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Preventing mother-to-baby transmission of HIV - treatment
Taking anti-HIV treatment can dramatically reduce the risk of you passing on HIV to your baby.
There are two different ways in which these drugs can act.
First, they may reduce your viral load – the level of virus in your blood – so your baby is exposed to less of the virus while in the womb and during childbirth. The aim of HIV treatment is to get your viral load below 50 copies/ml. This is often referred to as an undetectable viral load.
Second, the drugs may 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 after they have been born when their mother is known to be HIV-positive.
Two drugs in particular have been shown to be very effective at preventing a mother from passing on HIV to her baby in the second of these ways. These are the nucleoside analogue (NRTI) AZT, and the non-nucleoside analogue (NNRTI) nevirapine.
The way in which these drugs are used (AZT on its own, or AZT or nevirapine in combination with other anti-HIV drugs) will depend on the damage HIV has done to your immune system, and the point in your pregnancy when HIV is diagnosed. Taking a combination of three of more anti-HIV drugs is often referred to as highly active antiretroviral therapy, or HAART for short.
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 it alone would limit your ability to benefit from nevirapine or related drugs in future, when you need them to protect your own health.
In good health?
If you have a good CD4 cell count and low HIV viral load and are not ill because of HIV, then 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 (injected) dose of AZT during delivery and have a caesarean rather than vaginal delivery. Another option is to take a short course of HAART during the last few months of pregnancy in order to get your viral load down to below 50 copies/ml. You then have the option of a planned vaginal delivery.
Your baby will receive treatment with AZT syrup for four-to-six 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 HAART during pregnancy, then the aim should be to get your viral load undetectable. You should continue to take anti-HIV treatment after your baby has been delivered.
Your baby will receive treatment with AZT syrup for four-to-six weeks after it is born.
High viral load?
If HIV has damaged your immune system, or if you have a high viral load, then you are advised to take HAART, including two drugs from the nucleoside analogue class (NRTIs), ideally AZT and 3TC, and either the 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 you will be able to have a planned vaginal birth.
Your baby will receive treatment with AZT syrup for four-to-six weeks after it is born.
Already on treatment?
If you become pregnant whilst taking HAART which is successfully suppressing your viral load, you are recommended to continue taking this treatment. You will need to have a special scan between weeks 18 - 20 of your pregnancy called an anomaly scan to see if your baby is developing with abnormalities.
Your baby will receive treatment with AZT syrup for four-to-six weeks after it is born.
If you become pregnant whilst taking HAART 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 AZT syrup for four-to-six 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 HAART immediately. This should be AZT, 3TC and nevirapine. These drugs are able to rapidly pass over the placenta into your baby.
Your baby will receive treatment with AZT syrup for four-to-six weeks after it is born.
Diagnosed during delivery or afterwards?
If you are diagnosed HIV-positive during delivery, or just after, then you should 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-to-six weeks. Not all the licensed HIV drugs are approved for children under three months of age.
Safety of treatments to prevent mother-to-baby transmission
There’s some evidence that there is 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.