This information is also included in the booklet HIV and children in this series.

If you are HIV-positive and pregnant, or thinking about having a baby, it is important to know that you can pass on HIV to your baby during pregnancy, or during delivery, or by breastfeeding.
However, anti-HIV treatment can greatly reduce the risk of you passing on HIV infection to your baby. In addition, if the mother’s HIV viral load is detectable late in pregnancy, doctors will advise delivery through an operation (a caesarean birth) as this can further reduce the risk. Exclusive formula feeding is strongly recommended for all babies born to HIV-positive mothers in the UK.
A number of factors may make it more likely that you will pass on HIV to your baby. These include:

During pregnancy

• Being ill because of HIV.
• Having a high HIV viral load or a low CD4 cell count.
• If you used recreational drugs, particularly injected drugs.

During delivery

• Your waters breaking four or more hours before delivery.

• Having an untreated sexually transmitted infection when you give birth.

• If you have a vaginal delivery (rather than a caesarean delivery) when you have a detectable viral load.

• If you have a difficult delivery, for example forceps need to be used.

• If you have a premature baby.

After delivery

• If you breastfeed, you can pass HIV onto your baby through breast milk.

There are two different ways in which anti-HIV treatment can reduce the risk of you passing on HIV to your baby:

First, anti-HIV treatment reduces your viral load – the level of virus in your blood – so that your baby is exposed to less of the virus while in the womb and during childbirth. The aim of the HIV treatment is to get your viral load below 50 copies/ml. This is often referred to as an undetectable viral load.
Second, some anti-HIV drugs can also cross the placenta and enter your baby’s body where they can prevent the virus from ever taking hold. This is also why newborn babies are given a short course of anti-HIV drugs called PEP (Post- Exposure Prophylaxis) after they have been born, if their mother is HIV-positive.
Two drugs in particular have proven to be very effective at crossing the placenta and preventing a mother from passing on HIV to her baby. These are the nucleoside analogue (NRTI) AZT (Retrovir), and the non-nucleoside analogue (NNRTI) nevirapine (Viramune). The way in which these drugs are used (either AZT on its own, or AZT or nevirapine in combination with other anti-HIV drugs) will depend on how much damage HIV has done to your immune system, and at which point in your pregnancy HIV was diagnosed.

In the UK, and other countries where there is access to a full range of anti-HIV drugs for treatment, nevirapine should not be used by itself (in monotherapy) to prevent mother-to-baby transmission of HIV because resistance to the drug can easily develop if it is used in this way. Using this drug alone would limit your ability to benefit from it or related drugs in the future, should you need them to protect your own health.

In good health?

If you have a good CD4 cell count, low HIV viral load and are not ill because of HIV infection, the UK guidelines recommend that you start taking AZT in the final three months (third trimester) of your pregnancy. You will also need to take an intravenous injection of AZT during delivery and have a caesarean, rather than vaginal, delivery. Another option is to take a short course of combination antiretroviral therapy during the last few months of pregnancy in order to get your viral load down to below 50 copies/ml. You may then have the option of a planned vaginal delivery.

Your baby will receive treatment with AZT syrup for four weeks after it is born.

If you are in good health at the beginning of your pregnancy but become ill because of HIV later in your pregnancy and have to start taking antiretroviral therapy, then the aim should be to get your viral load undetectable. You should continue to take the anti-HIV treatment after your baby has been delivered.

Your baby will receive treatment with AZT syrup for four weeks after it is born.

High viral load?

If HIV has significantly damaged your immune system, or if you have a high viral load, then you are advised to take antiretroviral therapy, including two drugs from the nucleoside analogue class (NRTIs), ideally AZT and 3TC (lamivudine, Epivir), and either the non-nucleoside analogue (NNRTI) nevirapine or a protease inhibitor. The higher your viral load, the earlier during your pregnancy you will need to start taking treatment. If you still have a detectable viral load before giving birth, then you need to have a caesarean delivery, but if your viral load is below 50 copies/ml and there are no apparent problems with the pregnancy, you may be able to have a planned vaginal birth.

Your baby will receive treatment with AZT syrup for four weeks after it is born.

Already on treatment?

If you become pregnant whilst taking effective antiretroviral therapy, you are recommended to continue taking this treatment. You will need to have a special anomaly scan between weeks 18 - 20 of your pregnancy to check for any abnormalities in your baby’s development.

Your baby will receive treatment with antiretroviral syrup (usually AZT) for four weeks after it is born.

If you become pregnant whilst taking antiretroviral therapy and your anti-HIV drugs are not suppressing your viral load to undetectable, then you should have a resistance test to determine your best drug options and then change to these anti-HIV drugs. The aim should be to get your viral load undetectable by the time you deliver. You will need to have an anomaly scan between weeks 18 - 20.

Your baby will receive treatment with an antiretroviral syrup (to which your virus is not resistant) for four weeks after it is born.

Diagnosed late in pregnancy?

If you are diagnosed with HIV very late during pregnancy (32 weeks or later), then you will need to start taking antiretroviral therapy immediately.  A blood test will be used to determine any resistance you have to anti retroviral therapy. The most common drugs used in this situation are AZT, 3TC and nevirapine (Viramune), as these drugs are able to rapidly pass over the placenta into your baby’s body.

Your baby will usually receive treatment with the same combination of three drugs (AZT, 3TC, and nevirapine) as syrups for four weeks after it is born.

Diagnosed during delivery or afterwards?

If you are diagnosed HIV-positive during delivery, or just after, then you will usually be given a dose of AZT by injection and oral doses of 3TC and nevirapine. Your baby will also need to take a triple combination of anti-HIV drugs for four weeks.

Safety of treatment to prevent mother-to-baby transmission

There’s some evidence of a slightly increased risk of having a premature, or low birth-weight baby if the mother takes anti-HIV drugs during pregnancy, particularly if the mother takes a protease inhibitor. However this is a controversial issue and other evidence suggests that taking anti-HIV drugs does not cause premature delivery.

Preventing mother-to-baby transmission – delivery

The risk of your baby contracting HIV is reduced if you have a planned surgical delivery. This is called an ‘elective caesarean’ and is scheduled to take place for the 38th week of pregnancy. If your labour begins early, the surgical delivery will be performed sooner. Taking anti-HIV drugs during caesarean delivery reduces the risk of you passing on HIV to your baby to very low levels. However, as with all surgery, caesarean delivery carries some risks. These risks should be explained to you before you agree (give consent) to the procedure.

You are strongly recommended to have a caesarean delivery if you have a detectable viral load, or if the only anti-HIV drug you took during pregnancy was AZT.

If your viral load has been consistently below 50 copies/ml, then you may be able to have an actively managed vaginal birth. This means that your doctors and midwife will make sure that your labour doesn’t last too long and can take other steps to reduce the risk of you passing on HIV to your baby.

Preventing mother-to-baby transmission – breastfeeding

Breastfeeding carries a risk of you passing on HIV to your baby. The risk of transmission can be as high as one in eight, depending on your own state of health, how long breastfeeding continues, and whether the baby receives any food or water in addition to breast milk. In the UK and other countries where safe alternatives to breastfeeding are available, you are strongly recommended to feed your baby with formula milk from birth. Detailed advice and support on how to do this is available from medical services and you should ask for help if you have difficulty meeting the cost.