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Preventing mother-to-baby transmission

african mother and baby

Without the right treatment and care, a woman living with HIV can pass HIV on to her baby. This is called 'mother-to-child transmission' (MTCT) or ‘vertical transmission’. Taking anti-HIV drugs can dramatically reduce the risk of you passing on HIV to your baby.

Here's how mother-to-child transmission can occur:

  • During pregnancy – the foetus is infected with HIV through the mother's blood crossing the placenta.
  • During delivery – the baby is infected with HIV through the mother's cervical secretions or blood during childbirth.
  • During breastfeeding – the baby is infected with HIV through the mother's breast milk or blood during breastfeeding.

These factors increase the risk of passing HIV on to the baby:

But if you have the right treatment and care during your pregnancy, you have an undetectable viral load, and you don’t breastfeed, the chance of passing on HIV to your baby is very, very small – about one in 1,000.

How can vertical transmission be prevented?

There is a set of effective strategies that prevent vertical transmission from taking place. These are called PMTCT - prevention of mother-to-child transmission.

Many women living with HIV have given birth to HIV-negative children by taking these precautions:

  1. Taking anti-HIV drugs during pregnancy.
  2. Making a careful choice between caesarean section and vaginal delivery.
  3. Not breastfeeding.
  4. Giving the new baby an anti-HIV drug for a few weeks.

By doing these things, the chances of the baby having HIV become very low – under 1%. If you are on HIV treatment and have an undetectable viral load, the chances are lower still: 0.1%.

How does HIV treatment prevent vertical transmission?

Everyone with HIV is now recommended to start treatment at diagnosis whatever their CD4 count. This is because it has been found that waiting until your CD4 count drops to 350 (when people used to be advised to start) means you'll have a higher chance of becoming ill.

Outdated information you read might refer to pregnant women taking treatment during pregnancy and then stopping when they have given birth if their CD4 count is still high – this is not the case any more and you will keep taking your treatment.

There are two different ways in which anti-HIV drugs act to prevent MTCT:

  1. They reduce your viral load so your baby is exposed to less HIV while in the womb and during birth. The aim of HIV treatment is to get, and keep, your viral load to undetectable levels.
  2. Some anti-HIV drugs may cross the placenta and enter your baby’s body, preventing the virus from ever taking hold. Newborn babies are given a short course of anti-HIV drugs after they are born when their mother is known to be HIV positive.

You can reduce the risk of HIV transmission further by having a managed delivery. Your doctor will look at your viral load when you are 36 weeks pregnant and discuss options with you.

If you have an undetectable viral load, it is usually recommended that you have a vaginal delivery.

If your viral load is detectable, but very low (under 400), your doctor will look at your particular situation and discuss options with you - a planned Caesarean section will be considered.

If your viral load is above 400, it's recommended you have a planned Caesarean section.

What happens after my baby is born?

Your baby should start four weeks of anti-HIV drugs - known as infant Post-exposure prophylaxis (PEP) - in the first four hours after he or she is born. The baby will also have an HIV test in the first few hours. Further tests will be done in the following months to find out his or her HIV status.

It's important to remember that you should not breastfeed your baby if you have HIV as HIV is present in breast milk. Read more about what happens after the birth.

Next: Support while you are pregnant ››

‹‹ Back to: HIV treatment during pregnancy


The Information Standard: Certified member

This article was last reviewed on 27/6/2017 by Anna Peters

Date due for the next review: 27/6/2020

Content Author: S. Corkery (NAM)

Current Owner: Kerri Virani

More information:

Mother to child transmission, NAM Aidsmap

How likely is mother to child transmission?, NAM Aidsmap

What factors increase the chance of transmission from mother to baby?, NAM Aidsmap

Childbirth, NAM Aidsmap

HIV and having a baby, Greta Hughson, NAM Aidsmap, December 2015

Pregnancy and birth, (From HIV and Women booklet), NAM Aidsmap, 2014

HIV, pregnancy, and women’s health guide - TB co-infection, i-Base, December 2015

Viral load, Greta Hughson, NAM Aidsmap, May 2017

New British guidelines recommend treatment for everyone with HIV by Keith Alcorn, 24 June 2015, NAM

Townsend C et al. Low rates of mother-to-child transmission of HIV following effective pregnancy interventions in the United Kingdom and Ireland, 2000-2006. AIDS 22: 973-981, 2008

de Ruiter A et al. Guidelines for the management of HIV infection in pregnant women 2012 (updated May 2014) BHIVA, 2014

Lehman DA & Farquhar C Biological mechanisms of vertical immunodeficiency virus (HIV-1) transmission. Rev Med Virol 17: 381-403, 2007