ArticlesMortality in relation to oral contraceptive use and cigarette smoking
Introduction
Patterns of mortality in the Oxford Family Planning Association (Oxford FPA) contraceptive investigation have been reported previously,1, 2, 3, 4 most recently in 1989,4 by which time 238 women had died. We present our findings until Dec 31, 2000, based on analysis of 889 deaths. We examined mortality associated with oral contraceptive use and cigarette smoking. In our view, this issue is of public health importance because both use of such contraceptives and smoking are common in women of childbearing age and, arguably, at least as much negative publicity exists about oral contraceptive use as about smoking. Our results should enable direct comparisons between the two exposures that were analysed with information from the same database.
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Study population
Methods used in the study have been described elsewhere.1 17 032 women were recruited from 17 family planning clinics in England and Scotland between Jan 1, 1968 and Dec 31, 1974. To be eligible, the women had to be aged 25–39 years, married, white, British, willing to cooperate, and have been a user of either the contraceptive pill for at least 5 months, or a diaphragm or an intrauterine device for at least 5 months without previous pill use. At recruitment, women were asked about their date
Preliminary assessment of data
We first compared mortality from oral contraceptive use and that from smoking in women who were active in the study (ie, under individual yearly follow-up) with that in the whole cohort to the end of 2000. The active cohort analysis was based on woman-years of observation from recruitment until (a) emigration (802 women), death (384), or age 45 being reached with less than 8 years of pill use (6041); (b) loss to follow-up or withdrawal of cooperation (1208); or (c) the end of the individual
Discussion
The present analysis is based on a much larger number of deaths (889) than those in our previous reports,1, 2, 3, 4 and considers mortality from smoking and from oral contraceptive use. Although many researchers have described the effects of smoking on mortality in women,6 we are unaware of any who have compared the effects of smoking with those of oral contraceptive use on the basis of data derived from the same study. Furthermore, as far as we are aware, the findings presented here are the
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