The risk of acquiring HIV rises during pregnancy,
according to a study of women in Uganda's Rakai District
led by researchers at the
Johns Hopkins Bloomberg School of Public Health.
The increased risk for acquiring HIV remained even
after researchers controlled for behavior and other factors
that contribute to HIV risk. The findings, which are
published in the Sept. 30 edition of The Lancet,
suggest that the increased risk was likely due to
biological changes during pregnancy.
"We cannot generalize our findings beyond the Rakai
setting, and it would be important for other investigators
to verify our results. However, if women are at increased
risk of HIV acquisition during pregnancy, our findings
represent a public-health problem, both for the mother and
possibly her unborn infant," said the study's lead author,
Ronald Gray, the Robertson Professor of Reproductive
Epidemiology in the Bloomberg School's
Department of Population and Family Health Sciences.
"We believe that it would be prudent to warn women of this
potential risk of HIV acquisition during pregnancy and
promote safe sex or sexual abstinence where feasible."
The study supports the findings of two previous
studies that reported a greater risk of acquiring HIV
during pregnancy than after delivery. However, neither
study accounted for risk factors that contribute to HIV
risk.
Gray and his colleagues assessed 2,188 HIV-negative
women who were sexually active and were pregnant or
breast-feeding, and compared their rates of HIV acquisition
to 8,473 women who were neither pregnant nor lactating.
They compared the incidence rates of HIV during pregnancy
and breast-feeding with the rates during intervals when
pregnancy and breast-feeding were absent. The sexual
behaviors of husbands of married women in the study were
also assessed.
According to the investigators, the rate of HIV
acquisition was higher during intervals of pregnancy than
during breast-feeding or during intervals with neither. The
results of the study showed HIV incidence rates during
pregnancy were 2.3 percent per year whereas HIV incidence
rates were 1.3 percent per year during breast-feeding and
1.1 percent per year for women who were not pregnant or
breast-feeding. The risk for HIV remained higher even after
the investigators adjusted for other HIV risk factors.
"It is unlikely that the change in HIV risk we
observed is due to sexual behaviors. It may be attributed
to hormonal changes affecting the genital tract mucosa or
immune responses," Gray said.
Additional study authors from Johns Hopkins are
Xianbin Li and Henna Brahmbhatt, of the School of Public
Health; and Thomas C. Quinn and Steven J. Reynolds, of the
School of Medicine.
The research was funded by grants from the National
Institute of Allergy and Infectious Diseases, National
Institute of Child Health and Development, Henry Jackson
Foundation for the Advancement of Military Medicine, United
States Department of Defense, and Bill and Melinda Gates
Institute of Population and Reproductive Health at the
Johns Hopkins Bloomberg School of Public Health.