|Hormonal Contraception Does Not Appear To Increase
Using hormonal contraception does not appear to increase women's
overall risk of infection with the AIDS virus, report the authors
of a large study commissioned by the National Institute of Child
Health and Human Development of the National Institutes of Health.
The study, published on the Web site of the journal AIDS,
is the largest, most comprehensive of its kind to date. It followed
thousands of women in Africa and compared their patterns of contraceptive
use to their risk of infection with HIV.
The NIH project officer for the study, H. Trent MacKay, M.D.,
M.P.H, Chief of the Contraception and Reproductive Health Branch,
said the study findings do not provide a basis for changing current
recommendations regarding contraceptive use.
Dr. MacKay cautioned that, although hormonal contraception provides
an effective means of pregnancy prevention, it does not protect
against HIV or other sexually transmitted infections. Abstinence
is the only sure way to prevent sexual transmission of HIV, he
said. Barring abstinence, use of a latex condom, consistently and
correctly, is highly effective against HIV infection.
More than 100 million women around the world use hormonal contraception,
the study authors wrote. In all, 18 million women have been infected
with HIV, most during heterosexual relations. "Understanding whether
hormonal contraceptive use alters the risk of HIV acquisition among
women is a critical public health issue,"the study authors wrote.
The researchers studied use of the most commonly prescribed forms
of hormonal contraception: combined oral contraceptives, containing
estrogen and progestin, and depot-medroxyprogesterone acetate (DMPA),
an injected contraceptive containing progestin only.
Numerous studies have considered the issue of whether contraceptives
might increase a woman's risk of becoming infected with HIV. The
results of these studies, however, are inconclusive. The current
study was commissioned by NIH's National Institute of Child Health
and Human Development to overcome many of the limitations of the
previous studies. It was conducted primarily among women seeking
family planning services (rather than among high-risk women such
as sex workers) who more closely resemble the vast majority of
women using hormonal contraception worldwide.
The researchers undertook the study in Africa and Asia because
those parts of the world had a very high incidence of HIV infection
at the time the study was being planned. Because there are comparatively
fewer new cases of HIV infection in the United States, any U.S.-based
study would take far longer to provide results.
Charles Morrison, Ph.D., at Family Health International, in Research
Triangle Park, North Carolina, led the study, along with colleagues
from Fred Hutchinson Cancer Research Center in Seattle. The study
was conducted in Uganda, Zimbabwe, and Thailand, in collaboration
with researchers at Case Western Reserve University, in Cleveland,
Ohio, the University of California San Francisco, and the Johns
Hopkins University in Baltimore.
For the study, the researchers primarily recruited women at family
planning clinics in Uganda, Zimbabwe, and Thailand. The women ranged
in age from 18 to 35 years and were not infected with HIV at the
time they were recruited.
At the time they enrolled in the study, the women were either
using no hormonal contraception, or had used oral contraceptives
or DMPA for at least three months before the study began. Women
who were not using hormonal contraception used such methods as
condoms alone, diaphragms and spermicides, sterilization, withdrawal,
or periodic abstinence (the rhythm method), or used no method of
In the study, women seeking care were offered their choice of
contraceptive methods, either oral contraceptives or DMPA, as well
as condoms. The women were counseled on how to use these methods
and how to reduce their risk of becoming infected with HIV. The
researchers also examined the women for sexually transmitted infections,
and offered them treatment, if they needed it.
In all, 6,109 women participated in the study: 2,235 in Uganda;
2,296 in Zimbabwe; and 1,578 in Thailand. The women were tested
for HIV four to five times a year, for 15 to 24 months.
By the time the study had ended, 213 African women had tested
positive for HIV. In contrast, only four Thai women had become
HIV-infected. This appears to be primarily because the Thai government
mandated the use of condoms in the country's brothels during the
1990s, greatly reducing the heterosexual spread of HIV. Because
there were too few cases in Thailand for a valid statistical interpretation,
the researchers excluded the Thai cases from the final analysis.
When the researchers considered all of the 213 African HIV cases
together, they found no evidence that use of hormonal contraceptives
increased a woman's chances of becoming infected with HIV. "There
was no statistically significant difference in the risk of HIV
acquisition between users of combined oral contraceptives or DMPA
and women not using hormonal contraception," said Dr. Morrison.
The authors noted that their study could not rule out an increase
in risk for HIV infection among certain populations of "highly
exposed" hormonal contraceptive users — those already at
higher than normal risk of acquiring HIV, such as sex workers.
The authors added that the study results were "not inconsistent
with" a modest increase in risk for HIV infection associated with
hormonal contraceptive methods, particularly for DMPA, which was
seen in a study among high risk women in Kenya.
Among women who had genital herpes at enrollment, hormonal contraception
did not increase the risk of acquiring HIV. However, among women
without herpes at enrollment, hormonal contraception did increase
the risk of acquiring HIV when compared with the women who did
not have herpes at enrollment and who did not use hormonal contraception.
The researchers wrote that a biological explanation for this finding
remained "elusive," and said additional research is needed to confirm
and explain it. Previous studies have found genital herpes was
a risk factor for acquiring HIV.
"In summary, this large, multi-site study found no overall increased
risk of HIV acquisition associated with hormonal contraceptive
use," the study authors wrote. "This provides reassurance for women
in moderate and high HIV prevalence settings who need effective
contraception that any increased overall risk associated with hormonal
contraception is, at most, modest."
The NICHD sponsors research on development, before and after birth;
maternal, child, and family health; reproductive biology and population
issues; and medical rehabilitation. For more information, visit
the Institute's Web site at http://www.nichd.nih.gov/.
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Medical Research Agency — includes 27 Institutes and
Centers and is a component of the U.S. Department of Health and
Human Services. It is the primary federal agency for conducting
and supporting basic, clinical and translational medical research,
and it investigates the causes, treatments, and cures for both
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