Abstract

A nation-wide Rh prevention programme was started in Finland in 1969. Before that, a control series of approximately 1000 Rh-negative mothers giving birth to an Rh-positive child was collected to estimate the number of mothers with antibodies at either three, six, or nine months post partum. During the three-and-a-half year period altogether 14,980 Rh-negative patients were given 250 μg of anti-D immunoglobulin prepared from Finnish raw material in the Central Laboratory of the Dutch Red Cross. Out of those treated before the end of June 1972, 12,720 (97%) were tested four to six months post partum. Seventeen or 0·13% had detectable antibodies; in five of them the infant was ABO incompatible. The number of protected mothers with a subsequent Rh-positive infant was 1017; 10 had formed antibodies before the delivery of the second child.

The risk of primary immunization initiated during a single pregnancy was estimated to be 0·35%. In addition, there was approximately a 0·60% risk of forming antibodies by the next Rh-positive pregnancy.

The effect of prevention on the prevalence of haemolytic disease was calculated and compared with observed figures.