Oral contraceptive use: association with frequency of hospitalization and chronic disease risk indicators.

A questionnaire was mailed to 97,364 married women, aged 26--50, resident in Greater Boston in 1970, requesting information on lifetime oral contraceptive (OC) use, reproductive history, education, and hospitalization experience in 1969; 65,843 women responded. In 1973 a second questionnaire was mailed to 37,292 of these women, including all OC users and an equal number of non-users matched on age, parity, education, and town of residence. This questionnaire related to use of OCs, other female hormones, and the menopause. OC use was most strongly related to age, with a sixfold increase in use from the oldest women (of whom 10 per cent had used OCs at some time) to the youngest. Use was directly related to education and mobility and inversely related to parity. Reasons for beginning and ceasing use differed for women of different ages and educational attainment. Thus, use of OCs varies with social and reproductive characteristics that are risk indicators for many diseases. OC use was associated with increased risk of hospitalization for thromboembolic disease (risk ratio = 1.5, 95 per cent confidence limits 1.2, 3.2) and for mental illness, hyperthyroidism, hypertension, and cancer of the cervix. OC users were hospitalized for many non-life threatening conditions 20 to 40 per cent more frequently than were non-users.