These guidelines take into account the most recent information on the safety and effectiveness of different drug regimens, as well as concerns over resistance to some of the drugs used, including nevirapine.

These are the key recommendations contained in the guidelines - Antiretroviral Drugs for Treating Pregnant Women and Preventing HIV Infection in Infants:

• Women who need antiretroviral treatment for their own health should receive it in accordance with the WHO guidelines on antiretroviral treatment.

The use of antiretroviral treatment, when indicated, during pregnancy substantially benefits the health of the woman and decreases the risk of HIV transmission to the infant.

• HIV-infected pregnant women who do not have indications for antiretroviral treatment, or do not have access to treatment should be offered antiretroviral prophylaxis to prevent mother to child transmission of HIV using one of several antiretroviral regimens known to be safe and effective:

• Zidovudine from 28 weeks of pregnancy plus single-dose nevirapine during labour and single-dose nevirapine and one-week zidovudine for the infant.

This regimen is highly efficacious, as is initiating zidovudine later in pregnancy. · Alternative regimens based on zidovudine alone, short-course zidovudine + lamivudine or single-dose nevirapine alone are also recommended.

• Although expanding access to programmes to prevent mother to child transmission presents many challenges and single-dose maternal and infant nevirapine is the simplest regimen to deliver, programmes should consider introducing one of the other recommended regimens where possible.

The expansion of programmes to prevent mother to child transmission using single-dose nevirapine should not be hindered while necessary improvements in health systems are taking place to enable more complex antiretroviral regimens to be delivered.

The guidelines also refer to the issue of drug resistance.

Drug resistance linked to short-course regimens to prevent mother to child transmission that do not fully suppress the virus has been known since early 2000.

Programmes to prevent mother to child transmission and treat AIDS are rapidly expanding and antenatal clinics are able to identify more women who are HIV positive.

Since these women are all expected to eventually require treatment, potential resistance has become a far greater concern. However, concerns about resistance need to be balanced with the simplicity and practicality of delivering single-dose nevirapine compared with other regimens.

Antiretroviral prophylaxis using single-dose maternal and infant nevirapine remains a practical alternative when provision of more effective regimens are not feasible.

Progress in implementing programmes to prevent mother to child transmission based on single-dose maternal and infant nevirapine or other short course regimens should not be undermined.

New data being presented at the International AIDS Conference in Bangkok may offer a way of reducing resistance observed shortly after delivery and needs to be further assessed before any recommendation can be made to use this approach in programmes to prevent mother to child transmission.

WHO will regularly review the evidence base for the guidelines and will issue updated recommendations when warranted.

For further information, please contact: Iain Simpson, Communications Officer, on 06 068 3263 or Samantha Bolton, Communications Officer, on 06 068 3259.

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