HIV Risk Is Highest During Late Pregnancy, Postpartum Period

June 12, 2018

Women in late pregnancy or the postpartum period have the highest risk for acquiring HIV-1 from an infected partner, according to results of a new analysis.

“Quantifying the absolute and relative risks … of female HIV acquisition during pregnancy and the postpartum period, as well as further insight into whether any increased risk is attributable to biological or behavioral changes, is critical to inform efforts to prevent HIV,” the researchers write.


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To conduct their study, the researchers analyzed data from 2 randomized clinical trials, which assessed HIV acquisition during different stages of pregnancy among women in 2751 HIV-serodiscordant couples in 7 African countries.

Women underwent HIV screening monthly in one trial and quarterly in the other trial.

Over 48 months, there were 686 pregnancies and 82 incident HIV infections.

Results of the analysis showed that women in late pregnancy and the postpartum period had a higher risk of acquiring HIV than women in the nonpregnant period, after adjusting for variables such as condom use and HIV viral load.

For a 25-year-old woman not taking PrEP therapy, the HIV acquisition probability per condomless sex act with an HIV-infected male partner with a viral load of 10,000 copies/mL was:

  • 0.0011 during the nonpregnant period,
  • 0.0022 during early pregnancy,
  • 0.0030 during late pregnancy, and
  • 0.0042 during the postpartum period.

“In this prospective study, the risk of female HIV acquisition per condomless sex act was 3- and 4-fold higher during late pregnancy and the postpartum period, respectively, and remained significant after adjustment for factors known to effect HIV acquisition,” the researchers concluded. “Our findings underscore the need for continued counseling on the risk of HIV acquisition and options for enhanced HIV prevention for women during pregnancy and the postpartum period.”

—Amanda Balbi


Thomson KA, Hughes J, Baeten JM, et al; Partners in Prevention HSV/HIV Transmission Study and Partners PrEP Study Teams. Increased risk of HIV acquisition among women throughout pregnancy and during the postpartum period: a prospective per-coital-act analysis among women with HIV-infected partners. J Inf Dis. 2018;218(1):16-25.




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