[Prevention of maternal RhD isoimmunization with anti-D gamma isoimmunization]

To report our experience in preventing RhD maternal isoimmunization by using anti-D gamma globulin among Rh-negative women.

Between 1982 and 1995, immunologic and hematologic data were collected from all Rh-negative women seen at Mexico's National Perinatology Institute. Women at risk of Rh isoimmunization were given a prophylactic dose of 150 micrograms of anti-D gamma globulin.

A total of 4,857 Rh-negative women were seen during the study period (4.85% of the total population of women seen at the Institute), 629 (13.0%) of whom developed RhD isoimmunization; 542 (86.2%) of these women were already isoimmunized when first seen at our Institute. Twenty-two women (3.5%) developed isoimmunization even after receiving a proper dose of anti-D gamma globulin. Prophylaxis was given to 2,605 women (53.6%); 2,039 received a single dose, and 475 two doses. Prophylaxis failed in 22 cases; four were women with multiple pregnancy and 18 developed obstetric pathologic conditions.

The use of anti-D gamma globulin resulted in a reduction of maternal Rh isoimmunization to less than one case per 1,000 women. Failures to prevent isoimmunization were associated to additional obstetric conditions and to lack of adherence to prevention guidelines.