While neonatal herpes is rare, women who know they have genital herpes are often concerned about the possibility of transmitting the virus to their babies at birth.

Such concern is understandable because herpes can have devastating consequences for a newborn. However, the risk is extremely low, experts agree especially for women with known, long-standing infections.

Neonatal herpes is not a reportable disease in most states, so there are no hard statistics on the number of cases nationwide. However, most researchers estimate between 1,000 and 3,000 cases a year in the United States, out of a total of 4 million births. To put this in greater perspective, an estimated 20-25% of pregnant women have genital herpes, while less than 0.1% of babies contract an infection. "Neonatal herpes is a remarkably rare event", Says Zane Brown, MD, an expert on neonatal herpes and a member of the Department of Obstetrics and Gynecology at the University of Washington. "Compared to all the other possible risks in a pregnancy, the risk of neonatal herpes is extremely small."

Transmission rates are lowest for women who acquire herpes before pregnancy -- one study "Randolph, JAMA, 1993 - placing the risk at about 0.04% for such women who have no signs or symptoms of an outbreak at delivery. The chances of transmission are highest when a woman acquires genital herpes late in pregnancy.

Unfortunately, when infants do contract neonatal herpes, the results can be tragic. About half of infants who are treated with antiviral medication escape permanent damage. But others may suffer serious neurological damage, mental retardation or death. It's fear of these terrible consequences, rather than the level of risk, that makes neonatal herpes a concern.

If you are pregnant and you-have genital herpes, you will want to talk with your obstetrician or midwife about how to manage the infection and minimize the risk to your baby.

If you are a man with either oral or genital herpes and your partner is uninfected and pregnant, you can do even more to protect the baby. Since the highest risk to an infant comes when the mother contracts HSV-1 or 2 during pregnancy, you can take steps to ensure that you don't transmit herpes during this crucial time.

So learn what you need to know, and then relax and enjoy the excitement of the pregnancy.

How Neonatal Herpes Is Spread

In about 90% of cases, neonatal herpes is transmitted when an infant comes into contact with HSV- 1 or 2 in the birth canal during delivery. There is a high risk of transmission if the mother has an active outbreak, because the likelihood of viral shedding during an outbreak is high. There is also a small risk of transmission from asymptomatic shedding - this is when the virus reactivates without causing any symptoms - herpes symptoms.

Fortunately, babies of mothers with long-standing herpes infections have a natural protection against the virus. Herpes antibodies in the mother's blood cross the placenta to the fetus. These antibodies help protect the baby from acquiring infection during birth, even if there is some virus in the birth canal. That's the major reason that mothers with recurrent genital herpes rarely transmit herpes to their babies during delivery. Even women who acquire genital herpes during the first two trimesters of pregnancy are usually able to supply sufficient antibody to help protect the fetus.

Babies born prematurely may be at a slightly increased risk, however, even if the mother has a long-standing infection. This is because the transfer of maternal antibodies to the fetus begins at about 28 weeks of pregnancy and continues until birth. Babies delivered at term should be protected by antibodies -- but premature babies haven't gotten a full load.

Mothers who acquire genital herpes during the last trimester of pregnancy may also lack the time to make enough antibodies to send across the placenta. In addition, newly infected people - whether pregnant or not - have a higher rate of asymptomatic shedding for roughly a year following a primary episode. This higher rate of asymptomatic shedding, plus the lack of antibodies, create the greater risk for babies whose mothers are infected in the last trimester.

Mothers who acquire genital herpes in the last few weeks of pregnancy are at the highest risk of transmitting the virus to their infants. If the mother's infection is a true primary (she has no previous antibodies to either HSV-1 or HSV-2), and she seroconverts (becomes HSV positive) at the end of pregnancy, the risk of transmission can be as high as 50%, according to research. The risk is also high if she has prior infection with HSV-1, but not HSV-2. While acquisition of herpes in the last few weeks of pregnancy is rare, it may account for almost half of all cases of neonatal herpes. If a woman has primary herpes at any point in the pregnancy, there is also the possibility of the virus crossing the placenta and infecting the baby in the uterus. About 5% of cases of neonatal herpes are contracted this way.

