Contraceptive Update

Network: Summer 1996, Vol. 16, No. 4

• Does Progesterone Increase HIV
• Hormonal Contraceptives and the Risk of STDs
• Progesterone and STDs: Selected Studies

A recent animal study has raised questions about the connection between hormonal contraceptives and the risk of HIV infection. The study found that rhesus monkeys given the hormone progesterone were more likely to become infected after vaginal exposure to simian immunodeficiency virus (SIV) than monkeys that had not been given the hormone.

The finding raises the possibility that contraceptives containing progestins, which are synthetic versions of the natural hormone progesterone, may increase the risk of acquiring HIV infection among humans. Oral contraceptives, injectables, Norplant and the LNg-IUD contain progestins.

When preliminary findings from this study were first reported, Family Health International distributed an information packet to more than 3,000 family planning providers. It included a "question and answer" sheet offering scientific information on contraceptive methods as they relate to this study and a concise list of related studies, with a brief description of their key findings.

"First and foremost, all couples at risk of any sexually transmitted disease (STD), including AIDS, should be advised to use latex condoms," said a cover letter from Dr. Theodore M. King, FHI's president, and Dr. Willard Cates Jr., FHI's corporate director of medical affairs.

"This long-accepted recommendation remains unchanged by the new study," their letter said. "While other barrier methods of contraception may provide a degree of protection from bacterial STDs, using latex condoms consistently and correctly during intercourse continues to be the most effective prevention strategy. Other options to reduce sexual transmission of HIV are possible. Abstinence from sexual activity is the safest one. Also, no sexual transmission is possible within a mutually-faithful relationship where both partners are uninfected."

While hormonal methods do not protect against STDs, they are excellent for preventing unintended pregnancy. They are safe, convenient to use and effective. Women should continue using them, but those women who are uncertain of their partners' STD or HIV infection status should also encourage their partners to use condoms. This "dual use" approach combines excellent contraception with the best practice for STD prevention.

Regarding the new study, findings from animal models do not necessarily translate into evidence of disease transmission in humans. More research is needed to examine whether any relationship exists between the progestins typically used in contraceptives and HIV transmission. Progesterone occurs naturally in every woman's body, with higher levels during the second half of the menstrual cycle and during pregnancy.

A National Institutes of Health (NIH) meeting of experts from NIH and other organizations reviewed the new findings. FHI's Dr. Cates, who chaired the meeting, says participants strongly encouraged no change in the long-standing advice to clients that progestin-only contraceptives are safe and effective choices, but offer no STD protection.

Women should consider the health risks they face from not using adequate contraception. Each year, an estimated 585,000 women die worldwide from complications due to pregnancy and childbirth.

FHI believes this new study should encourage physicians and other health care providers to advise women regarding their risks of STDs, including HIV. Clients at risk should be strongly encouraged to use latex condoms. The "question and answer" sheet and summary of studies follows.

