Contraceptive mechanism of IUDs.

The mode of action of intra-uterine devices (IUDs) continues to be a subject for speculation. It was Pincus (1964) who, on the basis of original experiments, first conceived the idea of hyperoestrogenism as the probable cause of the antifertility effect of IUDs. Various workers (Vorys, De Neef, Boutselis, Dettman, Scott, Stevens & Besch, 1964; Sammour, Iskander & Rifai, 1967; Bengtsson & Moawad, 1967) also considered the possibility of hormonal involvement in contraceptive action. The accidental finding of polycystic changes in the ovaries (S. K. Banerjee & K. Mukherjee, personal communication), associated with the use of IUDs in a group of women with severe menstrual trouble, who were undergoing an operation for sterilization, appeared to support the idea of hormonal involvement. The present work was undertaken to elucidate the mode of action of an IUD in preventing fertility. The devices were Lippes' loop and 'Antigon' and 350 women, aged 18 to 34 yr (parity\p=m-\oneto seven), who were known to have used an IUD for 3 years