Ethinyl estradiol and conjugated estrogens as postcoital contraceptives
G. W. Dixon, J. J. Schlesselman, H. W. Ory and R. P. Blye
Five study centers enrolled 1,311 women seeking postcoital contraception
methods. Ethinyl estradiol was administered at 5 mg/day and conjugated
estrogens at 30 mg/day for five consecutive days starting within 72 hours
of unprotected coitus. Eleven pregnancies occurred in the 976 women who had
a single unprotected coitus at midcycle. Based on published information, 69
pregnancies would have been expected if no contraceptives were used.
Although both treatments were effective in preventing pregnancy, ethinyl
estradiol seemed to be more effective. At the two centers alternately
prescribing both drugs, none of 137 women treated with ethinyl estradiol
became pregnant, while six of the 132 given conjugated estrogens became
pregnant. Women whose treatment commenced on the first postcoital day
seemed to have lower pregnancy rates than those whose medication was
delayed to the second or third postcoital day regardless of which drug was
used. Side effects were mainly limited to nausea that occurred in 70% and
vomiting that was experienced by 33% of all women treated.
