2002-02-16 08:49:15 -- By BBC News Online's Caroline Ryan
So far, combination therapies for HIV have been considered a success, but there is some concern that the potential risks for HIV positive people who have children have not been assessed fully.
If the mother's health enabled you to use combinations that had less risk for producing genetic mutations, you could use them during pregnancy or at least during the last trimester
Dr Vernon Wilson
Experts already suspected that because the drugs act on the HIV viral DNA, the foetus DNA could also be affected if the woman was taking the drugs while pregnant.
Animal studies have suggested this could lead to cancers and other health problems - but the scientists stress that it is simply not possible yet to make a similar association in children.
Only close monitoring of the children's health throughout their lives would provide those answers, they said.
Pregnant HIV positive women are already warned of the potential risk to their child's health from the therapies, and Dr Vernon Wilson, who presented the work to the American Association for the Advancement of Science annual meeting in Boston, said treatments should not be altered in the light of his team's findings.
The study by his team at the Lovelace Respiratory Research Institute in Albuquerque, New Mexico, looked at the antiviral drugs AZT and 3TC.
These are nucleoside reverse transcriptase inhibitors (NRTIs), the first drugs given as HIV therapy and the most commonly used. They are often combined with another type of drug called a protease inhibitor in triple drug therapy.
The team looked at the umbilical cord blood cells of 51 children who had been exposed to the NRTIs in the womb including AZT, and compared them with 60 children in a control group.
The DNA of the children carries biological evidence if the children have been exposed to AZT. The researchers looked at two particular so-called marker genes, which the scientists used to check for DNA mutations.
It was found children exposed to both drugs had on average a two-fold increased frequency of DNA mutations, but what those mutations might mean for the children's health is unclear.
Levels of AZT were higher in children who had been given a combination of AZT and 3TC.
'No treatment change'
Dr Walker said the benefits of NRIT far outweighed the known risks to children, but research looking at what happened to children with genetic mutations had to take place.
He said more work was also needed to look at the genetic mutation risks of different combination drug therapies.
"If the mother's health enabled you to use combinations that had less risk for producing genetic mutations, you could use them during pregnancy or at least during the last trimester."
Rochelle Diamond, chair of the National Organization of Gay and Lesbian Scientists and Technical Professionals, is concerned that as HIV positive people are living longer because of the therapies, more are deciding to have children.
For this reason, she says more research needs to be done on the effect of the drugs on children.
"It's one thing to take these wonderful drugs to treat a disease that is really a death sentence for people if they don't treat it, but it's another thing when they consider trying to have a child, and treat themselves with these drugs which might hurt the children they are trying to conceive."
Meet Griffin, the grey parrot, whose astonishing vocal and physical skills are demonstrating just how smart the avian world really is