Cape Town — The Department of Health has revised its 2007 HIV figures for pregnant women, after stinging criticism from academics prompted a behind-the-scenes reassessment of its methods for estimating the numbers.

While the development was not explicitly spelt out at yesterday's release of the figures for last year, it nevertheless indicates an increased openness on the government's part about HIV/AIDS, after years of defensiveness and denial in former president Thabo Mbeki 's administration.

Last month the United Nations acknowledged the change, with its HIV/AIDS agency's regional head, Mark Stirling, saying SA was demonstrating "responsible leadership and governance".

Every year since 1990 the department has conducted an HIV and syphilis survey among pregnant women attending state clinics. It is one of the largest surveys of its kind in the world, and is important for monitoring and planning a response to SA's HIV/AIDS epidemic .

Last September, while still under the direction of controversial former health minister Manto Tshabalala-Msimang , the department published its 2007 antenatal clinic report with a national HIV prevalence figure for pregnant women aged 15-49 of 28%, emphasising that it was a drop on the 2006 figure of 29,1%.

The report was trashed by two of SA's top demographers, leaving the department in the embarrassing position of having to defend itself against speculation that the figures had been manipulated to give the impression the government's efforts to combat new HIV infections were bearing fruit.

Professors Rob Dorrington and David Bourne, in an article in the South African Medical Journal, argued that the department had used a new methodology which introduced a bias that lowered the provincial HIV figures.

The academics deduced that there had been a methodological change after spotting inconsistencies between district and provincial figures: for example, the report said HIV prevalence in the Western Cape had fallen from 15,1% to 12,6% between 2006 and 2007, yet no district had recorded a drop greater than one percentage point.

The 2007 report was removed from the department's website after the errors came to light, and a panel of experts worked with officials to fix the problems.

Yesterday's report contains a new national HIV prevalence figure for pregnant women of 29,4%. Read with the 2008 estimate of 29,3% and the 2006 figure of 29%, the trend suggests the epidemic is stabilising.

Blood samples were collected from 33927 women in all provinces last October. The report shows HIV prevalence has increased among women older than 30 in the past three years. Ntuli said researchers were cautious about interpreting the results, as fewer people were dying from AIDS as treatment became more widely available. HIV prevalence among women aged 30 to 34 increased from 37% in 2006 to 40,4% last year.