Finally, about 5%-8% of babies who contract neonatal herpes are infected after birth, often when they are kissed - by an adult who has an active infection of oral herpes - cold sores.

Prevention: Mothers with recurrent genital herpes

If you are pregnant and know you have genital herpes, that fact alone gives you a significant advantage in protecting your baby - herpes facts. Studies show that most cases of neonatal herpes occur in babies whose mothers don't have any idea they are infected.

This statistic is due, in part, simply to the large number of people who have genital herpes and don't know it. But it's also due to the lack of precautions taken by women and doctors who don't realize that neonatal herpes is a possibility.

When neither the mother nor her provider knows she's infected, neither are alert for lesions at delivery or likely to notice mild or atypical symptoms of an outbreak. On the other hand, when a woman and her provider do know there's a risk, the provider can examine her visually with a strong light at the onset of labor. This is currently the best way to detect herpes lesions. The provider can also take a viral culture at delivery to aid in diagnosis, should the baby become sick later.

In addition, findings presented at the 1994 International Herpes Management Forum suggest that women who are educated about genital herpes can often identify lesions even more accurately than their doctors. Women can also identify prodromal symptoms. Women can increase the likelihood of a doctor's spotting mild or atypical outbreaks by pointing to the site where lesions usually occur.

While some women may feel awkward discussing herpes in the delivery room, the best course is to think of the baby's well-being and be frank, doctors say. It can be hard with three or four people there you've never seen before, but the important thing is to forget the stigma that unfortunately exists and just come out with it.

Lesion at delivery

If a woman does have a lesion or prodromal symptoms at delivery, the safest practice is a cesarean delivery to prevent the baby from coming into contact with active virus. What are the chances that a woman with recurrent herpes will have a lesion at delivery? Many women find that their outbreaks tend to increase as the pregnancy progresses, probably because of the immune suppression that takes place to prevent the mother's body from rejecting the fetus. Between 10% and 14% of women with genital herpes have an active lesion at delivery. The odds are higher for women who acquire herpes during pregnancy, and lower for women who have had herpes for more than six years.

Fetal scalp monitor: trouble or no?

One practice that may contribute to transmission of neonatal herpes is the use of a fetal scalp monitor (scalp electrodes) during childbirth. This instrument, which is used to monitor the baby's heartbeat, actually makes tiny punctures in the baby's scalp. Several studies have shown that those breaks in the skin may serve as portals of entry for herpes virus.

While the risk from the scalp monitor may be quite small, a cautious approach would be for a pregnant woman to ask that it not be used unless there is a compelling medical reason. An alternative is the external monitor, which tracks the baby's heartbeat through the mother's abdomen.

No lesion at delivery

If a woman doesn't have herpes lesions at the time of delivery, the standard of care recommended by the American College of Obstetrics and Gynecology (ACOG) is vaginal delivery. This does expose the baby to a very small risk of infection from possible asymptomatic shedding.

Prevention: Men with Genital Herpes

If you are a man and know you have genital herpes, you have a key role in protecting your unborn child from neonatal herpes. As discussed above, the baby is at the greatest risk when the mother acquires an infection during the last trimester of pregnancy.

This happens most often when neither parent realizes that there is a risk of transmission. So, the first step is for both you and your pregnant partner to find out for sure who is infected and who is not.

At the moment, HSV screening for all pregnant women nationwide is not practical. An accurate, type-specific serology (blood test) is not available in most commercial labs. However, one accurate serology -- the Western blot -- is available from the University of Washington at Seattle (206-548-6066). To find out how you or your partner can get a Western blot, ask your doctor to call the lab at the number listed here. Your partner may also wish to have a Western blot late in pregnancy, since two-thirds of women who acquire genital herpes in pregnancy never have symptoms -- meaning neither they nor their doctors know there is a risk for neonatal herpes.

