Question 1

How do you predict a baby's blood type from parents?

Accepted Answer

A baby's blood type is determined by inheriting one ABO gene from each parent. Each parent contributes either an A, B, or O allele. The child's blood type results from the combination of these alleles. For example, if one parent has type A (genotype AO) and the other has type B (genotype BO), the child could be A, B, AB, or O. Use our calculator to see all possible blood types and their probabilities based on parent blood types.

Question 2

What blood types can two O parents have?

Accepted Answer

Two parents with type O blood can only have a baby with type O blood (100% certainty). This is because type O individuals have the OO genotype and can only pass the O allele to their children. Since the baby receives O from each parent, the result is always OO (type O). For Rh factor, two O- parents will have an O- baby (100%), while two O+ parents can have O+ or O- babies.

Question 3

Can two A blood type parents have a B baby?

Accepted Answer

No, two parents with type A blood cannot have a type B baby. Type A parents (genotype AA or AO) can only pass A or O alleles to their children. Possible offspring blood types are A (most likely) or O. The only way to have a type B child is if at least one parent has a B allele (type B or AB blood). If two type A parents have a type B child, it indicates non-paternity or very rare genetic anomalies.

Question 4

How is the Rh factor inherited?

Accepted Answer

The Rh factor is inherited independently from ABO blood type. Rh positive (+) is dominant over Rh negative (-). Two Rh- parents will always have Rh- children (100%). One Rh+ and one Rh- parent can have either Rh+ or Rh- children. Two Rh+ parents usually have Rh+ children, but can have Rh- children if both parents carry the recessive Rh- gene (heterozygous). Rh status is important for pregnancy management and blood transfusions.

Question 5

What does ABO blood type inheritance mean?

Accepted Answer

ABO blood type inheritance follows Mendelian genetics. Each person has two ABO alleles (one from each parent). A and B alleles are codominant (both expressed if present), while O is recessive (only expressed with OO genotype). Possible genotypes: AA or AO = Type A, BB or BO = Type B, AB = Type AB, OO = Type O. Parents with hidden O alleles (AO or BO genotypes) can have type O children even if neither parent is type O.

Question 6

Can two parents with positive blood types have a negative baby?

Accepted Answer

Yes, two Rh+ parents can have an Rh- baby if both parents are heterozygous (carry one + and one - allele). For example, if both parents are +/- genotype, there's a 25% chance their baby will be -/- (Rh negative). However, two Rh- parents (both -/-) can only have Rh- children. Rh+ is dominant, so only one + allele is needed for a positive blood type.

Question 7

What is the rarest blood type combination?

Accepted Answer

AB- (AB negative) is the rarest blood type, found in less than 1% of the population. It occurs when a child inherits an A allele from one parent and a B allele from the other, plus Rh- from both parents. Other rare types include B- (1.5% of population) and AB+ (3.4%). O+ is the most common at 37% of the population, followed by A+ at 36%.

Question 8

Why is blood type important during pregnancy?

Accepted Answer

Blood type is crucial during pregnancy for several reasons: Rh incompatibility (Rh- mother with Rh+ baby) can cause hemolytic disease of the newborn if not treated with RhoGAM. ABO incompatibility (usually O mother with A or B baby) can cause mild jaundice. Blood type determines eligibility for certain prenatal screenings. Knowledge of parental blood types helps predict baby's type for medical preparedness. All pregnant women have blood type tested early in pregnancy.

Question 9

Can blood type change over time?

Accepted Answer

No, your blood type is determined at conception and remains the same throughout life. The only exceptions are extremely rare cases: bone marrow or stem cell transplantation can change blood type to match the donor's type, and very rarely, some diseases affecting bone marrow may alter blood type. Blood type is determined by genetics and coded in every cell with DNA. If blood type appears to change, it's usually due to testing error or misidentification.

Question 10

How accurate is this blood type calculator?

Accepted Answer

This calculator is 100% accurate for predicting possible blood types based on Mendelian genetics and established inheritance patterns. However, it cannot predict which specific blood type a child will have - only the possible options and their probabilities. Actual blood type is determined at conception and confirmed through blood testing after birth. The calculator assumes standard genetics; extremely rare genetic mutations or chimerism are not accounted for.

Blood Type Calculator - Baby Blood Type Predictor & Inheritance Chart

Possible Blood Types

Blood Type Inheritance Patterns

Example: A+ and B+ Parents

How Blood Type Inheritance Works

Genetic Inheritance Rules

Understanding ABO Blood Groups

Sources & References

Blood Type Inheritance Examples

Parents: O × O

Child's Possible Types:

Parents: A × B

Child's Possible Types:

Parents: AB × O

Child's Possible Types:

Rh Factor: - × -

Child's Rh Factor:

Frequently Asked Questions

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