Hormonal Contraceptives and the Risk of STDs A recent animal study has found that rhesus monkeys given doses of the hormone progesterone, a hormone produced naturally by the human body, are more likely to become infected after exposure to simian immunodeficiency virus (SIV), a virus similar to HIV in humans. More research is needed to assess the implications of this study for humans. The following questions and answers discuss current scientific knowledge about the relationship between hormonal methods and STDs. Question: What did the new study find? Answer: The study found that rhesus monkeys implanted with long-acting pellets of progesterone are more likely to become infected after vaginal exposure to SIV, compared with monkeys that have not been given the hormone. Of 18 monkeys treated with progesterone for six months, 14 became infected with the virus, compared to only one in 10 monkeys not implanted with progesterone. Researchers theorize that the reason progesterone-treated animals became infected more easily was that the vaginal epithelium -- the protective lining of the vagina -- was significantly thinner compared with the other monkeys. A thinner lining may provide an easier pathway for the virus. The National Institutes of Health, which financed the study, has said that the possible increased risk of SIV infection in monkeys does not necessarily have any implications for HIV transmission among humans. Further research is needed to examine any relationship between progestins and HIV transmission. Existing epidemiological studies among humans do not demonstrate consistent findings to support the postulated hormonal-STD risk. The new study was conducted at the Aaron Diamond AIDS Research Center in New York City, and the AIDS Animal Models Laboratory at the Laboratory for Experimental Medicine and Surgery in Primates in Tuxedo, NY. Study results are preliminary and have not yet been published in a scientific journal. Question: Are women who use hormonal methods at greater risk of acquiring HIV? Answer: Hormonal contraceptives provide effective protection against pregnancy, but offer virtually no protection against STDs, including HIV. Progestins, which are synthetic versions of the natural hormone progesterone, are used in all hormonal methods. While several studies have attempted to explore the relationship between HIV infection and progestin-containing contraceptives, the relationship remains unclear. Some researchers suggest the possibility that certain physiological changes that may be caused by progestin use may increase susceptibility to HIV. These include, for example, the thinning of the vaginal lining. Question: Should women using hormonal contraceptives continue using them? Answer: The results of this initial animal study are not expected to change the current consensus among public health and family planning organizations about the recommended uses for hormonal contraceptives. These methods are safe, effective and convenient to use, and many women benefit from using them. FHI joins NIH and the World Health Organization in saying the current data are not sufficient to change current family planning recommendations. However, the findings underscore the importance of barrier method use to prevent STD/HIV. Each woman should choose the contraceptive option that best suits her needs, in consultation with her physician or family planning provider. A mutually faithful monogamous couple, free of HIV infection, faces no risk of sexually infecting each other with HIV. Anyone at risk of any sexually transmitted disease should use latex condoms with every act of intercourse. Condoms can be used simultaneously with hormonal methods to provide excellent contraception with the best practice for STD prevention. Question: Should a woman at risk of STDs consider initiating hormonal methods if she is not currently using them? Answer: Anyone engaging in high-risk sexual behaviors -- whether using progestin methods or not -- should use latex condoms consistently and correctly. Hormonal methods can provide excellent contraception for couples using latex condoms for STD protection, and should be considered by people who wish to increase their protection against unintended pregnancies. The health risks from an unintended pregnancy are sizeable. Approximately 585,000 women worldwide die each year due to pregnancy-related complications, and millions more suffer major health problems related to unintended pregnancy or childbirth. Question: Do hormonal methods protect women against STDs? Answer: Hormonal contraceptives do not protect against STDs of the lower genital tract, the site where HIV is thought to be acquired. Oral contraceptives have been associated with increased detection of cervical STDs, but also are correlated with lower risks of symptomatic pelvic inflammatory disease (PID). Barrier methods of contraception (such as condoms, diaphragms and spermicides) offer better protection against STDs than other contraceptive methods but are somewhat less effective at preventing pregnancy. Question: What should a couple use to protect against both unintended pregnancy and STDs? Answer: Couples who want effective protection against pregnancy and STDs should consider using two contraceptive methods -- one to prevent pregnancy and latex condoms to prevent STDs. Condoms must be used correctly, and with every act of intercourse, to provide the best protection against STDs, including HIV. Other barrier methods, such as spermicides and the female condom, offer some protection against STDs, but further study is needed to document the degree of protection. When a man will not use a condom, these barrier methods may offer a degree of protection.

Daly CC, Helling-Giese GE, Mati JK, et al. Contraceptive methods and the transmission of HIV: Implications for family planning. Genitourin Med 1994; 70(2):110-17.

Choice of contraceptives may influence a woman's risk of contracting HIV, depending on her exposure to HIV. The relationship between oral contraceptives and HIV is unclear, although researchers suggest that some physiological changes caused by OC use may increase susceptibility to HIV. These include ectropion of the cervix; a higher incidence of chlamydia among OC users; and irregular menstrual bleeding. Injectable contraceptives containing progestins might also increase susceptibility to HIV by causing irregular menstrual bleeding and thinning of the vaginal lining. The relationship between IUD use and HIV risks also is inconclusive. Spermicides containing nonoxynol-9 inactivate HIV in the laboratory, but studies in humans (Kenya and Zambia) show conflicting results. No studies have been conducted to determine the effectiveness of the female condom in protecting against HIV.

Cates W Jr., Stone KM. Family planning, sexually transmitted diseases and contraceptive choice: A literature update--part I. Fam Plann Perspect 1992; 24(2):75-84.

Numerous studies have been conducted on the effects of contraceptive use on STD risks. Condoms alone, spermicides alone, or a combination of physical and chemical barriers appear to offer protection against some STDs. Male latex condoms provide an effective barrier against most bacterial and viral STD organisms, including HIV, the virus that causes AIDS. Vaginal pouches, including the female polyurethane condom, have been shown to be effective in vitro in protecting against HIV. Spermicides can kill or inactivate HIV in vitro, but few studies have been done in vivo. Spermicides also appear to be effective in vitro in protecting against other STDs, including gonorrhea and herpes. Barrier methods, used in combination with spermicides, also protect against infection.

Cates W Jr., Stone KM. Family planning, sexually transmitted diseases and contraceptive choice: A literature update--part II. Fam Plann Perspect 1992; 24(3):122-28.

