This online Child Blood Type Calculator determines a baby’s blood types probabilities for the ABO and Rh systems based on the parents’ blood type.
Blood Type Genetics
A blood type (also known as a blood group) is a classification of blood, based on the presence or absence of antibodies in the blood plasma and inherited antigenic substances on the surface of red blood cells.
Blood types are inherited and represent contributions from both parents. The two most important (of many others) blood type systems are ABO and Rh.
ABO blood group system
There are four blood groups defined by the ABO system:
• A – has A antigens on the red blood cells and anti-B antibodies in the plasma;
• B – has B antigens and anti-A antibodies in the plasma;
• O – has no antigens, but both anti-A and anti-B antibodies in the plasma;
• AB – has both A and B antigens, but no antibodies in the plasma.
In genetics, blood type gene has two alleles, each allele has genotype A, B or O. The A and B are dominant, and O is recessive. So allele A combined with allele O is type A. Similarly, BO is type B, AA is type A, BB is type B, OO is type O, and AB is type AB.
The following table illustrates the blood types inherited by a baby from their parents. For example, assume that the parents blood types are A and B. That means that the parent with blood type A has alleles AA or AO. Similarly, the parent with blood type B has alleles BB or BO. So, combining genes of the two alleles from the both parents we get the following options: A (A+O), or B (O+B), or AB (A+B), or O (O+O).
To calculate the probability of each outcome is a bit tricky. Let’s take the last outcome from the above example. We know that type O is the result of combination of two alleles O. Assume that the parent with blood type A has alleles AA or AO with probability 50% each, and the parent with blood type B has alleles BB or BO also with probability 50% each. Then the probability that the parents have alleles AO and BO is 50%*50% = 25%. And finally only one in four combinations of AO and BO gives us the desired outcome O (O+O) with the probability 6.25%.
Our handy child blood type calculator can significantly facilitate these calculations.
Rh blood group system
The Rh system (Rh meaning Rhesus) is the second most significant blood-group system.
Red blood cells have another antigen (a protein that is found on the covering of the red blood cells), the Rh antigen which is also known as the D-Antigen, or RhD antigen, or Rh factor.
• If the Rh antigen is present, then the blood is RhD positive (+).
• If the Rh antigen is not present, then the blood is RhD negative (−).
Just as everyone inherits ABO genes, every person inherits one Rh factor gene from each parent. The Rh-positive gene is the dominant gene when paired with an Rh-negative gene. The following table illustrates the Rh factor inherited by a baby from their parents
The probability of any outcome can be easily found with the help of our online calculator.
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