Latex was first used for condoms around 1850 and remains the most common material despite significant disadvantages. An estimated 7 percent of the general population (and up to 25 percent of health care workers) are allergic to latex. Other disadvantages include short shelf life, vulnerability to failure if used with oil-based lubricants, problems with correct usage, inhibition of sensation, and relatively low conduction of heat compared with other materials. Loose-fitting polyurethane condoms were developed as an alternative for latex-sensitive persons and may be easier to use and provide greater sensitivity than latex. Steiner and colleagues studied the effectiveness and acceptability of polyurethane condoms compared with latex condoms in a randomized controlled trial.
They recruited 900 healthy couples from 10 U.S. sites. Study participants had to be in a stable, mutually monogamous relationship, have at least six episodes of sexual intercourse per month, and be willing to use only the type of condom provided during every act of vaginal intercourse. Women were required to have a history of regular menses when not using hormonal contraception and could not have had any recent abnormal Papanicolaou smear findings other than inflammation, infection, or atypical squamous cells of undetermined significance. Women could not have evidence of infertility, genital tract disease, or sexually transmitted disease, including human immunodeficiency virus infection. If women had used an injectable contraceptive, the last injection must have been six months before the study, and they must have had at least two normal menses since the last injection; if they had used an oral contraceptive pill, they must have had at least one normal menses since discontinuing the pill.
The couples were randomly assigned to receive latex or polyurethane condoms. All participants received comprehensive instructions on condom use, and women were tested for pregnancy at the beginning of the study and at weeks 4, 10, 16, and 22. Women were interviewed by telephone at week 26, and both partners were interviewed at the clinic at week 30. In addition, all participants completed questionnaires at week 4 and were asked to report all adverse effects or suspected pregnancies.
The two groups were similar in all important characteristics. The rates of discontinuation and reasons for doing so were similar. The probability of pregnancy occurring in six months of typical use was 9.0 percent for polyurethane condoms (95 percent confidence interval [CI], 5.9 to 12.2) and 5.4 percent for latex condoms (95 percent CI, 2.9 to 7.8). Polyurethane condoms were more likely to break (3.8 compared with 1.2 percent) or slip (4.9 compared with 2.0 percent). Polyurethane condoms were associated with less local irritation, and men and women rated them significantly higher than latex condoms for comfort and sensitivity. Although users of polyurethane condoms reported lower confidence in this product at the beginning of the study, they were more likely than users of the latex condom to recommend the product to a friend. However, this difference had disappeared by the final week of the study. The groups rated both types of condom equal in ease of use.
The authors conclude that polyurethane condoms were not as effective as latex in preventing pregnancy, but that both offered pregnancy protection in the range of other barrier methods of contraception. Persons who find latex condoms unacceptable may prefer polyurethane condoms because of increased sensitivity and a lower rate of local irritation. For persons with latex sensitivity, polyurethane condoms provide a good alternative.