Oral contraceptives, intrauterine devices (IUDs) and sterilization provide effective protection against pregnancy but offer no protection against STDs, including AIDS. Oral contraceptives appear to protect against symptomatic pelvic inflammatory disease (PID), yet the effect of OCs on HIV risks is unclear. IUD use may increase the risks of PID, but this risk usually occurs around the time of insertion. Tubal sterilization appears to reduce the risk of PID, but research is not conclusive. Sterilization protects against upper genital tract infections but not lower tract infections. Women who have cervical gonorrhea and chlamydia are at increased risk of endometritis following abortion, even when aseptic practices are followed. Couples who want effective protection against pregnancy and STDs may need to use two contraceptive methods -- one to prevent pregnancy, another to prevent STDs. Couples who want to use only one method are faced with trade-offs; they must risk increased likelihood of either pregnancy or STDs. Also, couples must assess the risks of childbirth. A more effective woman-controlled contraceptive method that also protects against STDs is needed.

Kapign SH, Shao JF, Lwihula GK, et al. Risk factors for HIV infection among women in Dar-es-Salaam, Tanzania. J Acq Immune Defic Syndr 1994; 7(3): 301-09.

A study of 2,285 women at high risk for HIV was conducted at three family planning clinics in Dar-es-Salaam. After controlling for known and potential risk factors, women who had used an IUD had a significantly increased risk for HIV infection. Women who used other contraceptives, including oral contraceptives, did not have an increased HIV risk. Other study findings were that women with two or more partners in the five years prior to the study had twice the HIV risk as women with only one partner. Also, women who experienced abnormal vaginal discharge (often an STD symptom) had an increased risk of HIV, and unmarried women, particularly women in cohabiting relationships, had the highest HIV-positive prevalence. HIV risks increased as women's and men's education levels increased.

Mati JKG, Hunter DJ, Maggwa BN, et al. Contraceptive use and the risk of HIV infection in Nairobi, Kenya. Int J Gynecol Obstet 1995; 48: 61-67.

A study of 4,404 women attending family planning clinics in Nairobi, Kenya examined the relationship between contraceptive use and HIV-1 infection. The study examined previous and current use of various methods, including oral contraceptives, injectable contraceptives, IUDs and condoms. There was no significant trend in risk of HIV infection with duration of use of oral contraceptives, injectables or IUDs. Prevalence of HIV was slightly elevated among women who had used OCs more than two years; however, researchers did not find this significant.

Saracco A, Musicco M, Nicolosi A, et al. Man-to-woman sexual transmission of HIV: Longitudinal study of 343 steady partners of infected men. J Acq Immune Defic Syndr 1993; 6(5): 497-502.

A study of 343 seronegative women (women who are not infected with HIV) found that condoms do offer protection against contracting HIV. The women were in stable monogamous heterosexual relationships. Their only risk for acquiring HIV was having sex with their HIV-infected partner. The annual seroconversion rate (the rate of women who became infected with HIV) was 5.7 percent to 9.7 percent among couples never or not always using condoms. The seroconversion rate fell to 1.1 percent among couples who always used condoms. Among the 22 women who used oral contraceptives, none became HIV-positive. One of two women using an IUD became HIV-positive.

Rehle T, Brinkmann UK, Siraprapasiri T, et al. Risk factors of HIV-1 infection among female prostitutes in Khon Kaen, Northeast Thailand. Infection 1992; 20(6); 328-31.

A study of sex workers in Khon Kaen in northeast Thailand was conducted to determine what factors increase HIV risks. More than 350 prostitutes were interviewed about sexual practices, including women who worked in brothels ("direct prostitutes") and women who worked in massage parlors ("indirect prostitutes"). Researchers found that direct prostitutes were 7.4 times more likely to be HIV-positive than indirect prostitutes. Users of injectable contraceptives had a 2.4 times higher risk of having HIV infection than did users of other contraceptives, including pills, condoms or IUDs. Researchers did not determine whether HIV-contaminated needles were the reason for higher HIV infection risks. Higher risks may have been associated with atrophy or weakening of the vaginal lining, making it more susceptible to tears during intercourse and creating a route for HIV infection. Other risk factors for HIV were duration of work in Khon Kaen (women who had worked in the town less than a month were 5.5 times more likely to be infected than those who had been there more than two years) and work in provinces with greater than 40 percent HIV prevalence.

Allen S, Lindan C, Serufilira A, et al. Human immunodeficiency virus infection in urban Rwanda. JAMA 1991; 266(12): 1657-63.

A study of 1,458 women in Rwanda examined risk factors for HIV infection. Thirty-two percent of the women were HIV-positive. Twenty-two percent of women had used oral contraceptives, and 20 percent had used injectables in the five years prior to the study. Both groups had a significantly higher prevalence of HIV infection than nonusers. However, higher-risk women -- those living alone or in nonmonogamous unions -- were more likely to have used oral or injectable contraceptives. When type of sexual relationship was taken into account, hormonal contraceptive use was not associated with increased prevalence of HIV infection. Factors increasing women's risk of HIV infection included being unmarried and having more than one lifetime sexual partner.