How do HIV drugs protect the baby?
Reducing the risk of a baby becoming HIV positive was an early benefit of anti-HIV therapy.
PACTG 076 is the name of a famous joint American and French trial whose results were announced in 1994. This was the first study to show that using the drug AZT could protect the baby. Mothers took AZT before and during labour, and the baby received AZT for 6 weeks after birth. This reduced the risk of the baby becoming HIV positive from 1 in 4 (25 percent) to 1 in 12 (8 percent).
After 1994, this strategy was recommended for all HIV positive pregnant women in many industrialised countries.
Even further advances have been made over the last few years, especially since combination therapy became more common during the late 1990s. Transmission rates with combination therapy are now less than one percent.
AZT is still the only drug licensed for use in pregnancy. There is also a lot of experience of using it. Some doctors may still prefer to include it in a woman’s combination if she is pregnant.
However, a recent British and European report showed over 1000 women who had received non-AZT HAART in pregnancy. This report found that women receiving non-AZT HAART were no more likely to transmit HIV to their babies or have a detectable viral load than those on AZT-containing HAART. Nor were their babies more likely to have abnormalities.
Combination therapy or HAART (Highly Active Antiretroviral Therapy) are terms used to describe a strategy of using three or more drugs to treat HIV.
- Anti-HIV drugs are not effective for treating HIV individually (monotherapy), but they can be very effective in combination.
- For more info see the i-Base Introduction to Combination Therapy.
In the UK we are using AZT less and less in HIV regimens and other drugs like tenofovir (which is easier to tolerate than AZT) are being used more. If you are already on HIV treatment it is quite likely that you will be on a non-AZT regimen and, provided that it is working well, that your doctor will not change this.
A general rule of thumb is, what’s best for mum is best for baby.
It is important to remember though that despite huge advances and successes, there are still risks to be considered when using combination therapy for pregnant women. We are still learning about combination therapy in pregnancy.
You will need to discuss the benefits and risks of treatment with your healthcare team. This will include known and unknown short- and long-term factors. Nevertheless, the benefit of combination therapy far outweighs the risk.
When most of everything felt right, my health and relationship, having a baby, after more than 20 years since my last child, was the best feeling. After discussions with my partner and my doctor, I decided to have a baby. We did this while continuing with my current meds and of course not breastfeeding.
I was determined to do everything in my power to have an HIV-negative baby. Combination therapy has fulfilled my dreams of becoming a mother again.
Jenny, London
Transmission of HIV is when the virus passes from one person to another. When this is from mother to baby it is called mother-to-child (MTCT), perinatal or vertical transmission.
- Children who become HIV-positive in this way are called “vertically infected” children.
Viral load tests measure the amount of virus in your blood. The measurements are in copies per millilitre – for example 20,000 copies/mL
- Viral load is one measurement of the progression of HIV. The goal of treatment is to get your viral load to be undetectable, which is currently considered to be below 50 copies/mL.
- If a mother’s viral load is undetectable when her baby is born, the chance of mother-to-child transmission is almost zero.
Resistance
- If you just take one drug (monotherapy) or a combination of drugs that are not strong enough to get your viral load undetectable, then HIV can become resistant to the drugs.
- If the virus is resistant to a drug it will no longer work as well or it may not work at all.
- To avoid resistance, you need a combination of at least three antiretroviral drugs.
- It is important to avoid resistance in pregnancy.
- However using short-term monotherapy with AZT to prevent mother-to-child transmission (this is only used in some cases where a mother has a very low viral load) carries a very low risk of resistance.