Sexually transmitted infections (STIs) occur in all plants and animals that reproduce sexually, including humankind (Baskin, 1999). Unfortunately, sexually transmitted infection among people has come to be regarded as a moral issue. This has resulted in a powerful social stigma that has highly negative public health consequences.

Sexually transmitted infections are among the most common infections that occur in the United States today, yet most men and women of reproductive age (18–44) dramatically underestimate the national prevalence of such infections and their own personal risk of acquiring one (KFF, 1998a). There are two major reasons for this lack of awareness. First, many of these infections are asymptomatic. Second, the strong social stigma about people with STIs prevents open discussion of this health problem (KFF, 1998b). As a result, many sexually active women and men today do not know the names of some of the most common and potentially damaging STIs, and they are not being tested or treated for them (KFF, 1998a). And unless they practice safer sex, they do not know if they are placing themselves or their partners at risk during sexual activity. Further, they are not informed about the potential,serious, long-term health consequences they face in the future if they fail to seek treatment for an STI that they may have at the present time.

People who know they have a sexually transmitted infection often feel the effects of the social stigma against them and are secretive about their condition. This has led to what has come to be termed a “hidden epidemic” (Eng & Butler, 1997). So many women, men, and teens in the U.S., in fact, have STIs that it is more the norm for millions of Americans. Only open discussion, based on accurate information about the scope of the problem, can help more people become aware of the personal and public health implications of the current STI epidemic. Armed with information and freed of the fear of stigma, sexually active individuals will be able to make responsible decisions about seeking testing and treatment and about safer sexual practices that can prevent infection. And greater awareness of this epidemic among public health professionals and legislators can lead to more practical and successful strategies to combat the epidemic. For example, in one study, only one out of 10 of the women surveyed reported that during their first visit for routine gynecological or obstetric care their doctor had raised the subject of STIs other than HIV/AIDS (and only 19 percent reported that the doctor had raised the latter). This fell far short of the 1996 Guidelines for Women’s Health Care recommended by the American College of Obstetricians and Gynecologists — that all women under the age of 65 receive evaluation and counseling on STIs as part of a routine assessment (KFF, 1997).

Incidence of Sexually Transmitted Infections

• It is estimated that more than 15 million new cases of sexually transmitted infections are diagnosed each year in the U.S. (Cates, 1999) — Approximately one-fourth of these new infections occur among teenagers (CDC, 2000a).

• By the age of 24, one in three sexually active people will have contracted an STI (KFF, 1998b); moreover, at least one in four Americans — perhaps as many as one in two — will contract an STI at some point in their lives (AGI, 1993).

• At least 65 million people — more than one in five Americans — are believed to be infected with a viral STI other than HIV (NCHSTP, [1999]). These incurable infections, such as genital herpes, human papilloma virus (HPV), and hepatitis B, have consequences ranging from recurrent painful outbreaks to chronic liver disease to cancer(CDC, 2000a).

• Rates of curable STIs in the U.S. are the highest of any country in the developed world and are higher than in some developing regions (Eng & Butler, 1997). An illustration of this is the rate of syphilis in the U.S. which, despite a decline during the 1990s (DSTDP, 1998), is still more than 15 times that of Canada and more than six times that of England (Eng & Butler, 1997). The same is true of gonorrhea — despite declines over the last 20 years (DSTDP, 1998), the reported incidence of gonorrhea in the U.S. in 1999 was 133 per 100,000 persons per year (CDC, 1999), compared to Sweden’s 3.0 per 100,000 and Australia’s 18.1 per 100,000 (Eng & Butler, 1997).

• Rates of STIs other than syphilis and gonorrhea have been going up. During the 1980s, genital chlamydia became the most prevalent bacterial STI in the U.S., and in 1996 there were an estimated 3 million new cases — this made chlamydia the most frequently reported infectious disease in the country. Genital herpes infections increased eleven-fold during the 1970s and 1980s. At least one million new genital herpes infections occur each year and cause at least 10 times more genital ulcer cases than does syphilis. Cases of HPV have risen as well, with an estimated incidence of 5.5 million new infections each year. HPV infections of the cervix and vagina are now the most common STIs among sexually active young women (KFF, 1998b).

• Although a preventive vaccine is available for hepatitis B, incidence and prevalence of this sexually transmitted viral infection remain high (KFF, 1998b) — It is estimated that 120,000 infections occur through sexual transmission annually, and young adults are the most commonly infected. Approximately 417,000 people are currently living with chronic sexually acquired HBV infection (CDC, 2000a).

