800-5000 live births are affected, in the UK one in 60 000, in Australia and France one in 10 000 and in the Netherlands one in 35 000 are affected. This means that the majority of women with genital herpes give birth to healthy babies.

Which babies are most at risk?

Babies are most at risk from neonatal herpes if the mother contracts genital HSV infection in the final trimester of pregnancy. This is because a newly infected mother has not yet produced sufficient antibodies against the virus, so there is virtually no natural protection for the baby before and during birth. In addition, newly acquired genital HSV infection is frequently active, so it is probable that the virus will be present in the birth canal during delivery.

What about pregnant women who have a history of genital herpes?

Women who acquire genital herpes before they become pregnant have a very low risk of transmitting HSV to their babies. This is because their immune system has already produced antibodies that are passed to the baby in the bloodstream through the placenta. Even if HSV is active in the birth canal during delivery, the antibodies help to protect the baby. In addition, if a mother knows she has genital herpes, her doctor can take steps to protect the baby.

Protecting the baby: women with genital herpes

If you are pregnant and you have genital herpes, you may be concerned about the risk of spreading the infection to your baby. Be reassured that the risk is extremely small especially if you have had herpes for some time. The following steps can help make the risk even smaller:

• Talk with your family doctor, obstetrician or midwife. Make sure he or she knows you have genital herpes.
• At the time of labour, check yourself for any symptoms in the genital area - sores, itching, tingling or tenderness. Your doctor will also examine you with a strong light to detect any signs of an outbreak.
• Your obstetrician should ideally discuss the choices for managing an active herpes outbreak at the time of delivery with you early in the pregnancy. The choices are to proceed with a vaginal delivery (avoiding routine use of instruments) or to have a Caesarean section. There is currently insufficient information to clearly support one option or the other; the risk of transmission with vaginal delivery is very low and must be weighed against the risk of Caesarean section to the mother.
• Ask your doctor not to break the bag of waters around the baby unless necessary. The bag of waters may help protect the baby for as long as possible against any virus in the birth canal.
• Ask your doctor not to use a foetal scalp monitor (scalp electrodes) during labour to monitor the baby's heart rate unless medically necessary. This instrument makes tiny punctures in the baby's scalp, which may allow HSV to enter. In most cases, an external monitor can be used instead.
• Ask that a vacuum or forceps are not used during delivery unless medically necessary. These instruments can also cause breaks in the baby's scalp, which may allow HSV to enter.
• After birth, watch the baby closely for about 4 weeks. Symptoms of neonatal herpes include blisters on the skin, fever, tiredness, irritability, or lack of appetite. While these symptoms can be initially mild, don't wait to see if your baby will get better. Take him or her to a physician at once. Be sure to tell the physician you have genital herpes.
• Think positively! The odds are strongly in favour of you having a healthy baby.

Protecting the baby: women who don't have genital herpes

The greatest risk of neonatal herpes is to babies whose mothers contract genital infection in the final trimester of pregnancy.

While this is a rare occurrence, it does happen, and can cause a serious, even life-threatening, illness for the baby. The best way you can protect your baby is to know the facts about HSV and how to protect yourself. The first step may be finding out whether you already carry the virus. If you have a partner who knows they have genital herpes and you don't know whether you have it, you need to discuss this with your doctor.

How can I get tested for genital HSV?

If you have genital symptoms, the most usual test is a virus culture which detects HSV from the affected genital site(s). To perform this test, your doctor must take a sample from the site of a herpes outbreak while it is active, preferably on the first day. Test results are available in around 7 days.

If you don't have symptoms, a blood test can tell whether you are infected with HSV-2, the type of HSV that usually infects the genital tract. (A blood test may also tell you whether you have HSV-1, but in many cases this simply means you have facial herpes).

The most accurate blood test is the Western blot, but this is largely a research tool. Other tests, such as immunoblot assays and POCKit^TM tests are more widely available. Some of these tests can only identify HSV-2 infection, others may detect HSV-1 and HSV-2, or not specify.

Ask your doctor about these tests as availability differs between countries and some tests are not as accurate as others.

How can I make sure I don't get genital HSV infection?

If you test negative for genital herpes, the following steps can help protect you from acquiring the infection during pregnancy:

• If your partner has genital herpes, abstain from sex during active outbreaks. Between outbreaks, he should use a condom from start to finish every time you have sexual contact, even if your partner has no symptoms (HSV can spread when no symptoms are present). Get your partner to talk with your doctor about using suppressive oral antiviral therapy for the duration of the pregnancy. Consider abstaining from sex during the last trimester.
• If you don't know whether your partner has genital herpes, you may wish to ask him to be tested. If your partner has genital or facial HSV infection, there is a chance that you may acquire it unless you take steps to prevent transmission.
• Do not let your partner perform oral sex with you if he has an active cold sore (facial herpes). This can give you genital herpes.

What if I contract genital HSV during late pregnancy?

If you experience genital symptoms, or believe you have been exposed to genital HSV, tell your obstetrician or midwife at once as infection during this time presents the greatest risk of transmission to your baby. However, be aware that herpes can lie dormant for several years. What appears to be a new infection may be an old one that is causing symptoms for the first time. Blood tests can tell whether your symptoms are the result of an old infection or if you have recently acquired genital HSV infection.

Talk with your doctor about the best way to protect your baby. When a pregnant women does contract genital HSV infection during the last trimester, some doctors will prescribe an antiviral medication. Some recommend a Caesarean delivery under these circumstances, even if no outbreak is present.

How can I protect the baby after birth?

A baby can get neonatal herpes in the first few weeks after birth. Such infections are almost always caused by a kiss from an adult who has a cold sore. To protect your baby, do not kiss him or her when you have a cold sore, and ask others not to. If you have a cold sore, wash your hands before touching the baby.

For partners of pregnant women

If your partner is pregnant, and she does not have genital HSV infection, you can help ensure that the baby remains safe from the infection. Find out whether you have genital HSV (see "How can I get tested?"). Remember, approximately 20% of sexually active adults do have genital HSV infection, and most do not have symptoms. If you find that you have the virus, follow these guidelines to protect your partner during the pregnancy:

• Use condoms from start to finish every time you have sexual contact, even if you have no symptoms. HSV can be spread even when no symptoms are present.
• If you have genital herpes outbreaks, abstain from sex until the outbreak has completely healed.
• Talk with your doctor about using antiviral medication to suppress outbreaks - this strategy may reduce the risk of transmission between outbreaks.
• Consider abstaining from intercourse during the last trimester. Explore alternatives such as touching, kissing, fantasising and massage.
• If you have active cold sores (usually caused by HSV-1), avoid performing oral sex with your partner.

• Your partner needs to tell her doctor if you have genital herpes so that all the issues can be discussed.

The best way to protect the baby from neonatal herpes is to prevent genital HSV during late pregnancy.