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Genital Herpes in Pregnancy

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PatientPlus articles are written by UK doctors and are based on research evidence, UK and European Guidelines. They are designed for health professionals to use, so you may find the language more technical than the condition leaflets.

See also: Antiviral Medication for Genital Herpes written for patients

This document should be read in conjunction with the main, separate Genital Herpes Simplex article.

Aetiology, epidemiology, transmission, presentation, complications and differential diagnosis of infection with herpes simplex virus (HSV) are dealt with in the main article and will not be discussed here. This article concentrates on the management issues specific to genital herpes infection during pregnancy.

Although rare in the UK, neonatal herpes is a severe condition and carries a high risk of morbidity and mortality. Neonatal herpes refers to infection acquired around the time of birth, whereas congenital herpes refers to infection acquired in utero and is extremely rare. The British Paediatric Surveillance Unit (BPSU) has not included neonatal herpes in recent reports but in the three years 2004-2006 there were 86 cases in the UK. HSV types 1 and 2 are equally causative agents.

New 2014 consensus guidelines bring together previous British Association for Sexual Health and HIV (BASHH) and Royal College of Obstetricians and Gynaecologists (RCOG) guidelines. Advice in this article is based on these UK guidelines.

When seeing a pregnant woman with genital herpes, important questions to ask are:

  • Is this a first episode (primary infection) or a recurrence? This may be difficult to distinguish and serology may be helpful, particularly in the third trimester where it will significantly alter management.
  • What trimester of pregnancy is the woman in?

A pregnant woman with suspected genital herpes should be under the care of a specialist in genitourinary medicine, and the obstetric team should always be informed. Women having midwifery-led care should be reviewed by an obstetrician.

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Management of a first episode

First-trimester and second-trimester presentation
There is no evidence that genital HSV infection occurring during early pregnancy is associated with an increased risk of spontaneous abortion or congenital abnormalities. Diagnosis and treatment are important to reduce symptoms, reduce viral shedding and to reduce the risk of recurrence or asymptomatic viral shedding around the time of delivery. The affected woman should be referred to a genitourinary medicine (GUM) clinic for confirmation of the diagnosis, treatment and screening for other sexually transmitted infections (STIs). If this cannot be arranged immediately, treatment should be commenced in primary care.

Aciclovir is not licensed for use in pregnancy but is not known to be harmful and should be first-line treatment. Manufacturers advise use only when benefit exceeds risk.[2] There is no evidence of an increased incidence of birth defects with either aciclovir or other standard antivirals.[3] However, there is more experience with aciclovir, hence it is considered first-line at this time.

The dose used is the same as for non-pregnant women, so the standard regime is aciclovir 400 mg three times a day for five days.

Symptomatic relief in the form of paracetamol and/or lidocaine 5% gel may be suggested.

Where a woman has acquired a first genital herpes infection in the first or second trimester, she should then take a suppressive dose of aciclovir 400 mg three times a day from 36 weeks of gestation. This reduces the risk of reactivation at term and the need for caesarean section.[4] Assuming there are no active lesions or symptoms at term, normal vaginal delivery should be planned unless there are other factors preventing this.

The same points regarding counselling and contact tracing, as listed in the separate Genital Herpes Simplex article, should also be covered as part of standard management.

Third-trimester presentation
Refer, diagnose and treat as for first trimester, then continue suppressive aciclovir therapy. In addition:

  • This scenario carries the greatest risk of neonatal infection. The quoted risk of neonatal herpes when the baby is delivered vaginally within six weeks following maternal primary infection is 41%.
  • A caesarean section is recommended for women who develop primary genital herpes in the third trimester, particularly within six weeks of delivery. Around 70% of neonatal infections result from asymptomatic HSV shedding during delivery.[5] 
  • Serology (HSV antibody testing) can be useful, to help distinguish primary and secondary infection and to type the virus. Up to 15% of women presenting for the first time will have serological evidence of prior infection. Because the risk in recurrent infection is so much lower and does not necessarily involve caesarean section, it is important to establish this where possible. Type-specific antibodies to the same type of virus isolated from active lesions would be suggestive of recurrent infection. However it is safest to assume a primary infection until proven otherwise as this result may take some time.
  • Inform the paediatrician.

