Herpes and pregnancy
What is the risk of herpes in pregnancy?
Transmission of herpes simplex virus (HSV) infection from mother to baby can occur when the mother has active genital herpes lesions at the time of a vaginal birth. Herpes infection in the newborn baby is a serious condition and is associated with a risk of neonatal death. Most poor outcomes for babies occur where the mother is unaware she has had a herpes infection.
Symptoms of genital herpes
The first episode of infection can be associated with severe symptoms including painful genital ulcers, pain passing urine or inability to pass urine, fever and headache. However, in some people the infection can be mild or without any recognised symptoms.
People with recurring episodes of genital herpes tend to have milder symptoms and fewer lesions, or no symptoms at all. Before visible lesions are seen patients may experience itching or pain.
Mother to infant transmission
Women with a known history of genital herpes prior to pregnancy
Women who have had genital herpes lesions before becoming pregnant are not likely to pass the virus to their baby. However, transmission from mother to infant can occur if the mother has a recurrence at the time of birth; although, the risk is much lower than if the infection is occurring for the first time in pregnancy.
For this reason, preventive antiviral therapy with acyclovir is often recommended from 36 weeks for women with one or more recurrences during pregnancy. A caesarean birth is usually recommended for women who experience an outbreak of symptoms at the time of labour or rupture of membranes if close to term.
Women who have their first episode of herpes in pregnancy
Women who have their first outbreak of genital herpes near the time of birth are at risk of transmitting herpes to their newborn. Antiviral therapy is prescribed to the mother during pregnancy to reduce the length of time lesions are present and reduce the risk of complications in the mother. Caesarean birth may be recommended to avoid exposure of the baby to vaginal secretions which may contain the virus.
For women with no history of herpes, but who have an infected partner
Women with no history of genital herpes whose partner has a history of cold sores (generally HSV type 1) or genital herpes (generally HSV type 2) should avoid oral, vaginal and anal sex during the last 12 weeks of pregnancy. Condoms are recommended during the entire pregnancy.
The most common mode of transmission is via direct contact of the baby with infected vaginal fluid during birth. Infection in the baby prior to labour and birth is uncommon. The use of prophylactic antiviral medication has been shown to reduce the amount of virus present at the time of birth but does not completely eliminate the risk of transmission to the baby.
When is a caesarean birth recommended?
A caesarean birth should be offered as soon as possible to women in labour or with ruptured membranes at term who have active lesions on their vulva or cervix or symptoms which usually precede the development of lesions for that woman.
Caesarean birth is not recommended for women with recurrent genital HSV who have no evidence of active lesions at the time of birth or where non-genital lesions are present.
Care of the baby after birth
If there is concern regarding possible HSV exposure and infection, the baby should be monitored in hospital after birth.
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Last modified 28/5/2014.