The effectiveness of<unk> s, as with most other forms of contraception, can be assessed two ways: method effectiveness and actual effectiveness. The method effectiveness is the proportion of couples correctly and consistently using the method who do not become pregnant. Actual effectiveness is the proportion of couples who intended that method as their sole form of birth control and do not become pregnant; it includes couples who sometimes use the method incorrectly, or sometimes not at all. Rates are generally presented for the first year of use. Most commonly the Pearl Index is used to calculate effectiveness rates, but some studies use decrement tables. Contraceptive Technology reports that the method failure rate of the Prentif<unk>  with spermicide is 9% per year for nulliparous women (women who have never given birth), and 26% per year for parous women (who have given birth). The actual pregnancy rates among Prentif users vary depending on the population being studied, with yearly rates of 11% to 32% being reported. An FDA-mandated study reported failure rates: Method rate 6.4% (vs. 4.6% for the diaphragm); Overall rate 17.4% (vs. 16.7% for the diaphragm). Little data is available on the effectiveness of the Oves<unk>  and FemCap. The Oves manufacturer cites one small study of 17 users. The FemCap website does not cite any data on the current version of the FemCap, but lists data for an older version which is no longer approved by the FDA. The effectiveness trial of Lea's Shield was too small to determine method effectiveness. The actual pregnancy rate was 15% per year. Of the women in the trial, 85% were parous (had given birth). The study authors estimate that for nulliparous women (those who have never given birth) the pregnancy rate in typical use may be lower, around 5% per year. Compared to other barrier methods In the 1920s, Marie Stopes considered the<unk>  to be the best method of contraception available. Among barrier methods it provides the least intervention of a barrier surface between the penis and vagina resulting in natural contact between them. Except for the Fem-Cap, it also leaves exposed all the vaginal wall so that the hormones, etc. in the seminal fluid of the man can be better absorbed by the woman. The condom does not allow any absorption and the diaphragm exposes less area. However the condom does significantly reduce the likelihood of transmission of STDs. The diaphragm is inserted painlessly. It does not stretch the vagina, nor does it interfere with internal muscle movements during sex, as it is too high up in the vagina. The tip of the penis might touch the condom depending on the position and the size of the penis. Note that what Stopes calls the "Dutch<unk> " is today known as the "diaphragm". A partial objection to this claim is that most women do not know how to voluntarily control these muscles, and that some size diaphragms do not stretch the vagina that much, especially if they are smaller in size The<unk>  can be worn for a significantly longer period of time than the diaphragm. It can be inserted several hours before intercourse and used successfully even if a woman's partner is drunk, etc. Stopes concludes in favor of the<unk>  and "condemns" the diaphragm "for general use"
Cervical cap
Pinard horn
Breast shell
Clinic
Phrygian cap 
Tubex 
Glabella
Vaginal cuff