The exact number of people who have pulmonary hypertension (PH) isn’t known. Group 1 pulmonary arterial hypertension (PAH) without a known cause is rare. PH that occurs with another disease or condition is more common.

Anyone can develop PH. However, PAH that has no known cause affects about two to three times as many women as men. PH usually develops between the ages of 20 and 60, but it can occur at any age.

People who are at increased risk for PH include:

* Those who

have a family history of the condition.
* Those who have certain diseases or conditions, such as heart and lung diseases, liver disease, HIV infection, or blood clots in the pulmonary arteries. (For more information on diseases, conditions, and factors that can lead to PH, see “Types of Pulmonary Hypertension.”)
* Those who use certain diet medicines or street drugs (such as cocaine).