Low dosage progestagen as an oral contraceptive: a clinical study.

A low dose of an oral progestagen (norethindrone 0.35 mg. daily) was used as a contraceptive agent in a group of 70 women. The average period of use was 16.7 months; it was over two years in 21 subjects. Eight patients withdrew from the trial because of excessive or irregular bleeding. The incidence of side effects was lower than with the combined type of contraceptive preparations. Of the six pregnancies that occurred, only two could be attributed to failure of the method.