Ugandan women have higher risk of HIV infection when pregnant

Further evidence that pregnancy can increase a woman’s risk of becoming infected with HIV was presented today in a study from the Rakai district of Uganda. The findings, published in the October 1^st edition of The Lancet, show that after controlling for frequency of sexual activity and number of partners, pregnant women with HIV-positive husbands were more likely to contract HIV than non-pregnant women.

Researchers in the United States and Uganda carried out the comparison to determine whether physiological changes during pregnancy might account for higher rates of HIV transmission during pregnancy reported by a research group in Malawi, and also sought to control for sexual risk behaviour.

The study compared HIV acquisition in three groups of women participating in the Rakai Community Cohort (an ongoing study of sexual behaviour and HIV in a region of Uganda):

• All sexually active women.
• Married women whose husband’s self-reported sexual behaviour was also available for analysis.
• Married women in relationships with husbands who were HIV-positive.

The results were also analysed according to whether or not women were pregnant or breastfeeding.

They assessed 2188 HIV-negative sexually active women who were pregnant or breastfeeding and compared rates of HIV acquisition during these periods with 8473 non-pregnant and non-lactating women.

The investigators found that the HIV incidence rate was higher during intervals of pregnancy than during breastfeeding, or exposure intervals with no pregnancy or lactation. This excess risk remained significant even after adjustment for sociodemographic or behavioural factors that might increase HIV risk. HIV incidence rates were 2.3 per 100 person years during pregnancy, 1.3 per 100 person years during breastfeeding, and 1.1 per 100 person years in the women who were not pregnant or breastfeeding.

Although the investigators say that it’s important for other groups to confirm these results outside Rakai, they believe “it would be prudent to warn women of this potential risk of HIV acquisition and to promote safe sex or abstinence where feasible.”

The authors say that the high levels of oestrogen and progesterone during pregnancy can affect a woman’s susceptibility to HIV by causing changes in the genital tract, including the up-regulation of receptors needed by HIV and the attraction of T-lymphocytes vulnerable to HIV infection into the genital mucosa.

Implications for testing and counselling during pregnancy

“We have been too caught up in the difficulties of implementing even simple nevirapine-based strategies to see the bigger picture”, Dr James Macintyre of Witswatersrand University’s Perinatal HIV Research Unit commented in an accompanying editorial.

”The provision of HIV counselling and testing in pregnancy provides a unique opportunity to keep HIV-negative women negative, but in many settings post-test counselling is provided only for HIV-positive women or is minimal. The findings also highlight the futility of abandoning HIV testing in pregnancy and using universal PMTCT antiretroviral options.”

The findings also suggest that HIV testing strategies for pregnant women need to be reconsidered, says Dr Macintyre.

“Most programmes currently test once in pregnancy, and will not detect new infections late in pregnancy, or provide antiretroviral interventions to these high-risk mothers.”