A negative is an uncommon blood type, but it doesn’t meet the medical definition of “rare.” About 8% of blood donors have A negative blood, making it one of the less common of the eight major blood types. It’s not as scarce as AB negative (1%) or B negative (3%), but it’s far less prevalent than the two most common types: O positive (36%) and A positive (28%).
Where A Negative Ranks Among Blood Types
Of the eight standard blood types in the ABO and Rh system, A negative falls right in the middle of the distribution. NHS Blood Donation data breaks it down like this:
- O positive: 36%
- A positive: 28%
- O negative: 14%
- A negative: 8%
- B positive: 8%
- B negative: 3%
- AB positive: 2%
- AB negative: 1%
So A negative ties with B positive as the fourth most common blood type. It’s uncommon, yes, but roughly 1 in 12 people carry it.
What Doctors Actually Mean by “Rare”
In transfusion medicine, a blood type is classified as rare when it occurs in fewer than 1 in 1,000 people. That threshold applies to unusual combinations where someone is missing a common antigen found on nearly everyone’s red blood cells. A negative, at 8%, is nowhere close to that cutoff. The types most people think of as rare, like AB negative at 1%, are still technically “uncommon” rather than medically rare. True rare blood types involve antigen patterns most people have never heard of and affect tiny fractions of the population.
Ethnicity Changes the Numbers Significantly
That 8% figure reflects predominantly white populations. A negative blood is considerably less common in other ethnic groups. Among African Americans, only about 2% have A negative blood. The rate is the same, around 2%, for Latin American populations. In Asian populations, A negative drops to just 0.5%, or about 1 in 200 people. If you’re of Asian descent and have A negative blood, your type genuinely is unusual within your community, which can make finding compatible donors more difficult in regions where the local donor pool reflects that demographic.
Who A Negative Donors Can Help
A negative blood is compatible with four blood types: A negative, A positive, AB negative, and AB positive. That means A negative donors can supply blood to roughly 39% of the population. For A negative recipients, the options are more limited. You can only receive red blood cells from A negative or O negative donors.
This asymmetry is part of why A negative supply matters. A negative individuals depend on a relatively small donor pool (about 22% of donors combined between A negative and O negative), while their donations serve a much wider group. When blood banks run low, A negative is one of the types that gets squeezed from both directions: demand from multiple recipient types and a limited number of eligible donors.
Why Blood Banks Frequently Need A Negative
The American Red Cross has specifically flagged A negative as a type that runs short during blood supply crises. During a recent severe shortage, when the national blood supply dropped by about 35%, A negative was called out alongside O and B negative as especially needed. The core problem is math: 8% of donors supply blood for a much larger share of potential recipients, so even small dips in donation rates create shortages quickly.
There’s also an indirect benefit to maintaining strong A negative reserves. In emergencies where a patient’s blood type is unknown, hospitals typically reach for O negative, the universal donor type. When O negative stocks run low, hospitals sometimes have to give Rh-positive blood to patients who may turn out to be Rh negative, which carries a risk of triggering an immune response. One study found that about 26% of known Rh-negative patients who received Rh-positive blood during a shortage developed antibodies against it. Keeping less common Rh-negative types like A negative well stocked helps reduce pressure on the O negative supply and lowers that risk for everyone.
What Being Rh Negative Means for Pregnancy
The “negative” in A negative refers to the Rh factor, a protein on the surface of red blood cells. If you’re Rh negative and your baby inherits Rh-positive blood from the other parent, your immune system can treat the baby’s blood cells as foreign and produce antibodies against them. This is called Rh incompatibility, and it’s the reason Rh-negative blood types get extra attention during pregnancy.
The risk during a first pregnancy is relatively low, about 1%. But once your body creates those antibodies, they persist. In subsequent pregnancies with an Rh-positive baby, those antibodies can cross the placenta and attack the baby’s red blood cells, causing a condition called hemolytic disease of the newborn. In severe cases, this leads to dangerous anemia, brain damage from high bilirubin levels, or stillbirth. A survey of women who had already developed these antibodies found that roughly 70% of their pregnancies were affected to some degree.
The good news is that this is almost entirely preventable. Since the early 1970s, Rh-negative mothers have received an injection of anti-D immunoglobulin, which stops the immune system from forming those antibodies in the first place. Guidelines in the UK, Australia, and many other countries recommend a routine injection around 28 weeks of pregnancy and another within 72 hours of delivery. This regimen reduces the risk of developing antibodies from about 1% to roughly 0.2%. If you’re A negative and pregnant or planning to become pregnant, your provider will test for the Rh factor early and build this into your care plan automatically.
How A Negative Blood Is Inherited
You end up with A negative blood through a specific combination of genes from both parents. The “A” part comes from inheriting at least one A gene for the ABO blood group. The “negative” part means you inherited two copies of a deletion in the gene responsible for the Rh-D protein, one from each parent. Both parents must carry at least one copy of this deletion. About 17% of the population is homozygous for this deletion, meaning both their copies are the negative version, making them Rh negative. If only one parent is Rh negative and the other carries one copy of the deletion (heterozygous), there’s a 50% chance any given child will be Rh negative.
This is why A negative blood can appear in families with no obvious history of it. Both parents might be A positive or even O positive but carry the recessive Rh-negative gene without knowing it.