If Both Parents are a Positive, What is The child Blood Type?

Decoding Blood Types

Understanding blood types involves a bit of genetics.

There are four main blood types: A, B, AB, and O, which are determined by the presence or absence of antigens on red blood cells.

Type A has A antigens, type B has B antigens, AB has both, and O has neither.

In addition to these, there is another factor known as Rh factor, which can be either positive or negative.

How Blood Type is Inherited

The blood type of a child is determined by both parents.

Each parent passes one allele for blood type to their child.

The A and B alleles are co-dominant (meaning neither is dominant over the other), and the O allele is recessive.

When both parents are type A, there are three possible combinations for their children: AA (resulting in type A), AO (also resulting in type A), or OO (resulting in type O).

Positive Rh Factor

When it comes to Rh factor, the positive allele is dominant.

This means that a child will be Rh positive if at least one parent passes on the Rh positive allele.

If both parents are Rh positive, they can either be homozygous (Rh+/Rh+) or heterozygous (Rh+/Rh-).

If both parents are Rh+/Rh+, their children will be Rh positive.

If one or both parents are Rh+/Rh-, there’s a chance their children could be Rh negative.

However, since both parents in this scenario are Rh positive, the child is likely to be Rh positive as well.

Possible Blood Types

So, if both parents are A positive (A+), the possible blood types for their children could be A+ (AA or AO genotype with at least one Rh+ allele), A- (AA or AO genotype with both Rh- alleles), O+ (OO genotype with at least one Rh+ allele), or O- (OO genotype with both Rh- alleles).

It’s important to note that this is a simplification of the process.

Genetics can be more complex, with other factors potentially influencing blood type.

Genetics play an essential role in determining a child’s blood type. However, certain exceptions and additional factors can sometimes lead to unexpected outcomes. Always remember that this information is used as a general guideline, and the most accurate way to know your child’s blood type is through a medical blood test.

It’s also important to know that ABO and Rh blood types are not the only blood group systems present.

While they are the most commonly referred to in everyday conversation, there are actually 36 recognized human blood group systems by the International Society of Blood Transfusion as of 2020.

These various systems can also play a role in determining a child’s blood type and understanding potential compatibility issues.

However, they are not typically relevant for most people and are primarily of interest in certain clinical scenarios or for in-depth genetic study.

Now, let’s address some frequently asked questions:

Q1: Can a child have a different blood type than both parents?

A: Yes, it is possible. For example, parents with A and B blood types can have a child with either A, B, AB, or O blood types.

Q2: Is the Rh factor hereditary?

A: Yes, the Rh factor is inherited from both parents. The positive Rh factor is dominant over the negative Rh factor.

Q3: Can Rh negative parents have an Rh positive child?

A: No, Rh negative parents cannot have an Rh positive child. Both parents must have at least one Rh positive allele to have an Rh positive child.

Q4: Is it possible to change your blood type?

A: No, an individual cannot naturally change their blood type. It is genetically determined at birth.

Q5: Can blood type cause problems in pregnancy?

A: Yes, if an Rh negative woman is pregnant with an Rh positive child, it can potentially lead to Rh disease. However, it can be prevented with a medication called Rh immune globulin.

Q6: What are the other blood group systems?

A: Some of the other blood group systems include the Lewis system, the Kidd system, the Duffy system, among others. Each of these has unique antigens and antibodies that can influence blood reactions.

Q7: How often do blood type incompatibilities occur?

A: Blood type incompatibilities are not overly common, but they do occur. The most common scenario is Rh incompatibility, which can occur when an Rh-negative mother carries an Rh-positive baby. This situation can be managed effectively with medical intervention.

Q8: Can two O positive parents have an A or B blood type child?

A: Generally, no. If both parents are genuinely O positive, they can only have O positive or O negative children.

Q9: Can a child’s blood type change over time?

A: No, a child’s blood type does not change over time. The antigens that determine blood type are set at birth.

In conclusion, while the ABO and Rh blood type systems can give us a good idea of a child’s potential blood type based on their parents, it’s not always cut and dry. If you’re curious about your child’s blood type or have any concerns, it’s best to speak with a healthcare professional who can provide guidance and potentially perform a blood test for the most accurate results.


While it’s fascinating to predict a child’s blood type based on their parents’, it’s crucial to remember that actual blood typing through medical testing is the most accurate method to determine one’s blood type.

Knowing your blood type and Rh factor is important for situations like blood transfusions and pregnancy, where Rh incompatibility can potentially cause complications.

However, with modern medicine, these issues can be effectively managed.

In the end, regardless of blood type, every individual is unique and special in their own way.

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