Active HSV at the time of labour

  • Caesarean section is recommended.
  • Where vaginal delivery occurs:
    • Consider intravenous aciclovir for both mother and neonate.
    • Invasive procedures (fetal scalp monitoring, artificial rupture of membranes and instrumental delivery) should be avoided where possible as this is thought to increase risk of transmission.
    • The neonate should be treated with intravenous aciclovir and swabs should be taken from the eyes, skin, oropharynx and rectum.

Management of recurrent infection

  • Confirm the diagnosis.
  • There is no evidence that there is any increased risk of premature labour or intrauterine growth restriction for women seropositive for HSV.
  • If the woman has a history of recurrent genital herpes, she should be reassured that the risk of transmitting the infection to her baby is very small, even if she does have active lesions at delivery. The risk is approximately 0-3% for vaginal delivery.
  • Maternal antibodies will give some protection to the baby but neonatal infection can still occasionally occur.
  • Antiviral treatment is not usually indicated before 36 weeks of gestation. Although antivirals are believed to be safe in pregnancy, the risk:benefit balance changes for recurrent infection because episodes are usually shorter and self-limiting. Saline bathing and oral paracetamol are usually sufficient to control symptoms.
  • Consider suppressive treatment with aciclovir 400 mg three times daily from 36 weeks of gestation. (Three times a day as opposed to the usual twice daily suppressive dose is considered necessary because of the altered pharmacokinetics of the drug in late pregnancy.)
  • Aim for vaginal delivery in the absence of other obstetric contra-indications. Caesarean section is not routinely recommended for women with recurrent genital herpes lesions at the onset of labour.
  • If vaginal delivery did take place and there were HSV lesions present, the GP and community midwife should be informed so that they can monitor for signs of neonatal HSV.

Active lesions during labour

  • Caesarean section is not routinely recommended for women with recurrent genital herpes lesions at the onset of labour. The mode of delivery should be discussed with the woman and individualised according to the clinical circumstances and the woman's preferences after a full discussion of the risks and benefits of each option.
  • The increased risk associated with invasive procedures is considered negligible, so these may be used if need be.
  • The paediatrician should be informed and parents educated about hygiene and symptoms to look out for. No swabs or treatment are required unless the baby becomes unwell.

The main concern with maternal HSV infection during pregnancy is the risk of neonatal infection, as this can lead to severe neurological impairment and to death.

It is most likely to occur if the mother develops HSV for the first time during the final trimester. If this is the case, the baby is likely to be delivered before the development of protective maternal antibodies. HSV-2 neonatal infection has a worse prognosis than HSV-1. However, either type can lead to disseminated infection which may be fatal.[7]

Early diagnosis and prompt treatment are essential. Early recognition improves prognosis. Remember there may not be obvious symptoms in the mother and HSV can be transmitted through asymptomatic viral shedding, and indeed this is most often the case.[8]Consider the diagnosis in any infant in the first weeks of life who develops vesicles, seizures or sepsis.

Clinical features

  • These appear in the neonate two days to six weeks after delivery.
  • Many infected infants present with nonspecific signs and without mucocutaneous involvement.
  • There is rarely a history of maternal infection.
  • The infection may follow different clinical courses:
    • Localised infection - skin, eyes or mouth. This occurs in about 30% of cases. The vesicles are often at the presenting part or at sites of minor trauma, such as a scalp electrode.
    • Localised infections may progress to CNS or disseminated infection if not treated with intravenous aciclovir.
    • CNS infection, with or without skin, eye or mouth involvement, occurs in around 30% of infected infants and presents with lethargy, feeding difficulty and seizures.[7]
    • Disseminated infection which can cause jaundice, hepatosplenomegaly and disseminated intravascular coagulation.
  • Congenital HSV infection:
    • This is rare, but is more likely in mothers who have disseminated herpes infection. Intrauterine transmission is greatest during the first half of pregnancy. Most congenital herpes infections are due to HSV-2.
    • Congenital HSV can cause miscarriage, stillbirth, microcephaly, hydrocephalus, chorioretinitis and vesicular skin lesions.
    • If lesions appear within 48 hours of birth, congenital infection is the cause.
    • There is a high perinatal mortality (50%).

