The female condom rarely breaks during use, but an efficacy study conducted in 1996-1998 indicates that slippage occurs in nearly one in 10 uses and women may be exposed to semen in up to one in five uses.1 Although a woman is most likely to be exposed if she and her partner experience mechanical problems with the condom, about half of exposures occur during uses in which couples do not have any problems. A separate set of analyses using the same data set shows that women also have an increased risk of being exposed to semen while using the female condom if they are in a shorter-term relationship, if there is a large disparity between the size of their vagina and the size of their partner's penis, and if intercourse is very active.2
The study was conducted among women recruited from family planning clinics and a university population in Birmingham, Alabama. Women were eligible if they were aged 21- 49, were using an effective nonbarrier method of birth control, were in a mutually monogamous relationship, had intercourse at least six times per month, were at low risk for sexually transmitted diseases, had a uterus and had used tampons. Women were trained to use the female condom, collect samples of vaginal fluid with swabs before and after intercourse, fill out a form documenting any problems during condom use and record details of intercourse in a coital log. The women returned used condoms, which were inspected to confirm use and detect tears. Researchers assessed semen exposure by comparing concentrations of prostate-specific antigen (PSA) in vaginal fluid collected before and after intercourse.
A total of 210 women participated in the training. The median age in this group was 27 years, and the median monthly income per household member was $600. Most of the women were white, were married and had completed college. Half had been in their current relationship for at least four years, and half had intercourse at least 12 times per month. None of the women had previously used the female condom.
Method-Related Problems and Semen Exposure
In analyses of 2,232 female condom uses by 175 participants who returned at least one condom, women reported either mechanical problems, which could lead to method failure, or acceptability problems, which could result in discontinuation, during 25% of uses. The most common mechanical problems were that the condom rode on the penis (7% of uses), the condom slipped out of the vagina (6%) and the outer ring slipped inside the vagina (3%). Condoms rarely broke (fewer than 1% of uses). The most common acceptability problems were that the woman or her partner felt pain or discomfort (6% and 4% of uses, respectively) and the condom made noise (3%). Overall, problems were more common during the first five uses than during subsequent uses; however, mechanical or acceptability problems still occurred in nearly one in 10 uses of the 20th condom.
The researchers studied semen exposure by examining data on 1,485 female condom uses that took place 24 hours or more after the previous act of intercourse, and for which PSA results were available; they used two criteria of exposure, to take into account random variations in PSA levels. According to these analyses, women were exposed to semen during 7-21% of uses, depending on the criterion used for exposure. In most cases, the quantity of semen a woman was exposed to was minute.3 The rate of exposure was highest among women who experienced mechanical problems with the device (22-35% of uses), markedly lower among those reporting acceptability problems (9-20%) and lower still among those who had no problems (5-19%). Nonetheless, at least 53% of exposures occurred during uses for which women did not report any problems.
Results of a multivariate analysis indicated that regardless of how exposure was defined, a woman had a significantly elevated risk of being exposed to semen if her partner's penis entered to the side of the condom, if semen leaked onto her, if the outer ring slipped into her vagina and if the condom broke. A woman's odds of exposure decreased slightly as she and her partner used more female condoms.
Noting that semen exposure, a novel measure of condom failure, has advantages over traditional measures, the researchers nevertheless point out that further studies are needed "to determine which semen exposure levels, as measured by PSA, predict the risk for pregnancy and [sexually transmitted disease] and to compare the female condom with the male condom."
Partner Characteristics and Semen Exposure
Characteristics of couples and intercourse associated with semen exposure were assessed in a multivariate analysis of 1,149 female condom uses by 100 women for which both coital log data and PSA data were available. These results showed that the odds of exposure to semen were about doubled if women reported that intercourse was more active than usual (odds ratio, 1.7) or if they had been in the relationship for less than two years (2.4). Women also had elevated odds of exposure (2.7) if they had a relatively large vagina (i.e., diaphragm size, 75-80 mm, as measured by a nurse practitioner at the beginning of the study) and their partner's penis was below the median size (as measured by the women, according to instructions they received at enrollment).
Further analyses revealed that women with a large vagina were at increased risk of having their partner's penis enter to the side of the condom (odds ratio, 3.0) and of having the condom's outer ring slip into their vagina (3.5). Women living in households in which the monthly income was more than $900 per member were substantially less likely than women living in households with lower incomes to be exposed (0.3). In this analysis, a woman's odds of exposure to semen did not change as couples became more experienced using the female condom.
Commenting on the findings, the research-ers note that even though the female condom may not offer perfect protection, it provides complete protection against semen in most uses. They add that couples with a large mismatch between vaginal size and penis size and couples having very active intercourse might want to consider methods of protection other than the female condom.--S. London
1. Macaluso M et al., Efficacy of the female condom as a barrier to semen during intercourse, American Journal of Epidemiology, 2003, 157(4):289-297.
2. Lawson ML et al., Partner characteristics, intensity of the intercourse, and semen exposure during use of the female condom, American Journal of Epidemiology, 2003, 157(4):282-288.
3. Macaluso M et al., Macaluso et al. respond to "condom effectiveness and prostate-specific antigen," American Journal of Epidemiology, 2003, 157(4):301-302.