When the first oral contraceptives were introduced in the 1970s, they used relatively high doses of estrogen. Acting on the widely held view that lower doses of estrogen were safer, pharmaceutical companies gradually replaced the high dose pills with low dose versions. A new study of women who took high dose oral contraceptives, however, suggest that the concern over the high dose pills was misplaced.
Researchers at the Oxford Family Planning Association studied 17,032 women who visited family planning clinics in England and Scotland from 1968 to 1974.
Of the women how used high dose oral contraceptive, the death rate was actually 11 percent lower than for women who did not use high dose oral contraceptives. Due to the uncertainties in epidemic studies, that should not be read as implying that high dose contraceptives had a protective effect, but rather that their effect on the total death rate is not significant.
Which is not to say that high dose oral contraceptives might not contribute to some diseases. The study found that users of high dose oral contraceptives had much higher death rates from cervical cancer than non-users. But this was more than offset by a far lower risk of ovarian and other uterine cancers among users of high dose oral contraceptives.
The study confirmed that the major risk factor among the women in the study, both users and non-users of high dose oral contraceptives. Heavy smokers in the study had a death rate 100 percent higher than that of non-smokers.
Death rate low in former oral contraceptive users. Karla Gale, Reuters Health, July 18, 2003.