Treatment of a baby considered to be at risk of neonatal herpes

  • Prompt diagnosis and initiation of treatment are critical to neonatal outcome.[7] 
  • Take urine and stool cultures and swabs from the oropharynx, eyes and surface sites for viral culture and typing.
  • Intravenous aciclovir is given by many whilst waiting for the results and is the treatment of choice in confirmed infection.
  • The child should be isolated.
  • Breast-feeding is recommended unless the mother has herpetic lesions around the nipples. Aciclovir is excreted in breast milk but there is no evidence of harm.
  • Parents should be warned to report any early signs of infection such as poor feeding, lethargy, fever or any suspicious lesions.
  • All women should be asked at antenatal booking if they have ever had, or their partner has ever had, genital herpes.
  • Early notification of HSV infection to the obstetric and paediatric team enables appropriate management.
  • If the male partner has a history of genital HSV and the female is asymptomatic, the couple should be advised of the importance of not transmitting the infection in pregnancy. Specific advice includes:
    • Condom use throughout pregnancy may help to reduce the risk of HSV infection
    • Not to have sex during a recurrence, and in the last six weeks of pregnancy.
    • The risk of HSV-1 infection during orogenital contact should be discussed and contact avoided if there are oral lesions evident.
    • Avoid sexual promiscuity during pregnancy.
  • All women should have careful vulval inspection at the onset of labour to look for HSV lesions.
  • In about a quarter of cases, infection is acquired postnatally from somebody other than the mother. Staff or relatives with an active oral HSV lesion or herpetic whitlow, who come into contact with the neonate, should be advised about the risk of postnatal transmission and avoid direct contact between the lesion and the neonate.

Further reading & references

  1. Management of Genital Herpes in Pregnancy; British Association of Sexual Health and HIV and Royal College of Obstetricians and Gynaecologists (Oct 2014)
  2. British National Formulary; NICE Evidence Services (UK access only)
  3. Pasternak B, Hviid A; Use of acyclovir, valacyclovir, and famciclovir in the first trimester of pregnancy and the risk of birth defects. JAMA. 2010 Aug 25;304(8):859-66.
  4. Hollier LM, Wendel GD; Third trimester antiviral prophylaxis for preventing maternal genital herpes simplex virus (HSV) recurrences and neonatal infection. Cochrane Database Syst Rev. 2008 Jan 23;(1):CD004946.
  5. Straface G, Selmin A, Zanardo V, et al; Herpes simplex virus infection in pregnancy. Infect Dis Obstet Gynecol. 2012;2012:385697. Epub 2012 Apr 11.
  6. Anzivino E, Fioriti D, Mischitelli M, et al; Herpes simplex virus infection in pregnancy and in neonate: status of art of epidemiology, diagnosis, therapy and prevention. Virol J. 2009 Apr 6;6:40.
  7. Gardella C, Brown Z; Prevention of neonatal herpes. BJOG. 2011 Jan;118(2):187-92. doi: 10.1111/j.1471-0528.2010.02785.x.
  8. Robinson JL, Vaudry WL, Forgie SE, et al; Prevention, recognition and management of neonatal HSV infections. Expert Rev Anti Infect Ther. 2012 Jun;10(6):675-85. doi: 10.1586/eri.12.55.
  9. 2014 UK National Guideline for the Management of Anogenital Herpes; British Association for Sexual Health and HIV (2014)

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.

Original Author:
Dr Michelle Wright
Current Version:
Peer Reviewer:
Dr Helen Huins
Document ID:
2187 (v23)
Last Checked:
Next Review:
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