Herpes in the Pregnant Woman and the Newborn

HSV can cause serious complications in both the mother and the child. It should be noted, however, that each year about 1 million women infected with HSV-2 become pregnant, but complications occur in less than one in a thousand of them.

Effect of HSV on the Pregnant Woman

Pregnant women who are infected with either HSV-2 or HSV-1 genital herpes have a higher risk for miscarriage, premature labor, retarded fetal growth, or transmission of the HSV infection to the infant while in the uterus or at the time of delivery. One study also suggested a link between HSV-2 infection in mothers and the subsequent development of schizophrenia and other forms of psychoses in their adult offspring, although further study is needed. Recurrence in women previously infected with HSV is also common during pregnancy.

Approach to the Pregnant HSV Patient. The approach to a pregnant woman who has been infected by either HSV-1 or -2 in the genital area is usually determined by when the infection was acquired and the mother's condition around the time of delivery:

• If lesions are present at the time of birth, Cesarean section is usually recommended. An important 13-year study confirmed that this approach helps prevent transmission. In the study, the baby became infected in only 1.1% of Cesarean sections compared to 7.7% of vaginal deliveries. (Even a Cesarean section is no guarantee that the child will be HSV-free, and the newborn must still be tested.)
• If lesions erupt shortly before the baby is due then samples must be taken and sent to the laboratory. Samples are cultured to detect the virus at 3 - 5-day intervals prior to delivery to determine whether viral shedding is occurring. If no lesions are present and cultures indicate no viral shedding, a vaginal delivery can be performed and the newborn is examined and cultured after delivery.

Many doctors now recommend anti-viral medication for pregnant women who are infected with HSV-2. Recent studies indicate that acyclovir (Zovirax) or valacyclovir (Valtrex) can help reduce the recurrence of genital herpes and the need for Cesarean sections. Women begin to take the drug on a daily basis beginning in the 36th week of pregnancy (last trimester).

How HSV is Transmitted to Newborns

Although 25 - 30% of pregnant women in the U.S. and Europe have a history of HSV-2 infection, the risk of transmission to the newborn is low, occurring in between one in 3,500 - 20,000 births, depending on the population group.

The greatest danger to the baby is from an asymptomatic infection during a vaginal delivery in women who acquired the virus for the first time late in the pregnancy. In such cases, between 30 - 50% of the newborns become infected. Recurring herpes or a first infection that is acquired early in the pregnancy poses a much lower risk (less than 1%) to the infant.

The reasons for the higher risk with a late primary infection are:

• During a first infection, the virus is shed for longer periods, and more viral particles are excreted.
• An infection that first occurs in the late term does not allow the mother to develop antibodies that would help her baby fight off the infection at the time of delivery.

The risk for transmission also increases if infants with infected mothers are born prematurely, if there is invasive monitoring , or if instruments are required during vaginal delivery. Transmission can occur if the amniotic membrane of an infected woman ruptures prematurely, or as the infant passes through an infected birth canal. Very rarely, the virus is transmitted across the placenta, a form of the infection known as congenital herpes.

Unfortunately, only 5% of infected pregnant women have a history of symptoms, so in many cases HSV infection is not suspected, or symptoms are missed, at the time of delivery. Occasionally, lesions on the mother's buttocks may help indicate the presence of the virus.

Effects of HSV in the Newborn

HSV infection in a newborn is a very serious and even-life threatening condition if it goes undiagnosed and untreated. Fortunately, since the introduction of acyclovir the outlook for these children has significantly improved. In general, there are three categories of HSV in the newborn.

• Localized infection affects the skin, eyes, and mucous membranes. This condition is usually caused by HSV-1 and is temporary. However, in some cases, most often HSV-2 infections, later complications develop in between 5 - 10% of infants. If untreated, it may progress to very severe complications, notably disseminated or central nervous system infection.
• Disseminated disease can affect internal organs, such as the liver, the lungs, and the adrenal glands. It is fatal in up to 80% of newborns if left untreated, and those who survive are at high risk for complications, particularly in the eyes. If infants are treated, however, survival rates are close to 90%.
• Central nervous system infection can cause meningitis or encephalitis. This form is also highly fatal, and complications that affect learning and mental functions are common in surviving children.

Factors that Indicate a Higher Risk for Severe Complications

• Acute infection in the mother at delivery
• Prematurity
• Seizures in the infant
• Disseminated intravascular coagulopathy, a blood-clotting disorder that can occur in response to infection

Factors that Indicate a Lower Risk for Severe Complications

• Newborn infection caused by a recurring HSV-2 infection in the mother. (Mothers with such infections appear to pass along protective antibodies to the newborn. It should be noted that antibodies to HSV-1 do not appear to offer similar protection to the newborn.)
• Newborn infections that are confined to the skin and do not cause frequent outbreaks within the first 6 months.

Tests for the Newborn at Risk for HSV. Any newborn with an infected or high-risk mother should be tested and checked carefully for symptoms. (Experts are divided, however, over whether the high cost of testing mothers specifically for HSV before delivery, even in high-risk groups, is worth the benefit for such a small group of mothers and infants.)

• In the asymptomatic newborn delivered from an infected mother, cultures should be taken between 24 - 48 hours after birth. A culture taken right at the time of delivery may give a false indication of infection in the baby, simply because it can carry some of the mother's virus from the birth canal.
• Testing specimens for viral DNA using a test called polymerase chain reaction (PCR) is proving to be very important in newborns, particularly when central nervous system infection is suspected, since it eliminates the need for brain biopsies.
• While results are pending, the baby should be checked regularly for rashes and blisters, particularly in areas where the skin is broken, along with any signs of illness including fever, lethargy, respiratory distress, and poor feeding.

Symptoms of HSV in the Newborn. Although treatments have improved the outlook of infected newborns, there has been little change over the past 20 years in the time between the onset of symptoms and the initiation of treatments. Doctors and parents should be suspicious of any signs if there is any risk of infection to the newborn.

When symptoms occur in newborns, they usually become apparent within 5 - 17 days of life, but they may develop as early as 24 hours or as late as 34 days.

• An unstable temperature can be the first indication of the infection.
• About half of infected infants develop a rash. Lesions may range from raised spots to large isolated blisters. They can be anywhere on the skin or eyes or in the mouth.
• The other half of infected infants develop no lesions until later in the course of the infection. The absence of lesions, therefore, in high-risk infants should not be considered a guarantee that HSV has not been transmitted.
• Other symptoms to watch for include irritability, blotchy skin, discharge in the eyes, sensitivity to light, tearing, lethargy, jaundice, pallor, coughing, rapid breathing, a swollen abdomen (enlarged spleen), seizures, or tremors. Infection should be suspected in any infant with fever, irritability, lethargy, or poor feeding at 1 week of age.

Treatment of HSV in the Newborn. If HSV infection in a newborn infant is suspected, intravenous acyclovir treatment should begin immediately, since the potential dangers of the condition far outweigh any risks associated with the drug.

The following are recommendations for treating infants who have been infected or are at risk for infection:

• If disseminated or central nervous system infection has developed or is suspected, intravenous acyclovir treatment should continue for 21 days.
• If the infection is limited to the skin, eyes, or mouth and the infant is at low risk for more serious complications, treatment may be given for 10 - 14 days.

The American Academy of Pediatrics Committee on Infectious Diseases now recommends higher-than-standard doses to improve outcome in infants who have any of these infections. Investigators are studying whether giving long-term oral acyclovir to newborns following the initial infection will improve the outcome.