Long‐acting Injectable Progestogens in Human Fertility Control

3 long-acting injectable progestogens given to fertile women for contraceptive purposes during a long period of time are discussed. 2418 women received im 1000 500 300 or 250 mg depomedroxyprogesterone acet ate (MPA) every 6 months or 150 mg every 3 months during 94300 months. 932 women received 150 mg chlormadinone acetate (CA) every 2 months or 250 mg every 2.5 or 3 months during 30000 months and 130 women received 200 mg norethisterone enanthate every 3 months during 2300 months. All of these drugs had very low failure rates that increased with prolonged use. The failure rates of 150 mg MPA and 250 mg CA were extremely low. These injectable progestogens appear to arrest the Graafian follicles just before the final maturation process. 150 mg MPA every 3 months or followed with 300 mg every 6 months and 250 mg CA every 2.5-3 months have high clinical efficacy when evaluated by the life-table method. Acceptability is limited by the tolerance to side effects. Proper instruction of potential users is fundamental to informing then on what they should expect. It is concluded that these progestogens have a valuable role as potent contraceptives in women with high obstetrical risk in those who have completed their family and in patients where effective intrauterine contraception is contraindicated.