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Cold sores in pregnancy

6-minute read

What is HSV?

If you or your partner has the virus that causes cold sores or genital herpes, you might be worried about what could happen when you're pregnant or have a new baby. Here's what you need to know about herpes simplex virus (HSV), and how to protect your baby from infection.

The herpes simplex virus is a very common virus carried by most people. Sometimes it causes cold sores or genital herpes.

Cold sores are blisters that form on the lips, around the mouth and nose. Genital herpes is blisters or sores around the genitals or anus. The blisters may form a crust after about 3 days. The sores go away by themselves within 2 weeks.

There are two main types of HSV:

  • HSV-1 causes mostly cold sores on the face and lips, and sometimes on the genitals
  • HSV-2 causes mostly genital herpes

Both viruses are transferred though contact of the skin, saliva or genitals, and the viruses stay in the body for life. The viruses do not always cause symptoms, so you can carry the virus without knowing it.

HSV-1 is very common, with about 8 in 10 Australians carrying it in their bloodstream. But only 1 in 3 people with the virus has ever had a cold sore. HSV-2 is less common.

It is common for women who have had cold sores in the past to experience an outbreak while pregnant.

What happens if I get cold sores or genital herpes during pregnancy?

Having the HSV virus does not affect your chance of becoming pregnant.

It is quite common for women to have a cold sore during their pregnancy, even if they haven’t had one for a long time. Cold sores should not affect your unborn baby. But they are infectious, so it’s a good idea to treat them.

Genital herpes should not affect the baby if you have your first outbreak or it comes back in the first 34 weeks. But it can be transferred to your baby during the birth, especially if it’s your first outbreak.

If you've ever had a cold sore or genital herpes and you become pregnant, or you develop these conditions during pregnancy, it's important to tell your doctor or midwife about it. Together you can make a plan for managing herpes during pregnancy and birth.

How is HSV treated during pregnancy or breastfeeding?

You can treat cold sores and genital herpes with:

  • aciclovir cream, available from a pharmacist without prescription
  • aciclovir or valaciclovir or famciclovir tablets, for which you need a prescription

These 'antiviral' drugs are known to be safe for pregnant and breastfeeding women and are effective most of the time.

How is genital herpes treated during pregnancy?

You should take acyclovir, valaciclovir or famciclovir tablets, as above.

If it's your first outbreak of genital herpes, your baby may be more at risk because you haven't had time to develop immune protection against the virus, which also helps protect the baby.

Some women experiencing an outbreak of genital herpes might be advised to have a caesarean. This would prevent the herpes virus passing from mother to baby during a vaginal birth. But most women in Australia with genital herpes do give birth safely to healthy babies vaginally.

It's often recommended that women who have ever had genital herpes take antiviral tablets prior to the birth, even if the herpes isn't active at the time.

Talk to your doctor or midwife about the best course of action for your situation.

How do I protect my baby from herpes?

Herpes can cause serious problems in a baby, such as infections to the eyes and throat, brain damage and even death.

A newborn baby can catch HSV-1 and HSV-2 from being kissed or touched by someone with cold sores, or during childbirth.

Fortunately, most babies born to women who carry the virus are not affected. But if you or your partner has a cold sore or genital herpes, talk to your doctor about keeping it under control during the pregnancy and after the birth. It is also important to treat these conditions aggressively while you are breastfeeding.

It's important to maintain strict hygiene habits when caring for a new baby if you, or anyone in close contact with the baby, have cold sores.

If you have cold sores, you should:

  • cover cold sores when you're around the baby
  • avoid kissing your baby until the sores are completely healed
  • avoid touching the cold sores then touching your baby
  • wash your hands thoroughly before touching your baby

What if I have a cold sore while breastfeeding?

If you have cold sores, it is safe to breastfeed your baby as long as the cold sores are not on the breast or nipple.

If they are, it may be wise to breastfeed from the unaffected nipple only until the lesions have cleared up. You would express and dispose of breastmilk from the affected nipple. Breastmilk itself doesn't contain the herpes virus but it can be contaminated through the skin lesions.

Talk to your doctor or midwife as soon as you notice any cold sores on your breast or nipple.

What happens if my baby gets herpes?

It is very important that herpes in a newborn is recognised and treated by a doctor in hospital immediately. Signs of herpes in a newborn include:

  • blisters on the skin
  • fever
  • irritability
  • tiredness
  • lack of appetite

If you think your baby might have the herpes virus, don't wait to see if they get better — seek medical help. Tell medical staff if you or your partner carry the herpes virus.

Resource and Support

If you are worried about your baby, see a doctor or midwife, or take them to the hospital.

FIND A HEALTH SERVICE — The Service Finder can help you find doctors, pharmacies, hospitals and other health services.

If you're not sure what to do or want more information, you call Pregnancy Birth Baby on 1800 882 436 to speak with a maternal child nurse.

Learn more here about the development and quality assurance of healthdirect content.

Last reviewed: May 2021


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Need more information?

Cold sores: self-care - MyDr.com.au

Cold sores are caused by the herpes simplex type 1 virus. Most people carry this virus in their bodies. Find out what products are available for cold sores.

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Cold sores | SA Health

Herpes simplex virus type 1 (HSV1) causes cold sores on the face or lips - it is spread by skin or mucous membrane contact with infected saliva

Read more on SA Health website

Cold sore infections - MyDr.com.au

Find the answers to common questions about cold sores, irritating blisters which are caused by the herpes simplex type 1 virus and can be triggered by stress, fatigue or exposure to sunlight.

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Cold sores - Better Health Channel

betterhealth.vic.gov.au

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Cold sores overview - MyDr.com.au

A cold sore is a skin infection that is caused by the herpes simplex virus (HSV). Cold sores usually occur on or around the lips or nose and are very common. They have nothing to do with colds.

Read more on myDr website

Cold sores: children & teens | Raising Children Network

Cold sores are quite common in older children and teenagers. Cold sores usually clear up by themselves, but see your GP if you’re concerned.

Read more on raisingchildren.net.au website

Mouth sores

This fact sheet explains some common mouth sores, their symptoms and treatment.

Read more on Queensland Health website

Genital Herpes | Family Planning NSW

Genital herpes is a common sexually transmitted infection (STI) caused by the herpes simplex virus (HSV). There are two types of herpes simplex virus.

Read more on Family Planning NSW website

Genital Herpes and Pregnancy

If you are pregnant and you get genital herpes, it is important to tell your midwife or obstetrician.

Read more on Queensland Health website

Genital herpes

Genital herpes is a sexually transmitted infection (STI) which shows as blisters or sores on the genitals. This is caused by the herpes simplex virus (HSV).

Read more on WA Health website

Call us and speak to a Maternal Child Health Nurse for personal advice and guidance.

Need further advice or guidance from our maternal child health nurses?

This information is for your general information and use only and is not intended to be used as medical advice and should not be used to diagnose, treat, cure or prevent any medical condition, nor should it be used for therapeutic purposes.

The information is not a substitute for independent professional advice and should not be used as an alternative to professional health care. If you have a particular medical problem, please consult a healthcare professional.

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