Diethylstilbestrol used as a “morning after” contraceptive
In the Netherlands, many women use a postcoital method of contraception in “emergency” situations.
Postcoital contraception started in the 1960’s with the administration of large doses of estrogens: 50 mg diethylstilbestrol for 5 days or 5 mg ethinylestradiol for 5 days.
In the eighties, a double-blind study compared the original hormonal therapy of 5 mg ethinylestradiol for 5 days with a combination pill containing just 0.1 mg in combination with 1 mg d1-norgestrel, of which two doses are give, the second 12 hours after the first. This method was as effective in preventing pregnancy as the original treatment with high estrogen dosage. Moreover, it resulted in women suffering less nausea and vomiting. One study from Hong Kong indicated that levonorgestrel without ethinylestradiol was as effective as the combination. Postcoital use of an intrauterine device to prevent pregnancy can be used as an alternative to the hormonal method. A recent development is the use of an antiprogestagen pill: 600 mg Mifepristone on day 27 of the cycle; side effects are minimal and the success rate is high. Mifepristone should be registered and made available in all countries for this indication.
Many women in the Netherlands depend on a postcoital contraceptive (PCC) method in situations of unprotected intercourse. The incidence rate for abortions and for adolescent pregnancies in the Netherlands is the lowest worldwide. Dutch society matter-of-factly accepts adolescent sexuality and provides formal and informal sex education and readily accessible contraceptive services. Emergency contraception should be administered within 72 hours after unprotected intercourse (e.g., rape or incest) or mechanical contraceptive failure. Administration of 5 mg ethinyl estradiol (EE) for 5 days as a PCC first occurred in the Netherlands in 1964, and PCC usage peaked at 55,000 in 1975. Side effects of EE include, in order of frequency, nausea, vomiting, tender breasts, and menorrhagia. Possible modes of action for EE are more rapid transport of fertilized ova through the oviduct and slowed maturation of the endometrium, resulting in suppressed implantation. The Yuzpe PCC method involves 4 tablets of a combined oral contraceptive (each tablet with 50 mcg EE + 250 mcg levonorgestrel) administered within 72 hours followed by 2 tablets 12 hours later. Side effects are similar to those of EE alone, as is the effectiveness rate. A dose of 0.75 mg levonorgestrel alone is as effective at preventing pregnancy as the Yuzpe regimen. Side effects are considerably less common with the levonorgestrel regimen than the Yuzpe regimen. For women who present more than 72 hours after and less than 7 days after unprotected intercourse or for those with contraindications to estrogen, a copper-releasing IUD can serve as a PCC. A postcoital IUD can cause serious complications for women with a sexually transmitted disease, however. Taking RU-486 during the luteal phase of the menstrual cycle greatly drops plasma levels of progesterone and estradiol. Postovulatory administration of an antiprogestogen is the best PCC method because of minimal side effects and a high success rate.
- Emergency contraception: a review, Contraception, NCBI PubMed PMID: 7956209, 1994 Aug.
- Featured image Michael Jasmund.