“…Interpretation of this result is problematic, given the criteria for selection into the sample, for reasons given above for the combined pill. Implants and Injectables (Table 9) Evidence about the efficacy of long-acting progestogens in the form of an injectable or an implant comes only from clinical trials, since the drugs are not approved for Mishell et al, 1968 Depo-Provera 150 mg 100 0.Oc 59% aged 21-30 24.0c (90-day) Howard et al, 1982 Norigest 200 mg 383 0.0c 6.5" Britain (56-day) WHO, 1983 Depo-Provera 150 mg 1,587 0. (Sivin et al, 1983;Sivin, 1987a).…”