3% incidence of HIV in pregnant women shows importance of repeat HIV testing in pregnancy

A South African study has revealed that a significant number of women are being infected with HIV during pregnancy. In the June 19^th edition of AIDS, researchers report that 3% of women who had a negative HIV test result when first accessing antenatal services subsequently tested positive later in the pregnancy.

“Pregnant women continue to represent a vulnerable population, and HIV testing late in pregnancy or labor offers an additional opportunity to prevent mother to child transmission or prevent further horizontal transmission in the community as well as ensure continued care for women who seroconvert during pregnancy”, comment the investigators.

HIV prevalence amongst pregnant women in South Africa is estimated to be 28%. It is recommended that all women should be offered voluntary HIV testing and counselling when they first access antenatal services. However, repeat testing of women testing negative is rarely offered.

This practice means that infections at the time of the first visit may remain undetected because of low antibody levels and infections acquired during pregnancy will not be diagnosed unless a subsequent test is offered.

Investigators therefore offered a repeat HIV test to women using antenatal services at one rural and two urban clinics in Eastern Cape and Free State between July 2006 and April 2007. Their aim was to determine HIV incidence during pregnancy and its risk factors.

A total of 5233 pregnant women registered for antenatal care and 3742 (79%) accepted an HIV test. HIV prevalence amongst these women was 28%.

The investigators referred 2377 women who initially tested negative for a repeat HIV test between weeks 36 and 40 of pregnancy. A total of 1278 (53%) had such a test.

Of these women, 72 (3%) were HIV-positive. They were tested an average of 24 weeks after their initial screening for the virus, yielding an incidence rate of eleven per 100 person years.

There was a non-significant trend for a higher risk of HIV incidence for women attending the urban rather the rural clinics (risk ratio = 1.37; 95% CI: 0.86 to 2.17, p =0.182).

HIV was higher amongst women aged 25 to 29 (4%) and 30 to 40 (5%) than amongst those aged below 20 (2%). There was also a lower incidence rate (1%) amongst women who had received a tertiary education than those with lower levels of education (3%).

Single and divorced women had a higher incidence of HIV during pregnancy (3%) than married women (2%).

Only 40% of women used a condom during pregnancy. However, condom use did not differ between women who contracted HIV and those who did not.

The investigators conclude, “In light of the above findings, public health programs need revisiting to ensure that HIV retesting in pregnancy is implemented, reinforce the need for continued education on prevention during pregnancy and extend the use of female-controlled prevention methods such as microbicides when proven well tolerated and efficacious during pregnancy.”