Estrogens and postcoital contraception

DES prescribed despite known teratogenic and potentially carcinogenic effects

1981 Study Abstract

The contraceptive effect of large doses of estrogens administered postcoitally is not fully understood, although numerous reports have described the use of a 4 to 6 day course of high dose oral diethylstilbestrol (DES), ethinyl estradiol, conjugated estrogens, and combinations of estrogen and progestogen.

Because estrogens are effective postovulatory rather than postcoital contraceptives, it is necessary to know the exact time of unprotected intercouse in relation to a woman’s menstrual cycle. Depending on the frequency and timing of intercouse, a 5-day course of postcoital estrogen, introduced within 72 hours, yields a pregancy rate of .03-.3%. Failures are usually due to inadequate doses of estrogen, errors in timing, or multiple exposures.

A lowering of basal body temperature after postovulatory administration of high doses of estrogen indicates successful intervention. Existence of various conditions such as hypertension and migraine contraindicate the use of postcoital estrogens. DES and possibly other estrogens are associated with teratogenic and potentially carcinogenic effects. 70 to 80% of women taking postcoital estrogens report side effects such as nausea, weight gain and headache.

No randomized studies have compared the efficacy, side effects, or safety of the available estrogens. The use of informed coinsent procedures is advised because of the potency of high dose estrogens.


  • Estrogens and postcoital contraception, Female patient, NCBI PubMed, PMID: 12278953, 1981 Jul.
  • Image credit your-life.

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