• The rise of STIs presents family planning clinics with higher costs and new challenges. In 1990, for example, 40 percent of all medical visits to Planned Parenthood of Wisconsin involved testing or treatment for STIs, compared with only 10 percent of visits in 1980 (Donovan, 1991).

The Costs of Sexually Transmitted Infections

• The direct costs of treating STIs and their complications are estimated to be $8.4 billion per year. These estimates do not include indirect, non-medical costs, such as lost wages and productivity due to STI-related illness, or the costs that ensue when STIs are transmitted to infants, which can result in significant life-long expenditures (KFF, 1998b).

• Early screening and other preventive measures are extremely cost-effective. Screening for chlamydia is a good example. A study in Baltimore, Maryland, found that without screening for chlamydia, 152 out of 7,699 women would develop pelvic inflammatory disease (PID) as a consequence of their untreated chlamydial infection, leading to a cost of $676,000. Screening under the Centers for Disease Control and Prevention (CDC) standards would prevent 64 cases of PID among these women and save $231,000. Screening all women less than 30 years of age in this population would prevent another 21 cases of PID and save an additional $74,000 (Howell et al., 1998).

Effectiveness of Screening for Sexually Transmitted Infections

• In parts of the United States where large-scale chlamydia programs have been instituted, prevalence of disease has steadily declined. During 1988–1997, among women aged 15–44 who participated in Health and Human Services (HHS) screening programs in family planning clinics in Alaska, Idaho, Oregon, and Washington, there was a 67 percent decline in positive chlamydia tests (from 9.3 percent to 3.1 percent) (DSTDP, 1998).

• Chlamydia appears to be declining in the United States. This is primarily due to increased efforts to screen and provide treatment for women with chlamydia. It is estimated that incidence of chlamydia has declined from more than 4 million annual infections in the early 1980s to the current level of 3 million annual infections (Cates, 1999).

• From 1994–1997, among women under 45 years of age who participated in HHS screening programs in family planning clinics in Colorado, Montana, North Dakota, South Dakota, Utah, and Wyoming, positive chlamydia tests declined by 23 percent (from 3.9 percent to 3 percent) (DSTDP, 1998).

• Although the CDC has found that case reporting of chlamydial infections is improving, it remains incomplete in many areas of the country. This is true despite the fact that, in 1999, 49 states, the District of Columbia, and New York City required reporting of chlamydia and reported cases to the CDC (CDC, 1999). The data are limited due to several factors:

• inconsistent compliance with public health laws on the part of health care providers and laboratories who are supposed to report cases to local health authorities

• large numbers of asymptomatic persons who can be identified only through screening

• limited resources to support screening activities

• incomplete information management systems for collecting, maintaining, and analyzing case reporting and prevalence data (DSTDP, 1998)

Disproportionate Impact of STIs: Women, Teens, Minorities

• Men and women of all ages, racial and ethnic backgrounds, and income levels acquire STIs. However, women, teenagers, the poor, and some minority racial and ethnic groups, especially African Americans, bear the brunt of STI infections. Women are more severely affected because they are physiologically more susceptible to infection and less likely to experience symptoms, which makes detection more difficult until serious problems develop (DSTDP, 1998; KFF, 1998b).

• Women account for about half of all sexually transmitted infections that occur each year, but they suffer more frequent and severe long-term consequences than men (AGI, 1993).

• Women are customarily but incorrectly stigmatized as “carriers” of sexually transmitted infections. However, genital infections, including HIV, are more easily passed from men to women than from women to men (KFF, 1998b). A woman’s risk of acquiring gonorrhea from a single act of intercourse may be as high as 60 to 90 percent, while transmission of gonorrhea from a woman to a man is about 20 to 30 percent (Eng & Butler, 1997). A study published in 1992 found that among couples in which only one partner was initially infected with herpes simplex
virus, the annual risk of viral transmission was 18.9 percent from man to woman, but only 4.5 percent from woman to man (Mertz et al., 1992).