If your partner finds that she is infected, she can talk with her obstetrician or midwife about how to minimize the risk at delivery. If you are infected and she is not, you can take precautions to prevent transmission during pregnancy.

Such precautions include - abstaining from sex when you have active outbreaks, using condoms for intercourse between outbreaks, and possibly abstaining from intercourse during the last trimester

If you have oral HSV-1, approximately 50%-80% of adults do, avoid oral sex when you have an active outbreak - cold sores. HSV-1 can spread to your partner's genital area and give her genital herpes. Some 20%-30% of neonatal herpes cases are caused by HSV-1, so this is a real danger.

While these precautions may mean changing your sexual practices for a few months, you can have the reassurance of knowing that you have prevented the single most dangerous risk of neonatal herpes to your baby.

Women who get herpes during pregnancy

Many women who have their first outbreak of genital herpes during pregnancy do not actually have a new infection - instead, the outbreak is the first symptomatic recurrence of a longstanding infection. If you experience your first outbreak late in pregnancy, get a Western blot serology, if at all possible. (See above, for how to get a Western blot.) If performed promptly, a Western blot can tell you whether the outbreak is a true primary (a new infection in a person with no previous antibodies to either HSV-1 or HSV-2), or a non-primary first episode (an infection of HSV-2 in a person with previous antibodies to (HSV-1), or a recurrence. Ask your doctor to let the lab know how many weeks pregnant you are.

A woman who has a primary episode in the last trimester, especially in the last four to six weeks, may be treated to reduce the viral load. Some experts might also recommend a cesarean delivery under these circumstances. If a woman becomes infected during the third trimester, even if she's treated, there's a higher risk for shedding at delivery. In this rare situation, a C-section may really be of help, even if she has no symptoms or visible lesions. However, ACOG recommends a vaginal delivery if no lesions are present.

Unfortunately, most women who acquire herpes during the last trimester are unaware of their infection. Thus, neither they nor their babies receive the attention, treatment, and care they would receive if the infection were known.

Experimental approaches

Valtrex or Acyclovir are occasionally prescribed for pregnant women who suffer from extremely frequent outbreaks, or those who acquire genital herpes during pregnancy. The use of acyclovir or Valtrex (valacyclovir) during pregnancy is not recommended by ACOG or approved for use during pregnancy by the Food and Drug Administration. Ongoing studies may clarify the role of antiviral medications.

After the Baby Is Born

The possibility of acquiring neonatal herpes after birth is a risk for every baby. When such infections do occur, the cause is almost always HSV-1, which spreads from an adult who has an oral infection - cold sore. In many cases, the adult is a family member who has no idea that the minor irritation of the cold sore can be dangerous to an infant with an immature immune system.

To help protect your baby, educate family members about the danger of cold sores. Don't kiss your baby when you have an active sore, and also ask friends and relatives not to do so. In addition, if you have an outbreak of genital herpes, be sure to wash your hands before touching the baby. No extreme precautions are necessary. There is no risk in holding the baby, breast feeding, or having the baby in bed with you.

If the baby's mother has genital herpes, it is worth keeping a close eye on the baby for several weeks after birth, just to make sure no infection develops. Symptoms usually start in the first 14 days of life and may develop any time in the first month.

Some herpes symptoms, such as blisters on the body, are indicative of herpes. Others, such as lethargy, poor feeding, irritability, or fever could stem from any of a number of minor problems. The important point is that if anything seems wrong with your baby, take him or her to your pediatrician immediately, instead of waiting to see whether the situation will improve. If the baby doesn't behave well, if it's feverish, irritable, has blisters - don't delay.

Make sure you tell your pediatrician specifically if either parent has a history of genital herpes. Don't assume something you've told your obstetrician gets conveyed to your pediatrician.