Postcoital test abnormalities in relation to contraceptive use.

Abnormalities of cervical mucus can have a bearing on a woman's fertility. One means of detecting the presence of such abnormalities is the postcoital test (PCT). As part of a population-based case control study of risk factors for infertility, the reproductive, contraceptive, medical, and sexual histories of women seeking treatment for infertility who had abnormal PCT results were compared with those of fertile controls. A greater proportion of infertile women with an abnormal PCT had previously used a diaphragm than had control women (relative risk (RR) = 3.5, 95% CI = 1.1-11.3). The excess risk associated with use of a diaphragm was particularly high for women who had used one for longer than one year (RR = 7.3, 95% CI = 1.4-37.8), or within one year of attempting to conceive (RR = 5.5, 95% CT = 1.4-22.1). No increased risk was associated with the use of other barrier methods, oral contraceptives, or the intrauterine device.