The ovulation method was evaluated by the World Health Organization in a five-country study. Women who successfully completed three monthly cycles of teaching were enrolled in a 13-cycle efficacy study. There was a 3.1% probability of pregnancy in 1 year for the small proportion of couples who used the method perfectly and 86.4% probability of pregnancy for the rest (22). A review of 15 national surveys from developing countries estimated a 12-month gross failure rate of 24 pregnancies per 100 (23).
Conceptions resulting from intercourse remote from the time of ovulation more often lead to spontaneous abortion than conceptions from midcycle intercourse (24). Malformations are not more common (18).
Condoms In the 1700s, condoms made of animal intestine were used by the aristocracy of Europe, but condoms were not widely available until the vulcanization of rubber in the 1840s (1). Modern condoms usually are made of latex rubber, although condoms made from animal intestine are still sold and are preferred by some who feel they afford better sensation. New condoms made from nonlatex materials—such as polyurethane or synthetic elastomers that are thin, odorless, transparent, and transmit body heat—are available. Although the nonlatex condoms may break more easily than the latex varieties, substantial numbers of study participants preferred them and would recommend them to others (25).
The risk of condom breakage is about 3% and is related to friction (26). Use of water-based lubricants may reduce the risk of breakage. Petroleum-based products such as mineral oil must be avoided because even brief exposure to them markedly reduces the strength of condoms (27).
Gonorrhea, ureaplasma, and pelvic inﬂammatory disease (PID) and its sequel (tubal infertility) are reduced with consistent use of barrier methods (28–30). Tested in vitro, Chlamydia trachomatis, herpes virus type 2, HIV, and hepatitis B did not penetrate latex condoms but did cross through condoms made from animal intestine (31). Follow-up of sexual partners of HIV-infected individuals showed that condom use provides considerable protection (32). Consistent condom use provides more protection than inconsistent use (33). In one study, couples who use condoms 0% to 50% of the time had an HIV seroconversion rate of 20.8 per 100 couple years, whereas those who used condoms 100% of the time had a conversion rate of only 2.3 per 100 couple years (34). Nonoxynol-9 should not be used with condoms for HIV protection because it is associated with genital lesions. Nonoxynol-9 does not add to the protection afforded by condoms alone (35).
Condoms offer protection from cervical neoplasia (36). The relative risk for invasive cervical cancer was 0.4 when those who used condoms or diaphragms were compared with those who never used them (37). The presumed mechanism of protection is reduced transmission of human papillomavirus (HPV).
Latex allergy could lead to life-threatening anaphylaxis in either partner from latex condoms. Nonlatex condoms of polyurethane and Tactylon should be offered to couples who have a history suggestive of latex allergy.