Preliminary acceptability and reliability tests of the Dalkon Shield were done in 377 women over 17 months, amounting to 3,028 months of use. There was a 98% follow-up. The pregnancy rate of 4.7 and expulsion rate of 6.3 do not meet the claims described in initial trials by the developers of the device. Nevertheless, the Dalkon Shield seems to be an advance in intrauterine contraception since it has the advantages of a lower expulsion rate than the "first generation" inert intrauterine devices.