An estimated 30,000 to 33,000 people in the United States are living with hemophilia, based on treatment center data and CDC prevalence estimates. That number has grown substantially over recent decades, largely because of better diagnosis and dramatically improved treatment that has extended patients’ lives. Hemophilia remains rare, affecting roughly 1 in every 5,000 male births, but improved tracking has revealed it is more common than older estimates suggested.
Prevalence by Type
Hemophilia comes in two main forms. Hemophilia A, caused by low levels of a clotting protein called factor VIII, is by far the more common type. It occurs at a rate of about 12 cases per 100,000 males in the U.S., which translates to roughly 20,000 affected individuals. Hemophilia B, involving a different clotting protein (factor IX), is three to four times less common, occurring at about 3.7 cases per 100,000 males. That puts the hemophilia B population at around 6,000 to 7,000 people.
There is also a rarer form sometimes called hemophilia C, which involves a deficiency in yet another clotting factor. Unlike the other types, hemophilia C affects both men and women equally and occurs in about 1 in 100,000 people. It is typically milder and often goes undiagnosed until a person experiences unusual bleeding during surgery or after an injury.
How Common Is It at Birth?
In the U.S., about 1 in every 5,617 male births results in hemophilia A, and about 1 in every 19,283 male births results in hemophilia B. A large international meta-analysis using national registries found similar patterns globally: roughly 25 out of every 100,000 males born will have some form of hemophilia A, with about 10 of those cases being severe. For hemophilia B, about 5 per 100,000 male births have the condition, with only 1 to 2 of those being severe.
Hemophilia is an inherited condition carried on the X chromosome, which is why it overwhelmingly affects males. Women can be carriers and occasionally experience mild bleeding symptoms themselves, but full hemophilia in women is extremely rare. The condition occurs across all racial and ethnic groups at similar rates.
The Numbers Have Grown Over Time
The U.S. hemophilia population tracked through specialized treatment centers nearly doubled between 1990 and 2010, growing from about 17,200 patients to over 32,600. That growth reflects several overlapping trends. The hemophilia A population at treatment centers grew by 35% during that period (from roughly 9,800 to 13,300 patients), while the hemophilia B population grew by 66% (from about 2,500 to 4,200).
These increases don’t mean hemophilia became more common genetically. The biggest factors were improved survival thanks to modern clotting factor treatments, better diagnostic testing that catches milder cases, and expanded tracking systems. A 1972 government study estimated just 25,500 Americans had hemophilia A or B. Treatment center populations hit 20,000 in 1994, 25,000 by 2000, and 30,000 by 2008. Even today, treatment center data likely undercounts the true number because people with mild hemophilia may only visit a center every two or three years and can fall off the registry.
Severity Makes a Big Difference
Not everyone with hemophilia experiences it the same way. The condition is classified as mild, moderate, or severe based on how much functional clotting protein a person’s body produces. Someone with severe hemophilia makes less than 1% of the normal amount and can bleed spontaneously into joints and muscles without any obvious injury. Moderate hemophilia (1% to 5% of normal levels) leads to prolonged bleeding after injuries and occasional spontaneous bleeds. Mild hemophilia (5% to 40% of normal) may only cause problems during surgery, dental work, or significant trauma.
Roughly half to 60% of people with hemophilia A have the severe form, which is a higher proportion than many people expect for a genetic condition. Hemophilia B tends to have a slightly lower proportion of severe cases. The severity level is typically consistent within a family because it is determined by the specific genetic mutation involved.
Living With Hemophilia Today
Life expectancy for people with hemophilia has improved enormously. In the 1960s, the average lifespan was around 30 years. Today, with access to modern treatment, many people with hemophilia in the U.S. live into their 60s and 70s. The darkest chapter came in the 1980s and early 1990s, when contaminated blood products infected thousands of hemophilia patients with HIV and hepatitis C, causing a wave of premature deaths that temporarily reversed survival gains.
Current treatment involves replacing the missing clotting factor through regular infusions, either on a preventive schedule or in response to bleeding episodes. Newer therapies, including longer-lasting clotting factors and non-factor treatments that reduce the need for frequent infusions, have changed daily life considerably for many patients. Gene therapy, which aims to enable the body to produce its own clotting factor, has also recently become available for some adults with hemophilia, potentially reducing or eliminating the need for ongoing infusions.