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.

This document should be read alongside the main, separate article Herpes Simplex Genital.

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.

If you see a pregnant woman with genital herpes, the most important questions to ask are:

  • Is this a first episode (primary infection) or a recurrence? See table below.
  • What trimester of pregnancy is the woman in?

Note: always inform the obstetric team. If it is the first episode, refer to genitourinary medicine (on the same day if possible).

Symptoms of primary infection vs recurrence in genital herpes

Primary infectionSecondary infection
Bilateral skin lesions (blisters, ulcers or fissures).Unilateral lesions.
Flu-like prodrome 5-7 days; tender inguinal lymph nodes; ± local oedema; tingling pain in genitals, buttocks or legs. 
Untreated episodes last ≤3 weeks.Shorter episodes ≤10 days.
Both may be asymptomatic; it may be hard to distinguish primary from secondary; secondary episodes tend to be milder and of shorter duration.

Management of first episode

First-trimester and second-trimester presentation[1][3] 

Genital HSV infection occurring during early pregnancy is associated with an increased risk of spontaneous abortion, intrauterine growth restriction, preterm labour and congenital herpes.[4][5] 

Refer to a genitourinary medicine clinic- same day referral if possible.

Confirm the diagnosis (take viral swabs if not seen on the same day by a genitourinary department). Diagnosis is by viral culture or PCR.

Screen for other sexually transmitted infections (STIs)

Manage symptomatically according to the patient's need. Follow the same procedure as that for primary infection in a non-pregnant person, as outlined in the main article.

Disseminated infection carries the greatest risk of intrauterine transmission and associated early pregnancy complications. It therefore requires hospital admission and treatment with intravenous aciclovir.

Use of antivirals in pregnancy:

  • Aciclovir has a good safety record in pregnancy (although not licensed for this use). It should be used with caution if at <20 weeks of gestation, but there is no evidence of teratogenicity.[6]
  • The dose in pregnancy is either 200 mg five times daily or 400 mg three times daily.[3]
  • Start within five days of onset of symptoms or if new lesions are still forming.
  • Valacyclovir and famiciclovir have also been used in early pregnancy and have not been associated with an increased risk of birth defects. Sample sizes, however, were small.[6][7]

Inform other people involved in the woman's antenatal care (midwife, obstetrician).

Aim for a vaginal delivery but consider offering Caesarean section.

Consider daily suppressive aciclovir from 36 weeks - to reduce the likelihood of HSV lesions and asymptomatic virus shedding at term, and so reducing the need for Caesarean section.[8] A dose of aciclovir 400 mg three times daily may be appropriate because of the altered pharmacokinetics of the drug in late pregnancy.[2]

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

Third-trimester presentation

Refer, diagnose and treat as for first trimester, and also:

  • This scenario carries the greatest risk of neonatal infection. The quoted risk of neonatal herpes, calculated from five studies, when the baby is delivered vaginally was 41%.[3]
  • Refer to an obstetrician.
  • Serology (HSV antibody testing) can be useful, to help distinguish primary and secondary infection and to type the virus. These may influence management decisions.
  • A Caesarean section is recommended for women who develop primary genital herpes within six weeks of delivery.[3]Around 70% of neonatal infections result from asymptomatic HSV shedding during delivery.[4] 
  • Caesarean section for the prevention of neonatal herpes has not been evaluated in randomised controlled trials and may not confer complete protection.
  • If the baby is delivered vaginally, avoid artificial rupture of membranes and invasive procedures (such as fetal scalp monitoring), which increase the risk of neonatal herpes. Consider intravenous aciclovir for the mother intrapartum and for the neonate.
  • Inform the paediatrician.

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Management of recurrent infection

  • Confirm the diagnosis.
  • Maternal antibodies will give some protection to the baby but neonatal infection can still occur.
  • Antiviral treatment is not usually indicated before 36 weeks.
  • Aim for vaginal delivery but avoid prolonged rupture of membranes.
  • Refer to an obstetrician for assessment. They may consider continuous aciclovir during the final four weeks of pregnancy, to reduce the risk of clinical recurrence at term.
  • Regular viral swabs and culture in late pregnancy do not predict viral shedding at term and are not recommended.
  • 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.[3] 
  • 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.
  • 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.

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. Neonatal herpes occurs in fewer than 2 per 100,000 live births.[10] It usually results from maternal viral shedding during delivery, which may be asymptomatic, but may also rarely be acquired in utero.

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, HSV1 infection can lead to disseminated infection which may be fatal.[11] 

Be aware of neonatal herpes:
  • Early diagnosis and prompt treatment are essential.
  • There may be no obvious symptoms in the mother - neonatal HSV can be transmitted from asymptomatic maternal HSV.

Clinical features

  • These appear in the neonate 2 to 28 days 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.[11]
    • Disseminated infection which can cause jaundice, hepatosplenomegaly and disseminated intravascular coagulation.[12]
  • 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.
    • 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.[11] 
  • 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.
  • If the male partner has a history of genital HSV and the female is asymptomatic, the couple should be advised not to have sex during a recurrence.
  • Avoid sexual promiscuity during pregnancy.
  • Condom use throughout pregnancy may help to reduce the risk of HSV infection.
  • The risk of HSV-1 infection during orogenital contact should be discussed and contact avoided if there are oral lesions evident.
  • All women should have careful vulval inspection at the onset of labour to look for HSV lesions.
  • Anyone with an active oral HSV lesion or herpetic whitlow, who comes into contact with the neonate, should be advised about the risk of postnatal transmission and avoid direct contact between the lesion and the neonate.
  • An HSV-2 PCR test with results available within two hours has recently been developed. This may help to identify women at risk of transmitting HSV to their babies, and to inform on appropriate modes of delivery.[11][13] 

Further reading & references

  1. Sexually Transmitted Infections in Primary Care; Royal College of General Practitioners Sex, Drugs and HIV Task Group and British Association for Sexual Health and HIV (2006)
  2. Management of genital herpes; British Association for Sexual Health and HIV (2007)
  3. Management of genital herpes in pregnancy, Royal College of Obstetricians and Gynaecologists (2007)
  4. 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.
  5. Kim ID, Chang HS, Hwang KJ; Herpes simplex virus 2 infection rate and necessity of screening during pregnancy: a clinical and seroepidemiologic study. Yonsei Med J. 2012 Mar;53(2):401-7. doi: 10.3349/ymj.2012.53.2.401.
  6. Li DK; Does antiviral medication for treating herpes simplex during pregnancy increase the risk of birth defects in offspring? Evid Based Med. 2011 Feb;16(1):30. Epub 2010 Nov 25.
  7. 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.
  8. 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.
  9. Anzivino E, Fioriti D, Mischitelli M, et al; Herpes simplex virus infection in pregnancy and in neonate: status of art of Virol J. 2009 Apr 6;6:40.
  10. Tookey P, Peckham CS; Neonatal herpes simplex virus infection in the British Isles. Paediatr Perinat Epidemiol. 1996 Oct;10(4):432-42.
  11. Gardella C, Brown Z; Prevention of neonatal herpes. BJOG. 2011 Jan;118(2):187-92. doi: 10.1111/j.1471-0528.2010.02785.x.
  12. Kimberlin DW, Whitley RJ; Neonatal herpes: what have we learned. Semin Pediatr Infect Dis. 2005 Jan;16(1):7-16.
  13. Gardella C, Huang ML, Wald A, et al; Rapid polymerase chain reaction assay to detect herpes simplex virus in the genital tract of women in labor. Obstet Gynecol. 2010 Jun;115(6):1209-16.

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 (v22)
Last Checked:
Next Review:
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