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Barrier methods such as condoms and diaphragms are the most commonly used forms of birth control among HIV positive women. Sterilization is the second most popular method and hormonal contraception is the third. Hormonal contraceptives, when used correctly and consistently, are highly effective in preventing unintended pregnancy and are also useful for treating health conditions such as painful menstruation.
Despite their effectiveness and potential benefits beyond contraception, research indicates that HIV positive women use hormonal contraceptives less frequently than HIV negative women. Researchers estimate that in 2002, about 20% of HIV positive women used hormonal methods, compared with approximately 35% of HIV negative women. Usage rates vary widely, however, according to age, race/ethnicity, economic status, and other characteristics.
For all women, many factors must be considered in order to select the right type of contraception. A woman and her clinician should discuss the effectiveness, cost, ease of use, and side effects of various methods.
For HIV positive women, additional factors should be considered -- some obvious, others less so -- including preventing transmission of HIV and other sexually transmitted infections, interactions with antiretroviral drugs, risk of cardiovascular and other complications in the context of HIV and its treatment, and the desire to become pregnant in the future.
This article will describe the different types of available hormonal contraception and outline the facts every woman living with HIV should know when considering their use.
In the United States, almost half of all pregnancies are unintended. Hormonal contraceptives containing estrogens (typically ethinyl estradiol), progestins (compounds similar to natural progesterone, e.g., norethindrone), or a combination of both are among the most effective methods for preventing unplanned pregnancy.
Hormonal contraceptives work by a variety of mechanisms. Combination estrogen/progestin methods prevent ovulation (release of a mature egg) by interfering with triggering hormones produced by the hypothalamus and pituitary in the brain. Progestins suppress ovulation, impair the movement of sperm by thickening cervical mucous, and cause changes to the uterine lining that potentially prevent implantation of a fertilized egg.
Oral contraceptive pills (OCPs) are the most familiar example of hormonal contraceptives. OCPs have been one of the most popular forms of birth control since the early 1980s and are the type of hormonal contraception most commonly used by women between the ages of 15 and 44 in the United States. Several brands of estrogen/progestin combination pills and progestin-only pills are currently on the market.
Some hormonal contraceptives are injected or implanted in the body. Medroxyprogesterone depot injections (Depo-Provera) are administered every three months, while other injectables are given every one or two months. Contraceptive implants are inserted under the skin and slowly release progestins over a longer period. Implanon, which works for three years, was approved by the U.S. Food and Drug Administration (FDA) in 2006. Levonorgestrel implants (Norplant or Jadelle) are no longer available in the United States but are still used in resource-limited countries.
Other examples of hormonal contraceptives include the combination estrogen/progestin contraceptive patch (Ortho-Evra), a hormone-releasing contraceptive ring worn inside the vagina (NuvaRing), and intrauterine devices (IUDs) that gradually release hormones inside the uterus.
Finally, emergency contraception -- commonly known as the "morning-after pill" -- can prevent pregnancy when taken within 72 (and possibly up to 120) hours after unprotected intercourse. Plan B contains levonorgestrel; higher doses of some standard oral contraceptive pills can also be used on an emergency basis, if indicated by the woman's clinician.
Women with HIV tend to use different forms of contraception than HIV negative women. In an analysis conducted within the Women's Interagency HIV Study (WIHS), HIV positive women were less likely to use oral contraceptives, intrauterine devices, and the "rhythm method" (monitoring the menstrual cycle and avoiding sex when the likelihood of conception is greatest). Conversely, they were more likely to use male condoms for birth control, which also prevents transmission of HIV to their partners.
The proportion of HIV positive women using hormonal contraception has remained fairly stable between 16% and 21% from 1994 through 2002. Over time, there appears to be an increasing trend of HIV positive women using injectable progestin methods such as depot medroxyprogesterone or long-term implants.
Safety concerns around hormonal contraception fall into three broad areas: HIV disease progression, adverse side effects, and preventing infection.
Some researchers are concerned that using hormonal contraception could increase the risk of progression of HIV disease. These fears are partially based on theories about HIV's genes and the way hormones can regulate them, for example promoting faster viral replication. There have also been some studies suggesting that the presence of extra progesterone could make HIV disease progress more rapidly in animals.
In contrast to animal studies, however, human studies have found that varying levels of female hormones that occur naturally during the menstrual cycle or pregnancy do not appear to accelerate disease progression or increase plasma HIV viral load.
Only a few studies have looked specifically at hormonal contraception and HIV disease progression in women. All of these were observational studies, not randomized controlled trials (considered the "gold standard" for biomedical testing). This research has produced conflicting data, and it is still not clear whether using hormonal contraceptive methods promotes more rapid progression.
Two studies analyzing a cohort of Kenyan women found that hormonal contraception use at the time of HIV infection was associated with a higher HIV viral load "set point," a relatively stable level of virus in the body reached within months after infection. This finding was of interest because a higher viral set point has been linked to faster disease progression. However, two other studies -- one looking at the WIHS cohort and another in Kenya -- found no relationship between hormonal contraception and changes in viral load over time, and another study set in Uganda found no link between hormonal contraception and faster disease progression.
The second area of concern is whether HIV positive women are more susceptible to side effects or complications related to hormonal contraceptive use.
Research in HIV negative women has demonstrated an association between hormonal contraceptives and cardiovascular events, including myocardial infarction (heart attack), ischemic stroke, and pulmonary or deep vein thrombosis (blood clots). The increased risk was greatest with older oral contraceptive pills that contained high hormone doses, and appears mainly attributable to estrogen in combination products rather than those that include only progestins.
This increase in cardiovascular problems is most pronounced in women with other risk factors, including abnormal blood lipid levels, diabetes, and smoking. HIV infection and its treatment have been linked to higher cardiovascular risk -- some protease inhibitors, for example, can elevate blood cholesterol and glucose levels -- raising the question of whether positive women might be particularly susceptible to the adverse effects of hormonal contraceptives.
Cancer presents a similar issue. While decades of research have produced conflicting findings, there is evidence that certain combinations of contraceptive hormones may slightly increase the risk of breast cancer, while lowering the chances of developing ovarian or endometrial cancer. Recent research has found that HIV positive people have a higher rate of cancer overall than HIV negative people, but there appears to be little or no difference in the risk for these specific types of cancer.
Further studies are needed to clarify the link between hormonal contraception and cardiovascular outcomes and cancer in women with HIV. In the meantime, women and their providers should consider the full range of risk factors when choosing a contraceptive method.
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