• Each year in the United States, more than 1 million women experience episodes of acute pelvic inflammatory disease (NIAID, 1998), most often as a consequence of an untreated or inadequately treated case of an STI such as chlamydia, gonorrhea, or bacterial vaginosis (OWH, 1997; Eng & Butler, 1997). PID is a cause of ectopic pregnancy. The rate of ectopic pregnancy has increased five-fold in the past two decades (OWH, 1997). Approximately 100,00 ectopic pregnancies occur each year. Many of these result from tubal damage caused by sexually transmitted infections. Ectopic pregnancies are the leading cause of pregnancy-related deaths in the first trimester and account for 9
percent of all pregnancy-related deaths in the U.S. (CDC, 2000b).

• A single episode of PID can permanently damage the fallopian tubes. Such damage is even more common following a second or third episode of PID. It is the only cause of infertility that is preventable, accounting for as many as 30 percent of infertility cases in women (OWH, 1997).

• Infected women can transmit an STI to their offspring during pregnancy and childbirth, or after birth as a result of breast-feeding or close direct contact. The results can be devastating — STI infections can cause spontaneous abortion, stillbirth, infant death, premature delivery, low birth weight, chronic respiratory problems, blindness, and mental retardation or other manifestations of severe brain damage (Eng & Butler, 1997).

• Bacterial vaginosis (BV) is the most prevalent cause of vaginal symptoms among women of childbearing age (Holmes et al. , 1999). In the past, it was considered to be a benign condition, but has more recently been shown to be associated with premature delivery, low birth weight, and PID (Eng & Butler, 1997), and BV infections may increase susceptibility to HIV infection (Sewankambo et al. , 1997). Although BV does not affect conception rate, BV in a pregnant woman causes an increased risk of late miscarriage and is associated with a two-fold risk of miscarriage in the first trimester (Ralph et al. , 1999). While women who only have sex with women seem to be at less risk for some bacterial STIs compared to women who have sex with men, BV and genital HPV are two STIs that are not uncommon among this population (Eng & Butler, 1997). A 1995 study of monogamous lesbian couples found that the likelihood of one member of a couple having BV was nearly twenty times greater if her partner had BV (Berger et al. , 1995).

• Of the 15 million people who contract STIs annually, one-quarter, or 3,750,000, are teenagers (KFF, 1998b). Many of these young people suffer long-term health problems as a consequence of their infection.

• Some STIs, especially syphilis and gonorrhea, are far more common among African Americans and Latinos than among whites. In 1999, 77 percent of the total number of cases of gonorrhea reported to the CDC occurred among African-Americans. This rate is 30 times higher than for non-Hispanic whites. The rate of gonorrhea in Hispanics was reported to the CDC as three times the rate of non-Hispanic whites. The most recent epidemic of syphilis was most commonly found in heterosexual minority populations. In 1999, 75 percent of all cases of primary and secondary syphilis occurred among African Americans. This rate is 30 times higher than the rate of 0.5 per 100,000 persons among non-Hispanic whites. The 1999 rate of primary and secondary syphilis among Hispanics was four times greater than the rate among non- Hispanic whites (CDC, 1999).

HIV and AIDS

• As of December 1999, the cumulative number of AIDS cases in the U.S. reached 724,656. Total deaths from complications related to AIDS were 430,441 (CDC, 2000d). In 1999, an estimated 320,282 persons were living with AIDS. Declines in AIDS incidence and deaths began in 1996 and continued into 1998 and have correlated with the widespread use of potent antiretroviral therapies. (CDC, 1999). Despite this decrease, AIDS remains a leading cause of death in most age groups — in 1997 it was the fifth leading cause of death in the 25–44 age group, the seventh leading cause of death in those aged 15–24, and the ninth leading cause of death in those aged 5–14 (Ventura et al., 1998).

• The greatest proportion of AIDS cases in the U.S. has always been among people in the 25–44 age group. In 1996, nearly 75 percent of Americans diagnosed with AIDS were in this group (NCHSTP, 1998f).

• While there has been a declining trend in the number of AIDS diagnoses, the number of HIV diagnoses has remained relatively stable. Estimates suggest that 800,000 to 900,000 Americans are now living with HIV, and as many as one-third don’t know that they have the
virus (CDC HIV Prevention, 2000), and at least 40,000 new HIV infections occur each year (CDC, 2000c).

• AIDS has had a disproportionate impact on minorities. In 1999, more African- Americans were reported with AIDS than any other racial/ethnic group. An estimated two-thirds (63percent) of all women with AIDS were African-American as were 42 percent of all men. Hispanics represented 13 percent of the U.S. population in 1999, but accounted for 19 percent of the total number of new AIDS cases reported. (CDC, 2000c).

