A novel estrogen-free oral contraceptive pill for women: multicentre, double-blind, randomized controlled trial of mifepristone and progestogen-only pill (levonorgestrel). A andomized contraceptive trial comparing a daily progestogen with a combined oral contraceptive steroid. Randomised clinical trial to determine optimum initiation time of norgestrel-progestin only contraception in Eldoret Teaching Hospital, Kenya. A randomized, double-blind study of two combined and two progestogen-only oral contraceptives.
The acceptability and continuation rate of oral contraceptive steroids are limited by unpredictable bleeding and the fear of long-term risks such as breast cancer. By inhibiting ovulation and by altering the receptivity of the endometrium, antagonists of progesterone, such as mifepristone, could be developed as estrogen-free novel contraceptives.
                Multicentre, double-blind, randomized controlled trial comparing frequency of amenorrhoea (primary outcome), bleeding patterns, side effects and efficacy in women taking daily 5 mg mifepristone (n = 73) or 0.03 mg levonorgestrel (progestogen-only pill; POP, n = 23) for 24 weeks.
                More women were amenorrhoeic while taking mifepristone than POP (49 versus 0% P < 0.001), and fewer women bled or spotted for >5 days per month (4 versus 39% P < 0.001). Forty-eight percent of women who took mifepristone for 6 months had cystic glandular dilatation of the endometrium but none showed hyperplasia or atypia. There were no pregnancies in 356 months of exposure in women who used only mifepristone for contraception. Two pregnancies occurred in women taking mifepristone who were also using condoms for dual protection.
                Daily mifepristone (5 mg) is an effective oral contraceptive pill which has a better pattern of menstrual bleeding than an existing POP (levonorgestrel). nan In a randomised controlled trial to determine the optimum time of initiation of Ovrette, a progestin only oral contraceptive among postpartum women, who fully or nearly fully breast-fed their infants in the first six months, no difference was found between group 1 (initiating at six weeks postpartum) and group 2 (initiating the pill at return of menses or 6 months postpartum). There were no pregnancies in either group during the 18 month follow-up. There were no significant differences in the continuation rates between the two group. A randomized double-blind study of two combined oral contraceptives and two progestogen-only oral contraceptives was conducted using the same protocol at WHO Collaborating Centres for Clinical Research in Human Reproduction in Bombay and Ljubljana of the 518 women admitted to the trial, 123 received mestranol 50 micrograms + norethisterone 1mg (MES 50 + NET 1); 137 received ethinyl estradiol 30 micrograms + levonorgestrel 150 micrograms (EE 30 + LNG 150); 130 received norethisterone 350 micrograms/NET 350); and 128 received levonorgestrel 30 micrograms (LNG 30). At one year, between 52.6 and 61.0 percent of those recruited had discontinued oral contraceptive use for all reasons, and by two years, between 70.5 and 76.5 percent had discontinued the treatment. These rates did not differ between the four treatment groups. However, discontinuation rates for all medical reasons at one and two years, and at two years pregnancy rates and discontinuation rates for bleeding disturbances, were significantly lower in the EE/LNG preparation. The groups receiving the MES/NET, LNG and NET had similar pregnancy rates, discontinuation rates for all medical reasons and all bleeding disturbances. There were two ectopic pregnancies among the 22 pregnancies in the progestogen-only groups. Discontinuation because of headache, dizziness and other central nervous system symptoms were significantly more common in those receiving MES/NET compared to EE/LNG. In contrast, discontinuation for gastro-intestinal disturbances were significantly higher in the EE/LNG combined preparation. Bleeding disturbances in the first few cycles tended to be higher in NET than in the LNG group. The data suggest that greater consideration be given to the benefits and risks of including progestogen-only oral contraceptives in the family planning programmes of some countries.
Evidence is insufficient to compare progestin-only pills to each other or to combined oral contraceptives.