A government study said that the number of HIV positive pregnant women in South Africa has stabilized at 29 percent, but among expecting mothers in their early 30s the rate is still 40 percent.
The overall rate among pregnant women declined by just 0.1 points to 29.3 percent, but infections rose slightly among women in their 20s to 37.9 percent.
For women aged 30 to 34, the rate jumps to 40.4 percent.
"We seem to be losing the battle, but not yet the war," Health Minister Aaron Motsoaledi said at the release of the 2008 results in which nearly 40,000 women participated.
"The prevalence among women aged 25 years and above has stabilized at high and unacceptable levels," he said.
The virus, which infects just over one in 10 South Africans, continued to be one of the country's biggest challenges, Motsoaledi said.
The survey, carried out in state hospitals and clinics, is used as a benchmark by the government which runs the world's largest AIDS treatment program after years of failing to act timeously against the disease.