• AIDS has had a devastating impact on women, especially women of color. African-American women and Hispanic women together represent less than one-fourth of all U.S. women, yet they account for more than three-fourths of AIDS cases reported to date among women in the U.S. (NCHSTP, 1998b). It is estimated that Africa-American women account for 64 percent of new HIV infections among women. Hispanic women represent 18 percent of all new HIV infections among women (CDC, 2000c). In 1996, AIDS was the fourth leading cause of death among all U.S. women aged 25–44, and the leading cause of death among African-American women in the same age group. Although AIDS-related deaths among both men and women are decreasing due to recent advances in treatment, the decline in the death rate among women is not as rapid as it is among men (NCHSTP, 1998b).

• Young and minority women are disproportionately affected by other STIs, such as gonorrhea, syphilis, and chlamydia. These STIs make women two to five times more vulnerable to HIV infection (NCHSTP, 1998b).

• From 1996 to 1997, AIDS incidence among men who have sex with men declined by 18 percent and deaths declined by 49 percent (NCHSTP, 1998c). However, among all men diagnosed with AIDS, men who have sex with men still accounted for the largest proportion of cases (nearly 60 percent) in 1999 (CDC, 2000c).

• During the early 1990s, an estimated 1,000–2,000 infants were born with HIV infection each year (NCHSTP, 1998e). These numbers have dropped dramatically since clinical trials in 1994 demonstrated that HIV-infected women could reduce the risk of transmitting the virus to their babies by as much as two-thirds by administering the drug zidovudine (AZT) during pregnancy, labor, and delivery, and by giving their
babies AZT for the first six weeks after birth. However, despite declines of perinatally acquired AIDS cases in all racial and ethnic groups, the majority of cases continue to occur among African-American and Latino children (NCHSTP, 1998f). African-American children represent nearly two-thirds of all pediatric AIDS cases (CDC, 2000c).

STI-Related Reproductive Cancers and Non-HIV, STI-Related Deaths

• HPV is associated with at least 80 percent of invasive cervical cancer cases, and women with HPV infection of the cervix are 10 times more likely to develop invasive cervical cancer than are women without such infection (Eng & Butler, 1997). In 1999, an estimated 12,800 cases of invasive cervical cancer are expected to occur, with about 4,800 women dying from this disease (Landis, et al., 1999). A study published in 2001 presented yet to be duplicated evidence that previous infection with certain types of chlamydia may also be associated with the development of cervical cancer (Anttila, et al., 2001).

• Certain types of sexually acquired HPV are also now considered to be a cause of most cancers of the vagina, vulva, anus, and penis. Although each of these cancers occurs less frequently than does cervical cancer, taken together they equal nearly half the number of cases of cervical cancer in the United States (Eng & Butler, 1997).

• Among the largest number of deaths related to STIs other than HIV are those due to cervical and other HPV-related cancers; chronic liver disease and liver cancer caused by hepatitis B virus; PID and ectopic pregnancy; and various complications of pregnancy (Eng & Butler, 1997).

Health Risks for Men

• Every year 500,000 men develop epididymitis, an inflammation of the testicular tubes in which sperm mature. Most cases that occur among sexually active men are caused by STIs such as chlamydia and gonorrhea. Untreated, the infection can involve an entire testicle and lead to decreased fertility, or it can involve both testicles, which can lead to sterility. Epididymitis caused by sexually transmitted E. coli infection occurs among homosexual men who are the insertive partners during anal intercourse (Holmes et al., 1999; CDC, 1998b).

• As a group, men between the ages of 20 and 24 suffer some of the highest rates of gonorrhea (NCHSTP [1999]).

• Chlamydia places men at risk for disability from Reiter’s syndrome, a form of arthritis that seems to be more common in men than in women (Eng & Butler, 1997). In the U.S., of the estimated one and a half million men who get chlamydia each year (Groseclose et al ., 1999), one percent (15,000) may develop Reiter’s Syndrome (Keat, 1983), and one third of these men — perhaps 5,000 men each year — will become permanently disabled (Friedman et al., 1998).

• HPV can lead to cancer of the penis, and to cancer of the anus in men as well as women (Eng & Butler, 1997).

• Men are more commonly infected with chancroid than are women. A sexually transmitted bacterium, chancroid was once very common but reported cases have fallen to fewer than 300 per year in the United States. However, it remains an especially dangerous STI because it causes sores that increase the chances of getting HIV (Holmes et al., 1999).

