“…Although it wasoncegenerally accepted that Rh-immunization during pregnancy was rare (Nevanlinna & Vaino, 1962), it had been reported that the frequency of this phenomenon was not negligible (Hartmann & Brendemoen, 1953). Later studies have shown that the frequency of Rh-immunization during pregnancy is of the order of 1-3 per cent (Bishop & Krieger, 1970;Bowman, 1971;Chown, 1968;Dambrosio, 1971; Dudok de Witt et al, 1968). A clinical investigation using 250 pg anti-D for prophylaxis of Rh-immunization was started in 1968 at the Clinic of Obstetrics and Gynaecology at Vaxjo in order to find answers to the following questions: ( a ) How many Rh-negative women delivered of Rh-positive babies have antibodies at parturition?…”