They don't work 100% of the time:
Effectiveness
In preventing pregnancy
See also: Comparison of birth control methods#Effectiveness of various methods
The effectiveness of condoms, as of most forms of contraception, can be assessed two ways. Perfect use or method effectiveness rates only include people who use condoms properly and consistently. Actual use, or typical use effectiveness rates are of all condom users, including those who use condoms improperly, inconsistently, or both. Rates are generally presented for the first year of use.[3] Most commonly the Pearl Index is used to calculate effectiveness rates, but some studies use decrement tables.[99]
The typical use pregnancy rate among condom users varies depending on the population being studied, ranging from 10–18% per year.[100] The perfect use pregnancy rate of condoms is 2% per year.[3] Condoms may be combined with other forms of contraception (such as spermicide) for greater protection.[90]
Several factors account for typical use effectiveness being lower than perfect use effectiveness:
mistakes on the part of those providing instructions on how to use the method
mistakes on the part of the user
conscious user non-compliance with instructions.
For instance, someone might be given incorrect information on what lubricants are safe to use with condoms, mistakenly put the condom on improperly, or simply not bother to use a condom.
In preventing STDs
A giant "condom" on the Obelisk of Buenos Aires, Argentina, part of an awareness campaign for the 2005 World AIDS DaySee also: Safe sex
Condoms are widely recommended for the prevention of sexually transmitted diseases (STDs). They have been shown to be effective in reducing infection rates in both men and women. While not perfect, the condom is effective at reducing the transmission of HIV, genital herpes, genital warts, syphilis, chlamydia, gonorrhea, and other diseases.[101]
According to a 2000 report by the National Institutes of Health, correct and consistent use of latex condoms reduces the risk of HIV/AIDS transmission by approximately 85% relative to risk when unprotected, putting the seroconversion rate (infection rate) at 0.9 per 100 person-years with condom, down from 6.7 per 100 person-years. The same review also found condom use significantly reduces the risk of gonorrhea for men.[102]
A 2006 study reports that proper condom use decreases the risk of transmission for human papillomavirus by approximately 70%.[103] Another study in the same year found consistent condom use was effective at reducing transmission of herpes simplex virus-2 also known as genital herpes, in both men and women.[104]
Although a condom is effective in limiting exposure, some disease transmission may occur even with a condom. Infectious areas of the genitals, especially when symptoms are present, may not be covered by a condom, and as a result, some diseases can be transmitted by direct contact.[105] The primary effectiveness issue with using condoms to prevent STDs, however, is inconsistent use.[80]
Condoms may also be useful in treating potentially precancerous cervical changes. Exposure to human papillomavirus,[106] even in individuals already infected with the virus, appears to increase the risk of precancerous changes. The use of condoms helps promote regression of these changes. In addition, researchers in the UK suggest that a hormone in semen can aggravate existing cervical cancer, condom use during sex can prevent exposure to the hormone.[107]
Causes of failure
The Wikibook Sexual Health has a page on the topic of
Barrier Birth Control and Spermicide
Condoms may slip off the penis after ejaculation,[108] break due to improper application or physical damage (such as tears caused when opening the package), or break or slip due to latex degradation (typically from usage past the expiration date, improper storage, or exposure to oils). The rate of breakage is between 0.4% and 2.3%, while the rate of slippage is between 0.6% and 1.3%.[102] Even if no breakage or slippage is observed, 1–2% of women will test positive for semen residue after intercourse with a condom.[109][110] "Double bagging," using two condoms at once, also increases the risk of condom failure.[111][112]
Different modes of condom failure result in different levels of semen exposure. If a failure occurs during application, the damaged condom may be disposed of and a new condom applied before intercourse begins - such failures generally pose no risk to the user.[113] One study found that semen exposure from a broken condom was about half that of unprotected intercourse; semen exposure from a slipped condom was about one-fifth that of unprotected intercourse.[114]
Standard condoms will fit almost any penis, although many condom manufacturers offer "snug" or "magnum" sizes. Some manufacturers also offer custom sized-to-fit condoms, with claims that they are more reliable and offer improved sensation/comfort.[115][69][116] Some studies have associated larger penises and smaller condoms with increased breakage and decreased slippage rates (and vice versa), but other studies have been inconclusive.[81]
Experienced condom users are significantly less likely to have a condom slip or break compared to first-time users, although users who experience one slippage or breakage are more likely to suffer a second such failure.[117] An article in Population Reports suggests that education on condom use reduces behaviors that increase the risk of breakage and slippage.[118] A Family Health International publication also offers the view that education can reduce the risk of breakage and slippage, but emphasizes that more research needs to be done to determine all of the causes of breakage and slippage.[81]
Among people who intend condoms to be their form of birth control, pregnancy may occur when the user has sex without a condom. The person may have run out of condoms, or be traveling and not have a condom with them, or simply dislike the feel of condoms and decide to "take a chance." This type of behavior is the primary cause of typical use failure (as opposed to method or perfect use failure).[119]
Another possible cause of condom failure is sabotage. One motive is to have a child against a partner's wishes or consent.[120] Some commercial sex workers from Nigeria reported clients sabotaging condoms in retaliation for being coerced into condom use.[121] Placing pinholes in the tip of the condom is believed to significantly impact their effectiveness.[110][122]
Prevalence
The prevalence of condom use varies greatly between countries. Most surveys of contraceptive use are among married women, or women in informal unions. Japan has the highest rate of condom usage in the world: in that country, condoms account for almost 80% of contraceptive use by married women. On average, in developed countries, condoms are the most popular method of birth control: 28% of married contraceptive users rely on condoms. In the average less-developed country, condoms are less common: only 6-8% of married contraceptive users choose condoms.[123]
Condom use for disease prevention also varies. Among gay men in the United States, one survey found that 35% had used two condoms at the same time, a practice called "double bagging".[124] (While intended to provide extra protection, double bagging actually increases the risk of condom failure.)
en.wikipedia.org
No, I had to pay for two abortions because I liked barebacking in the 70's and the gals told me they were on the pill.
And most people, like Bristol and Levi, are as smart as you. Rubbers aren't high tech devices. So a trip to PP before hand wouldn't have mattered. It would probably have encouraged them in thinking rubbers meant they had no worries. |
