EFFECTIVITY AND ACCEPTABILITY OF ORAL CONTRACEPTIVES CONTAINING NATURAL AND ARTIFICIAL ESTROGENS IN COMBINATION WITH A GESTAGEN

Abstract

With the purpose of investigating effectivity and acceptability of an oral contraceptive containing micronized natural estrogens (estradiol‐17β 4 mg + estriol 2 mg /norehisterone acetate 3 mg per tablet) versus a contraceptive containing artificial estrogen (ethinyl estradiol 50 μg/norethisterone acetate 3 mg per tablet), a controlled doubleblind investigation was performed in 111 young women. The investigation was designed for 12 cycles. The tablets were given consecutively for 3 weeks with 1 week's interruption. In the natural estrogen group 57 women completed 504 cycles, in the artificial estrogen group 54 women completed 510 cycles (Table I). No pregnancies occurred. There were highly significantly more terminations due to bleeding irregularities (p< 0.001), and highly significantly more spotting (p<0.001), breakthrough (p<0.001) and amenorrhea (p<0.00l) episodes in the natural estrogen group (Tables II and III). Bleeding irregularities on natural estrogens did not subside during the trial (Table IV). There were a few more psychiatric and CNS symptoms on natural estrogen (p<0.05), but other side effects did not differ between the two preparations (Table V). Blood pressure and weight did not vary significantly. Despite documented metabolic advantages, the natural estrogen tablet investigated was not found to be clinically acceptable for general usage because of the high incidence of bleeding irregularities. It is conceivable that a change of the estrogen/gestagen ratio, using a variable 3‐weck schedule, would reduce the number of bleeding irregularities.