Additional Resources

The Alan Guttmacher Institute (AGI)
120 Wall Street, 21st Floor
New York, NY 10005
212-248-1111
212-248-1951 (fax)

1120 Connecticut Avenue, NW, Suite 460
Washington, DC 20036
202-296-4012
202-223-5756 (fax)
info@agi-usa.org
www.agi-usa.org

American Social Health Association (ASHA)
P.O. Box 13827
Research Triangle Park, NC 27713
919-361-8400
919-361-8425 (fax)
www.ashastd.org

Kaiser Family Foundation (KFF)
2400 Sand Hill Road
Menlo Park, CA 94025
650-854-9400
650-854-4800 (fax)
www.kff.org

National Center for HIV, STD, & TB Prevention
Centers for Disease Control and Prevention
Atlanta, GA 30333
nchstp@cdc.gov
www.cdc.gov/nchstp
Toll-free voice information: 888-232-3228
CDC STI Hotline: 800-227-8922

Cited References
AGI — The Alan Guttmacher Institute. (1993). Testing
Positive: Sexually Transmitted Disease and the Public
Health Response. New York: The Alan Guttmacher
Institute.
Altman, Lawrence K. (1981, July 3). “Rare Cancer Seen in
41 Homosexuals.” New York Times, A20.
Antilla, Tarja, et al. (2001). “Serotypes of Chlamydia
trachomatis and Risk for Development of Cervical
Squamous Cell Carcinoma.” The Journal of the
American Medical Association, 285 (1) (3 January), 47-
51.
Baskin, Yvonne. (1999). “Birds, Bees, and STDs.” Natural
History, 108(1) (February), 52–55.
Berger, S.J., et al. (1995). “Bacterial Vaginosis in Lesbians:
A Sexually Transmitted Disease.” Clinical Infectious
Diseases, 21(6) (December), 1402–5.
Cates, Willard. 1999. “Estimates of the Incidence and
Prevalence of Sexually Transmitted Diseases in the
United States.” Sexually Transmitted Diseases, 26 (4)
(April 1999), s2-s7.
CDC — Centers for Disease Control and Prevention.
(1998a). HIV/AIDS Surveillance Report, 10 (No. 2).
Atlanta, GA: Centers for Disease Control and
Prevention.
_____. Sexually Transmitted Disease Surveillance 1999.
Department of Health and Human Services: Center for
Disease Control and Prevention. (1999).
_____. (1998b). 1998 Guidelines for Treatment of Sexually
Transmitted Diseases. Morbidity and Mortality Weekly
Report (MMWR), 47 (No. RR-1): p. 86.
_____. (2000a, accessed 2001, January 25). Tracking the
Hidden Epidemic: Trends in STDs in the United States
2000 [Online].
http://www.cdc.gov/nchstp/dstd/Stats_Trends/Trends
2000.pdf
_____. (2000b, accessed 2001, January 25). Fact Sheet:
Risk of Ectopic Pregnancy after Tubal Sterilization
[Online]
http://www.cdc.gov/nccdphp/drh/mh_ectopic.htm.
_____. (2000c, accessed 2001, January 24). HIV Prevention
Strategic Plan through 2005 [Online].
http://www.cdc.gov/nchstp/od/news/draft.plan.pdf.
_____. (2000d, accessed 2001, January 25). Basic Statistics:
Cumulative AIDS Cases [Online].
http://www.cdc.gov/hiv/stats/cumulati.htm.
Donovan, Patricia. (1991). “Family Planning Clinics: Facing
Higher Costs and Sicker Patients.” Family Planning
Perspectives, 23 (September/October), 198–203.
DSTDP — Division of STD Prevention. U.S. Department of
Health and Human Services, Public Health Service.
(1998). Sexually Transmitted Disease Surveillance,
Atlanta, GA: Centers for Disease Control and
Prevention.
Eng, Thomas & William Butler, eds. (1997). The Hidden
Epidemic: Confronting Sexually Transmitted Diseases.
Washington, DC: National Academy Press.
Friedman, Stanford B., et al. (1998). Comprehensive
Adolescent Health Care, 2nd ed. St. Louis, MO: Mosby.
Groseclose, Samuel, et al . (1999). “Estimated Incidence
and Prevalence of Genital Chlamydia trachomatis
Infections in the United States, 1996.” Sexually
Transmitted Diseases, 26 (6), 339–344.
