Risk Factors

Family History: When two or more immediate family members (parent, sibling, child) have PAH or a family member is known to have a PAH-causing gene mutation.

Obesity: Obesity is a risk factor for PH and can cause PH through several mechanisms. It is often associated with heart disease (high blood pressure, heart attacks, heart failure), which is a common cause of PH. It also increases the risk of blood clots in the legs (deep vein thrombosis, DVT) and in the lungs (pulmonary embolism, PE). Patients with PE are at risk of a type of PH called CTEPH. Obesity increases the risk of obstructive sleep apnea (OSA) and obesity-hypoventilation syndrome (OHS). Both OSA and OHS can cause PH. 

Gender: Idiopathic (IPAH) and familial PAH (FPAH) are at least 2.5 times more common in women than in men. Many connective-tissue diseases (scleroderma, lupus), which are important causes of PAH, are more common in women.

Pregnancy: Pregnancy is associated with a higher risk of developing PH, and being diagnosed with PH. Pregnancy increases the risk of blood clots in the legs (deep vein thrombosis, DVT) and in the lungs (pulmonary embolism, PE). Patients with PE are at risk of a type of PH called CTEPH. Pregnancy itself may also increase the risk of a woman developing PAH. Most commonly, a woman who already has PAH—whether diagnosed or undiagnosed—may experience more severe symptoms (than before they were pregnant) and more rapid disease progression. This is why PAH is sometimes diagnosed during pregnancy.

Altitude: The level of oxygen in air declines with increasing altitude, especially over 8,000 feet (over 2,400 meters). Living at a high altitude for years can make you more susceptible to PH. Travel at high altitudes can aggravate PH. 

Drugs & Toxins: Certain drugs are known to cause pulmonary arterial hypertension (PAH). These include drugs of abuse (methamphetamine, cocaine). Medical drugs can also cause PAH, including certain diet drugs, and chemotherapy for cancer. 

In some patients, there is no known cause for PH. These patients are diagnosed with idiopathic PAH.