BOSTON — Biological changes during pregnancy and the postpartum period may increase a woman’s risk for HIV, according to findings presented at CROI and published in The Journal of Infectious Diseases.
The results of an observational study conducted in Africa among serodiscordant couples with an HIV-infected male partner showed that the risk for HIV transmission in women was threefold higher during the second and third trimesters of pregnancy and fourfold higher during the 6-month postpartum period, according to Renee Heffron, PhD, MPH, assistant professor of global health and epidemiology at the University of Washington, and colleagues.
The researchers said the results show the need to scale-up HIV prevention and testing in pregnant and postpartum women in areas with high HIV prevalence.
“HIV acquisition during these times is quite detrimental to maternal as well as infant health,” Heffron said at a news conference here. “Thus, a more complete understanding of the possible link between pregnancy and HIV risks could have important implications for HIV prevention.”
The researchers enrolled 2,751 serodiscordant couples in two longitudinal HIV prevention studies in seven eastern and southern African countries. All women in the study were HIV negative. Couples were followed prospectively for up to 48 months. Sexual frequency and condom use were reported monthly, and HIV and pregnancy testing occurred either monthly or quarterly, Heffron and colleagues said.
Using modeling, they compared the probability of male-to-female HIV transmission per sex act by reproductive stage. Their analysis accounted for factors known to affect HIV acquisition, such as condom use, the age of the women and whether the women were using pre-exposure prophylaxis (PrEP) The reference case for HIV transmission probability was a condomless sex act between a woman aged 25 years not using PrEP and a male partner with HIV RNA of 10,000 copies/mL.
According to the results, pregnancy incidence was 12.5 per 100 women-years (95% CI, 11.52-13.55), and there were 78 HIV transmission events included in the analysis. The HIV transmission probability increased with each reproductive stage: from 1.05 per 1,000 sex acts when women were not pregnant, to 2.19 per 1,000 sex acts in the first trimester, 2.97 in the second and third trimester and 4.18 in the postpartum period.
The results were similar after Heffron and colleagues adjusted for condom use, age, PrEP use and HIV viral load of their male partners.
“In statistical comparisons, there is a significant increase in HIV acquisition during pregnancy and postpartum relative to the period not related to pregnancy,” Heffron said. “Because our study accounts for condom use and other factors known to affect HIV acquisition, and because we calculated a per-act probability, our findings suggest that biological changes during pregnancy and postpartum may increase HIV risk.”
Heffron said they are not currently investigating which biological mechanisms may be responsible for the increased risk, but they hypothesize that changes in hormones or immune function may explain the association. The findings align with some previous studies, she said.
“These are observational data, so women weren’t randomized. It’s very difficult to conceive of ways we could do randomized studies in this population,” she said. “[But] if you put these together with other data, we do start to see a bit of a trend showing an increased risk during pregnancy and postpartum.” – by Gerard Gallagher
Heffron R, et al. Abstract 45. Presented at: Conference on Retroviruses and Opportunistic Infections; March 4-7, 2018; Boston.
Thomson KA, et al. J Infect Dis. 2018;doi:10.1093/infdis/jiy113..
Disclosure: Heffron reports no relevant financial disclosures.