Parental Blood Types
Select ABO and Rh types for each parent to display potential child blood types using Mendelian inheritance assumptions.
Parent 1
Parent 2
Possible child blood types
How to Use This Calculator
Select parental phenotypes
Choose ABO and Rh factor for each parent as reported on blood typing records.
Review potential child outcomes
The calculator lists all possible phenotypes assuming typical Mendelian inheritance and no rare variants.
Understand limitations
Actual probabilities depend on parental genotypes (e.g., AO vs AA). Rare alleles or weak antigen expression may alter results.
Formula
ABO inheritance follows Mendelian alleles: A and B dominant over O, with AB co-dominance.
Rh(D) inheritance is autosomal dominant: presence of the D antigen yields Rh positivity.
Child phenotype = combination of one allele from each parent for ABO and Rh systems.
Full Description
ABO blood types are determined by alleles A, B, and O, while Rh(D) status depends on expression of the D antigen. Parents contribute one allele from each system to their child. This calculator enumerates all possible phenotypes compatible with the parental types. It is intended for educational use and does not account for rare genetic variants, cis-AB, subgroup antigens, or weak D typing nuances.
Frequently Asked Questions
Can two type O parents have a type AB child?
No. Two O parents carry only O alleles, so their children can only be type O.
Why is Rh-positive more common?
The D antigen is dominant. A single D allele (Dd) produces an Rh-positive phenotype, increasing prevalence.
Does this predict exact probabilities?
No. It lists possible outcomes. Precise probabilities require knowledge of genotype (e.g., AO vs AA) or family history.
How does this relate to transfusion compatibility?
Recipients must receive compatible ABO and Rh blood. Type O negative is the universal donor; AB positive is the universal recipient.