HET RISICO VAN EEN ONBEDOELDE ZWANGERSCHAP NA EEN ONBESCHERMDE COITUS: BESCHOUWING BIJ DE HUIDIGE HORMONALE POSTCOITALE ANTICONCEPTIEMETHODEN

Tietze and Dixon have studied the average chance of getting pregnant after a single act of unprotected coitus. Tietze concluded that the chance lay between 2% and 4%. Dixon calculated that if the coitus occurred 1 day before ovulation the chance was 17.3%, gradually decreasing to zero toward the 9th day before and 6th day after ovulation. The commonly used hormonal postcoital contraceptive methods are 1) the morning-after pill consisting of 5 mg of ethinyl estradiol/day for 5 consecutive days, also called the 5x5 method; and 2) the 2x2 method comprised of taking 50 mg of ethinyl estradiol twice within an 12-hour interval. 3016 women were treated with the 5x5 method, and 17 pregnancies occurred with a failure rate of .6. According to Tietze the real number lay between 60 (2%) and 120 (4%) without treatment yielding a real rate of 14.2-28.4 for these 17 pregnancies. In a group of 1990 women with midcycle coitus, 11 pregnancies occurred yielding a failure rate of 4.9%, although according to Dixon 222 pregnancies were expected. 867 women were also treated with the 2x2 method, 93 women were excluded, and 18 pregnancies occurred, which corresponds to a failure rate of 2.1. According to Tietze the real number was 17 (2%) and 35 (4%), thus the 18 pregnancies yielded a real failure rate of 51.4 and 100. The 5x5 method was found effective in dogs and apes in the doses used, however, neither the method of administration, nor the indications were established for humans, thus at least in 90% of cases women are treated unnecessarily with an outright toxic medicine because of the exorbitantly high doses of synthetic estrogen. The 2x2 method has a high failure rate partly because of deficient instruction by doctors. The effectiveness of the 2x2 method is very meager, thus the medical ethical question arises of deceiving as many as 20,000 women who are prescribed this treatment every year.