• Fifty-four percent of women who have abortions had used a contraceptive method (usually the condom or the pill) during the month they became pregnant. Among those women, 76% of pill users and 49% of condom users report having used their method inconsistently, while 13% of pill users and 14% of condom users report correct use.[Jones RK, Darroch JE and Henshaw SK, Contraceptive use among U.S. women having abortions in 2000–2001, Perspectives on Sexual and Reproductive Health, 2002, 34(6):294–303; Alan Guttmacher Institute, July 2008, http://www.guttmacher.org/pubs/fb_induced_abortion.html]
Can STDs/STIs be prevented?
Yes, STIs can be prevented. Avoid all sexual activity if you are single or be faithful to one uninfected partner for life. This is the only way to avoid the risk of an infection.
There are also a number of ways to reduce the risk — but NOT eliminate the risk — of infection. The fewer people you have sex with, the lower your risk of getting STIs. Correct and consistent condom use can also reduce (but not eliminate) your risk of getting most STIs.
Consistent and Correct condom use (100%) during vaginal sex reduces your risk for:
HIV by 85% [18-22]
Gonorrhea by about 50% [18,25-28]
Chlamydia by about 50% [18,25-28]
Herpes by about 50% [18,27-28]
Syphilis by about 50% [16,18,25-27]
HPV by 50% or less [18,22-24]
Few studies have been done to see whether condoms reduce the risk of STIs, including HIV, during oral sex or anal sex.
Waiting to have sex until you are in a faithful, lifelong relationship (such as marriage) is the only certain way to avoid being infected sexually.
[This is an excerpt from "Sex, Condoms, and STDs: What We Now Know", a monograph by The Medical Institute.]
"Safer Sex" is not nearly safe enough…
As a medical and educational organization, The Medical Institute for Sexual Health emphasizes a principle fundamental to moderm medical practice. That priciple is "informed consent" which, for this monograph, is more accurately termed "informed decision making".
This section of the monograph provides a quick reference of the currently available research conducted on condom effectiveness.
To read the entire monograph, in order to "gain a complete appreciation for the impact and importance of this research", visit www.medinstitute.org.
Summary of Key Findings
- Consistent (always) condom use is defined as 100 percent condom use during all sex acts indefinitely.
- To provide any reasonable hope of avoiding most STD infections, condoms must be used 100 percent of the time by individuals outside of lifelong mutually faithful monogamous relationships (usually found in marriage).
- Even 100 percent condom use does not eliminate the risk of any STD including HIV.
- Condoms slip or break on average 1.6 percent to 3.6 percent of the time even when used 100 percent of the time, potentially exposing sexual partners to STD infection. [34, 35, 46, 72]
- "Protection" is the term often applied to condom use. This can be misleading because condoms only reduce the risk of infection. They do not "protect" 100 percent of the time from any STD.
- Condoms do not prevent the transmission of STDs from lesions outside the areas covered by, or "protected" by, condoms. 
- All studies of condom use are done for a limited period of time – from a few acts of sex to 2 or 3 years of activity. Single individuals who are sexually active usually continue sexual activity year after year. With an increasing number of sexual partners and sex acts comes an increasing risk of STD infection, even with 100 percent condom use. (See discussion in the section "The impact of Cumulative Effectiveness".)
- One hundred percent use of condoms for many years is so uncommon that it is almost a purely theoretical concept excpet for very few, very meticulous individuals. Even among adults who knew that their partner had HIV, only 56 percent used condoms every time (and the median follow up was only 24 months). 
- There is no evidence of any risk reduction for sexual transmission of human papillomavirus infection (HPV) even with 100 percent condom use. There is some evidence that condom use "might afford some reduction in risk of HPV associated disease including genital warts in men and cervical neoplasia in women". Neoplasia means cervical precancer or cervical cancer.  (The scientific explanation for this phenomenon is beyond the scope of this paper.)
- Current evidence does not show that Trichomonas vaginalis sexual transmission is reduced even with 100 percent condom use. [1, 72]
- Syphilis transmission is reduced by 29 percent to 50 percent with 100 percent condom use. Although the data about syphilis transmission is limited, current data show that even with 100 percent condom use, there remains a 50 percent to 71 percent relative risk of syphilis infection. [1, 9] (See the definition of relative risk in the section "Scientific Language and the Discussion of Condom Effectiveness".)
- Gonorrhea transmission is reduced by approximately 50 percent with 100 percent condom use. Although the data about gonorrhea transmission is limited, current evidence shows that even with 100 percent condom use there remains a 50 percent relative risk of gonorrhea infection. [ 1, 9, 72]
- Chlamydia transmission is reduced by approximately 50 percent with 100 percent condom use. Although the data about chlamydia transmission is limited, current evidence shows that even with 100 percent condom use, there remains a 50 percent relative risk of chlamydia infection. [ 1, 9]
- Genital herpes sexual transmission: A recent stu
dy showed that with 25 percent or more condom use, there was risk reduction for females but not for males.  Expanded data by the same author, as yet unpublished but presented at a national conference, show risk reduction of approximately 40 percent for both males and females when condoms were used for 65 percent or more of sex acts. Although the data about herpes transmission is limited, current evidence shows that even with condom use, there remains a 60 percent relative risk of herpes infection. 
- HIV sexual transmission is reduced by approximately 85 percent with 100 percent condom use, leaving approximately 15 percent relative risk — even with 100 percent condom use. [26, 72] Inconsistent condom use affords significantly less risk reduction. As discussed later in this monograph, 85 percent risk reduction rates were found in an ideal situation for condoms reducing the risk of HIV transmission.
- For the approximately 20 other STDs, not enough data exist to say whether or not condoms offer any risk reduction from sexual transmission.
- Approximately 25 percent of adolescents report alcohol or drug use during their most recent sexual behavior, compromising their ability to use condoms correctly or at all. 
- There are certain groups of people who are more susceptible to some STDs. These groups include those already infected with an STD. For example, the presence of another STD, particularly an ulcerative disease, can significantly increase the risk of acquiring (or transmitting) HIV if an individual is exposed to a sexual partner who is HIV positive. [30, 38]
- Females are more susceptible to many STDs than are males because they have a larger surface susceptible to infection…In addition, adolescent females are at higher risk of certain STDs than are adult women, due to anatomical differences of the uterine cervix associated with age.  These factors decrease dondom effectiveness due to the increased susceptibility of the individual. In addition, women suffer more of the severe complications of STDs than men do (e.g., cervical cancer, infertility).
- Most people infected with an STD do not know it. For example, a study of adolescent females who had one or more of 6 STDs studied (genital herpes, chlamydia, gonorrhea, syphilis, hepatitis B, trichomoniasis) showed that 87 percent had NO symptoms. 
- Individuals and their partners who do not think they have an STD may not be highly motivated to use condoms consistently.
[Sex, Condoms, and STDs: What We Now Know, monograph by The Medical Institute]