Blood Group Incompatibility

The most common and serious type of blood group incompatibility between mother and child can occur when the mother is Rhesus D negative and the fetus is Rhesus D positive. About 15% of pregnant women are Rhesus D negative, meaning they do not have the Rhesus D antigen on the surface of their red blood cells. Approximately 60% of Rhesus D negative pregnant women carry a Rhesus D positive fetus. They may develop red blood cell antibodies (Rhesus sensitization) that can have consequences for the next pregnancy if that fetus is also Rhesus positive.

Antibody Testing

Rhesus protection measures began in Iceland about half a century ago. These measures have involved regular antibody testing in pregnant women and the administration of anti-D immunoglobulin after birth to Rhesus D negative women who give birth to Rhesus D positive children.

Procedure

At the beginning of 2018, a new procedure for Rhesus protection was implemented. At the start of pregnancy, blood typing is performed on all women, and they are screened for red blood cell antibodies. At 25 weeks, all Rhesus D negative women are screened for red blood cell antibodies, and the Rhesus D type of the fetus is also identified. At 28 weeks, Rhesus D negative women who are carrying a Rhesus D positive fetus are offered an anti-Rhesus D antibody injection (Rhophylac® 1500 a.e.) to prevent sensitization of the mother. Rhesus D negative women carrying a Rhesus D negative fetus do not need the anti-Rhesus D antibody injection. After giving birth, women who received the Rhophylac® 1500 a.e. antibody injection during pregnancy at 28 weeks will receive another antibody injection. Blood samples from the umbilical cord will continue to be taken from all Rhesus D negative women. Screening for red blood cell antibodies at 36 weeks has been discontinued for all pregnant women.

Development of Diagnostic Methods

Work to develop the methods used to determine the Rh blood type of the fetus during pregnancy and to establish this system was primarily undertaken at Landspítali. The implementation was mainly supported by Hulda Hjartardóttir, Chief Physician of Obstetric Services at Landspítali, Anna Margrét Halldórsdóttir, Specialist at the Blood Bank, and Ragnheiður I. Bjarnadóttir, Chief Physician of Maternal Care at the Capital Area Health Care.