Some biological and biochemical effects (ie. KPI, cervical mucus, SHBG and ceruloplasmin) as well as serum ethynylestradiol and serum norgestrel, following the use of two oral contraceptives containing the same amount of norgestrel (dl-norgestrel 0.5 mg) and either 30 μg or 50 μg of ethynylestradiol were compared. There was no difference in the clinical features in either group of patients. There was a statistically significant difference in the levels of unconjugated ethynylestradiol but not in the other biochemical parameters studied.

Ovarian function was studied in ten women receiving a single intramuscular injection of 200 mg norethisterone oenanthate. Two of the ten women appeared to ovulate within 60 days of injection and a further four within 90 days. Follicular activity probably not followed by ovulation occurred in five subjects within 60 days of the injection and in a further subject within 90 days. Only one subject showed no evidence of follicular or luteal activity during the course of this study. There was wide variation in the rate at which the administered gestagen was metabolised and no correlation between the rate of metabolism of norethisterone and the return of ovarian function or the ponderal index, height or weight of the subjects.

Plasma norethisterone levels were measured in 15 women at varying times after the first injection of norethisterone oenanthate and in a group of 15 women who had received multiple injections of the gestagen. There was no difference between the two groups of women in respect of age, height and weight. There was a significant difference in the rate of metabolism of norethisterone oenanthate between the two groups and the results suggest that some accumulation of norethisterone occurs in women receiving multiple injections at intervals of ten or twelve weeks.

A 21-tablet oral contraceptive packet containing .5 mg dl-norgestrel and .03 mg estradiol was clinically tested in 1085 women of reproductive age for a total of 7323 cycles. There was 1 pregnancy which may have been due to incorrect tablet use. 98.2% of the cycles fell within a 28-day plus or minus 3-day pattern. 21% of the women had some breakthrough bleeding at some time, but it was confined to 1 cycle in 63% and not more than 2 cycles in 82%. The contraceptive is recommended for general use on the bases of how pregnancy rate, mean intermenstrual bleeding of .54 days per cycle, and the mean total bleeding of 4.87 days per cycle. The hypothesis that an effective combined oral contraceptive using norgestrel as the progestogen can employ as little as 30 mcg of estrogen is supported.