B negative blood type
One of the rarest types: under 2% of Americans are B negative.
1.5%
about 1 in 67 people · #7 of 8
What B negative means
B negative red cells carry the B antigen but not Rh D. The plasma contains anti-A.
B negative patients can receive only B− and O− red cells, and both are scarce, so blood services actively recruit B negative donors.
The combination is rare simply because it needs two less-common traits at once: the B allele and two copies of the Rh-negative allele.
Plasma
B- plasma can be given to O+, O-, B+, B-. A B- patient can receive plasma from B+, B-, AB+, AB-. Plasma rules run opposite to red cells because plasma carries antibodies, not antigens.
Best way to donate
Whole blood or double red cells. B negative red cells help B−, B+, AB− and AB+ patients, and with so few donors every unit counts.
Genetics
ABO genotype BB or BO; Rh genotype dd. Want to know what blood type your children could have? Use the blood type calculator.
Pregnancy
Rh negative: anti-D (RhoGAM) is usually offered if the baby could be Rh positive. Read the Rh factor guide.
B negative blood type FAQs
Who can B negative donate to?
B−, B+, AB− and AB+ patients.
Who can B negative receive from?
B− and O− red cells.
Does B negative blood cause health problems?
No. Having B negative blood is not a disease. The practical issues are finding compatible blood if you need a transfusion and Rh care in pregnancy.