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Predict possible baby blood types from two parents’ ABO and Rh results. See every compatible child phenotype (A+, O−, AB+, etc.), teaching probabilities, and Rh inheritance notes—for expecting parents and students. Not for legal paternity or transfusion orders.
Last updated: June 4, 2026
Baby's Possible Blood Types
Explanation:
With parents A+ and B+, possible child blood types: A+, A-, B+, B-, AB+, AB-, O+, O-.
Blood Type Probabilities:
Rh Factor Inheritance:
Both parents Rh+: baby can be Rh+ (most likely) or Rh− if both parents carry a hidden Rh− allele
Genetic Inheritance:
One ABO allele from each parent. A and B codominant; O recessive (needs OO for type O phenotype).
Blood Type Genetics:
A+ × B+
A+, A-, B+, B-, AB+, AB-, O+, O-
Up to 8 phenotypes
O+ × O+
O+, O-
Both parents Rh+: baby can be Rh+ (most likely) or Rh− if both parents carry a hidden Rh− allele
AB+ × O+
A+, A-, B+, B-
No type O or AB child
| Parents | Child ABO types | Teaching probability | Notes |
|---|---|---|---|
| O × O | O only | 100% O | Cannot be A, B, or AB |
| A × A | A or O | 75% A, 25% O (if parents carry O) | Hidden O allele common |
| B × B | B or O | 75% B, 25% O | Same as A × A pattern |
| A × B | A, B, AB, or O | 25% each ABO type | Most combinations possible |
| AB × O | A or B only | 50% A, 50% B | No AB or O child |
| AB × AB | A, B, or AB | No type O | 50% AB if both parents AB |
| Reported type | Common genotype | Red cell antigens |
|---|---|---|
| Type A | AA or AO | A antigen on RBCs |
| Type B | BB or BO | B antigen on RBCs |
| Type AB | AB only | Both A and B antigens |
| Type O | OO only | Neither A nor B |
| Rh+ | D+ (dominant) | Rh(D) protein present |
| Rh− | dd (recessive) | No Rh(D) protein |
Emergency and blood-bank rules are more detailed than this table. For education only.
| Recipient | Can receive RBC from | Label |
|---|---|---|
| O− | O− only | Universal donor (RBCs) |
| O+ | O± | — |
| A− | O−, A− | — |
| A+ | O±, A± | — |
| B− | O−, B− | — |
| B+ | O±, B± | — |
| AB− | O−, A−, B−, AB− | — |
| AB+ | All ABO/Rh combinations | Universal recipient |
O+
~37%
A+
~36%
B+
~9%
AB+
~3%
O−
~7%
A−
~6%
B−
~2%
AB−
<1% (rarest)
When an Rh− woman carries an Rh+ fetus, sensitization can affect future Rh+ pregnancies. Modern care includes anti-D prophylaxis (RhoGAM) per schedule—this calculator only lists possible fetal Rh types (e.g., A− × B− parents → Rh− child only: A-, B-, AB-, O-).
Education only. Confirm your baby’s type with hospital testing. Do not use this tool for paternity disputes, transfusion decisions, or Rh prophylaxis timing—follow your obstetric team.
For expecting parents, genetics students, and childbirth educators
Suggested hashtags: #BloodType #Genetics #Pregnancy #Calculator