Holmes, King K., et al. (1999). Sexually Transmitted
Diseases, 3rd ed. New York: McGraw-Hill.
Howell, M. René, et al. (1998). “Screening for Chlamydia
Trachomatis in Asymptomatic Women Attending Family
Planning Clinics: A Cost-Effectiveness Analysis of
Three Strategies.” Annals of Internal Medicine, 128 (15
February), 277–284.
Keat, Andrew. (1983). “Reiter’s Syndrome and Reactive
Arthritis in Perspective.” The New England Journal of
Medicine, 309 (26) (December 29), 1606–1614.
KFF — Kaiser Family Foundation. (1997, accessed 1999,
August 20). Doctors Don’t Ask, and Women Don’t
Tell: New Survey Finds STDs Are Rarely Discussed As
Part of Routine Gynecological Care: Press Release
[Online].
http://www.kff.org/content/archive/1313/experiencer
.html.
_____. (1998a, accessed 1999, July 12). The Kaiser Family
Foundation/Glamour 1998 Survey of Men and Women
on Sexually Transmitted Diseases: Press Release
[Online].
http://www.kff.org/archive/repro/survey/glamour199
8/glamour_rel.html.
_____. (1998b). Sexually Transmitted Diseases in America:
How Many Cases and at What Cost? Menlo Park, CA:
Kaiser Family Foundation and American Social Health
Association.
Landis, Sarah H., et al. (1992). “Cancer Statistics, 1999.”
CA — A Cancer Journal For Clinicians, 49
(January/February), 8–31.
Mertz, Gregory J., et al. (1992). “Risk Factors for the
Sexual Transmission of Genital Herpes.” Annals of
Internal Medicine, 116 (1 February), 197–202.
NCCDPHP — National Center for Chronic Disease Prevention
and Health Promotion.
(1999, accessed June 4). Fact Sheet: Risk of Ectopic
Pregnancy after Tubal Sterilization [Online].
http://www.cdc.gov/nccdphp/drh/mh_ectopic.htm.
NCHSTP — National Center for HIV, STD, & TB Prevention.
(1998a, accessed 1999, June 11). Critical Need to Pay
Attention to HIV Prevention for African Americans
[Online].
http://www.cdc.gov/nchstp/hiv_aids/pubs/facts/afra
m.htm.
_____. (1998b, accessed 1999, June 8). Critical Need to Pay
Attention to HIV Prevention for Women: Minority and
Young Women Bear Greatest Burden [Online].
http://www.cdc.gov/nchstp/hiv_aids/pubs/facts/wom
en.htm.
_____. (1998c, accessed 1999, June 11). The HIV/AIDS
Epidemic in the United States, 1997–1998 [Online].
http://www.cdc.gov/nchstp/hiv_aids/pubs/facts/hivre
pfs.htm.
_____. (1998d, accessed 1999, June 22). Impact of
HIV/AIDS on Hispanics in the United States [Online].
http://www.cdc.gov/nchstp/hiv_aids/pubs/facts/hispa
nic.pdf.
_____. (1998e, accessed 1999, June 22). Status of Perinatal
HIV Prevention [Online].
http://www.cdc.gov/nchstp/hiv_aids/pubs/facts/perin
atl.pdf.
_____. (1998f, accessed 1999, June 11). Trends in the
HIV/AIDS Epidemic [Online].
http://www.cdc.gov/nchstp/hiv_aids/stats/trends98.p
df.
_____. ([1999] accessed June 11). Tracking the Hidden
Epidemics: Trends in the STD Epidemics in the United
States [Online].
http://www.cdc.gov/nchstp/dstd/Stats_Trends/STD_Tr
ends.pdf.
OWH — Office of Women’s Health (1997, accessed 1999,
June 14). Sexually Transmitted Diseases [Online].
http://www.cdc.gov/od/owh/whstd.htm.
Ralph, S.G., et al. (1999). “Influence of Bacterial Vaginosis
on Conception and Miscarriage in the First Trimester:
Cohort Study.” British Medical Journal, 319 (7204)
(July 24), 220–223.
Sewankambo, Nelson, et al. (1997). “HIV-1 Infection
Associated with Abnormal Vaginal Flora Morphology
and Bacterial Vaginosis.” The Lancet, 350 (9077)
(August 23), 546–550.
Ventura, S.J., et al. (1998). “Births and Deaths: Preliminary
Data for 1997.” National Vital Statistics Report, 47(4).
Hyattsville, MD: National Center for Health Statistics.