Oral contraceptive use in relation to smoking

Background. Use of OC simultaneous with smoking in older women remains a concern for prescribing physicians, in light of current guidelines for OC use and evidence from recent studies about risks and benefits of different OC agents. It is useful to look at prevalence of OC use simultaneously with smoking after age of 35, as an indication of the effectiveness of these guidelines. Methods. Survey of OC use in relation to smoking on a representative sample of 1138 urban women aged 40-54, from Geneva, Switzerland. History of exposure to both OC and smoking is analyzed up to the age of 40. Results. Seventy-six percent of women had ever used OC, and 49% had ever smoked by age 40. Fifty-four percent of women reported OC exposure simultaneous to smoking at some time, and simultaneous exposure accounted for 48% of woman-years of use. But simultaneous use decreased with age, such that simultaneous users during age 36-40 accounted for 37% of OC users during that age period, and for only 13% of all ever OC users. Similarly, woman-years of OC use simultaneous with smoking fell after age 25, and woman-years during age 36-40 accounted for 36% of woman-years during that age period, such that only 5% of woman-years of OC use overall. Conclusions. OC use simultaneous with smoking after age 35 is not typical. Results suggest that a physician today may prescribe a type of OC that fits a young woman's current risk profile, confident of being able to change OC use or smoking by the time the woman enters an older risk profile. Prescribing OC to a young smoker does not generally lead to simultaneous exposure at a later age.