O Positive Parents: What Blood Type Can the Child Have?

Few small facts spark as many family questions as blood type. If you are asking what blood type a child can have when the parents are O positive, or you are O positive yourself and wondering what your own parents might be, this guide gives you clear answers in plain English. You will find a simple chart for every common pairing, a short explanation of why blood types are inherited the way they are, and a gentle reminder at the end about what a blood type can and cannot tell a family.

For a companion chart covering A, B and AB parents, see parents blood type and child. For the bigger picture of raising children well, our hub on what makes a good parent is a good place to begin.

Blood Type Basics in Two Minutes

Your blood type is made of two separate parts. The first is the ABO group: A, B, AB or O. The second is the Rh factor: positive (+) or negative (−). So O positive means group O with a positive Rh factor.

1. Every person carries two ABO genes, one from the mother and one from the father.
2. The A and B genes are dominant. The O gene is recessive, so it only shows when a child receives O from both sides.
3. A person with group O therefore always carries two O genes (O and O).
4. A person with group A carries either A and A, or A and O. Group B is the same: B and B, or B and O.
5. Rh positive is dominant and Rh negative is recessive. A Rh positive person may carry a hidden negative gene.

If Both Parents Are O Positive: What Is the Child?

This is the most searched question, in forms like two O positive parents, o positive and o positive parents and if both parents are O positive what is the child. The answer is clear:

1. ABO group: the child will always be group O. Both parents can only pass on an O gene, so no A or B can appear.
2. Rh factor: the child is usually positive. If both parents carry a hidden negative gene, the child can be O negative, though this is less common.
3. So the possible results are O positive or O negative. A child of two O positive parents cannot be A, B or AB.

Chart: O Positive or O Negative Parents With Another Partner

The table below covers every pairing people ask about, such as o positive and a positive parents, o positive and b positive parents, o negative and a positive parents and so on. Read the first column for the parents, then the second for the possible ABO group of a child, and the third for the Rh factor.

Parents	Possible ABO types	Possible Rh
O+ and O+	O only	Positive (negative only if both parents carry the negative gene)
O+ and O−	O only	Positive or negative
O+ and A+	O or A	Positive (negative only if both parents carry the negative gene)
O+ and A−	O or A	Positive or negative
O+ and B+	O or B	Positive (negative only if both parents carry the negative gene)
O+ and B−	O or B	Positive or negative
O+ and AB+	A or B	Positive (negative only if both parents carry the negative gene)
O+ and AB−	A or B	Positive or negative
O− and O−	O only	Negative only
O− and A+	O or A	Positive or negative
O− and A−	O or A	Negative only
O− and B+	O or B	Positive or negative
O− and B−	O or B	Negative only
O− and AB+	A or B	Positive or negative
O− and AB−	A or B	Negative only

Notice that the ABO result depends only on the letters. The plus or minus changes only the Rh result.

Every O Positive Pairing Explained

Here are the most common combinations in short form, so you can find yours quickly.

1. O positive and O positive: child is O. Rh is positive or, if both carry the hidden gene, negative.
2. O positive and O negative: child is O. Rh can be positive or negative.
3. O positive and A positive (or A negative): child is O or A.
4. O positive and B positive (or B negative): child is O or B.
5. O positive and AB positive (or AB negative): child is A or B. A child of an O parent and an AB parent can never be O or AB.
6. O negative and A positive: child is O or A, and Rh can be positive or negative.
7. O negative and B positive: child is O or B, and Rh can be positive or negative.
8. O negative and AB positive: child is A or B, and Rh can be positive or negative.
9. O negative and O negative: child is O negative only.

If I Am O Positive, What Are My Parents?

Many people ask this the other way round: if I am O positive, what are my parents? Because group O needs an O gene from each side, both of your parents must carry at least one O gene. That gives these possibilities:

1. ABO of your parents: each parent is either group O (O and O), group A (A and O), or group B (B and O).
2. Neither parent can be AB, because an AB parent has no O gene to pass on.
3. Rh of your parents: at least one parent must be Rh positive, since you are positive. The other can be positive or negative.
4. Examples that fit: O and O, O and A, O and B, A and A, A and B, B and B. All can produce an O positive child, as long as each parent carries a hidden O gene.

This answers searches like if i have o positive blood what are my parents and parents of o positive blood type.

Why Rh Negative Babies Can Come From Rh Positive Parents

An Rh positive person can have two positive genes, or one positive and one negative. If two such parents each pass on their negative gene, the baby is Rh negative. So two positive parents can indeed have a negative child, and it is nothing unusual. We explain this in more detail in our chart for A, B and AB parents.

Quick Facts About Blood Type O

Group O is one of the most common blood groups in the world, and O negative is often called the universal donor for red blood cells because it can be given to people of any group in an emergency. O positive can be given to anyone who is Rh positive. People with group O can only receive group O blood themselves. Knowing your type is simply a good habit, in the same way that knowing your child’s date of birth or vaccination record is.

1. Write your blood type and each child’s type in a family health record once you have it confirmed.
2. Keep a copy of the lab report, not only a memory of the result.
3. Teach older children their type in a calm way, as a normal piece of health knowledge.

Worked Examples

1. Mother O positive, father O positive: every child is group O. If both carry a hidden negative gene, one child could be O negative while a sibling is O positive.
2. Mother O positive, father A positive: children may be O or A. Two siblings can have different groups with no cause for concern.
3. Mother O negative, father B positive: children may be O or B, and positive or negative.
4. Mother O positive, father AB positive: children will be A or B, never O or AB.

A Kind Reminder: Blood Type Is Not a Parentage Test

Blood type charts are a simple way to understand inheritance, but they are not proof of who a child’s parents are. Many different people share the same blood type, and a chart cannot confirm or deny a family relationship. A result that looks surprising may simply mean a hidden gene was involved, or that the blood type was recorded incorrectly.

Please do not let a chart become a reason for suspicion between husband and wife or within a family. Trust, respect and good manners are the foundation of a home. If you have a medical question about your own blood type or your child’s, a doctor or lab can confirm it properly.

Common Mistakes to Avoid

1. Assuming the plus or minus follows the same rule as the letters. They are separate.
2. Forgetting that group A and B parents may carry a hidden O gene.
3. Using a chart as proof in a family argument. It is a general guide only.
4. Mixing up your own type. If you are not sure, ask a doctor or check a lab report instead of guessing.

Frequently Asked Questions

If both parents are O positive, what is the child?

The child will be group O. The Rh factor is usually positive, but can be negative if both parents carry a hidden negative gene.

Can O positive parents have an A or B child?

No. Both parents can only pass on an O gene, so the child must be group O.

If I am O positive, can my father be AB?

No. An AB parent has no O gene, so a child of an AB parent cannot be group O.

Can O positive and O negative parents have a negative child?

Yes. If the O positive parent carries a hidden negative gene, the child can be O negative.

Blood type is an interesting piece of family science, but a warm home is built on kindness, patience and trust. For more guidance, visit our Family and Parenting section.