Alloimmunized Fetal Blood Group Genotyping (Allo-FBGG)

This test is publicly funded for Ontario residents who are pregnant and have one or more of these red blood cell antibodies:

• anti-D
• anti-C
• anti-c
• anti-E
• anti-K (Kell) 

Who should not have this test?

Allo-FBGG is NOT recommended if you:

• Have antibodies other than anti-D, anti-C, anti-c, anti-E or anti-K (Kell)
• Started the pregnancy with more than one baby and one was lost
• Have anti-D antibodies that have been confirmed to be passive (for anti-D only)
• Have a known RHD variant or weak D blood type (for anti-D only)

The timing of when the tests is done depends on the antibody:

• Anti-D, anti-C, anti-c and anti-E are tested from 16 weeks of pregnancy
• Anti-K (Kell) is tested from 20 weeks of pregnancy

This test uses a sample of your blood. During pregnancy, small pieces of genetic material from the placenta circulate in your blood. The lab looks at this material to determine if your baby has the blood group antigen that your antibody reacts to.

Your blood can be drawn at a community lab and sent to Mount Sinai Hospital for testing. Use our map to find a lab near you. 

Results are usually ready in about 10 business days and are sent to your health-care provider.

What if the test cannot give a result?

Sometimes the test cannot give a result. Another blood sample may be requested to repeat the test, or it may be recommended to treat your pregnancy as if your baby has the antigen and provide closer monitoring.

Learn more about Fetal Blood Type Results & Next Steps

After delivery, a small sample of umbilical cord blood will be collected to confirm your baby’s antigen status. These results may be used to guide newborn care and for laboratory quality checks.