Antenatal testing for HIV and early diagnosis and taking HIV treatment can help to reduce the risk of passing HIV to your baby.

There are two ways in which HIV treatment reduces the risk of you passing on HIV to your baby.

Firstly, 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 birth. 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. Having an undetectable viral load means that HIV is still in your body, but at a much lower level.

Second, some anti-HIV drugs can also cross the placenta and enter your baby’s body where they can prevent the virus from taking hold. This is also why newborn babies are given a short course of anti-HIV drugs (this is called PEP, or post-exposure prophylaxis) after they have been born, if their mother is HIV-positive.

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.
• Having a sexually transmitted infection. You should have a sexual health screen early in your pregnancy and another one at 28 weeks.
• Having 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

• To avoid passing HIV to your baby, it is safest to formula feed because breast milk can contain virus. Help should be available with getting formula milk and feeding equipment. Ask your healthcare team about this and how to protect your confidentiality if a friend or family member asks why you are not breastfeeding.

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.

A baby’s development is most likely to be affected by any drugs you take during the first 14 weeks of pregnancy. AZT is the only drug that has been tested specifically for use during pregnancy and found to be safe. Only two drugs – ddI (didanosine, Videx, Videx EC) and efavirenz (Sustiva) – have caused any concerns about a possible link with birth defects. However, research now suggests that none of the anti-HIV drugs are linked to an increased rate of birth defects.

The anomaly scan pregnant women normally have between weeks 18 and 20 of a pregnancy can check for possible physical problems in your baby’s development.

The risk of your baby contracting HIV is reduced if you have a planned caesarean section. This is usually 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 a 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 monitor you carefully and make sure that your labour doesn’t last too long to reduce the risk of you passing on HIV to your baby.

Breastfeeding carries a risk of 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 (this seems to make the transmission of HIV more likely).

In the UK and other countries where safe alternatives to breastfeeding are available, you are advised to feed your baby with formula milk from birth.

Detailed advice and support on how to do this is available from your healthcare team, as well as from support organisations. Ask your healthcare team or support organisation if you have difficulty meeting the cost of formula and the equipment needed.

For help and support on explaining to others why you are not breastfeeding when you want to keep your HIV status confidential, talk to other mothers with HIV about how they have successfully done this. Your healthcare team or support organisation can also help you with this.

See the British HIV Association guidelines on infant feeding for more information (www.bhiva.org).

You are likely to be looked after by a multidisciplinary antenatal team during your pregnancy. Your care will still be offered at your HIV clinic, but as well as your HIV doctor and clinic staff, you are likely to see an obstetrician, a specialist midwife and a paediatrician. Other people you may see, depending on your wishes or needs, could include a peer support worker, community midwife, a counsellor, a psychologist, a social worker or a patient advocate.

Good antenatal care will help support you in reducing the risk of transmission of HIV as well as staying well during your pregnancy. Your healthcare team and support organisation can help you adhere to any treatment you need to take and answer questions you may have about your health and that of your baby. They can provide support and advice on your eligibility for free NHS treatment, as well as help with any other issues you might have, such as housing, finances or alcohol and recreational drug use.