Many factors may increase the risk of a child developing asthma. Some of these are not within your control; others you can control.

Asthma risk factors that you cannot control

• Gender. Among children, boys have asthma more often than girls.
• Race. Asthma is more common in black children than in white children.⁵
• Inherited tendency (genetic predisposition) to overreaction of the bronchial tubes. Children who inherit a tendency of the bronchial tubes (which carry air to the lungs) to overreact often develop asthma.
• A history of allergies. Children with an allergy are more likely than other children to develop asthma. Most children with asthma have allergic rhinitis, atopic dermatitis, or both. Studies indicate that 40% to 50% of children with atopic dermatitis develop asthma. Having atopic dermatitis as a child may also increase the risk of a person having more severe and persistent asthma as an adult.⁶
• A family history of allergies and asthma. Children who have an allergy and asthma usually have a family history of allergies or asthma.
• Respiratory syncytial virus (RSV) and wheezing at a young age. Early infection with respiratory syncytial virus (RSV) that causes a lower respiratory infection is a risk factor for wheezing.⁷ Young children who wheeze have a greater risk of developing asthma than children who do not wheeze.

Asthma risk factors that you can control

You may be able to change some factors to reduce your child's risk of developing asthma or of making the condition worse.

• Cigarette smoking. Children who smoke are more likely to develop asthma when they become teenagers. A large study found that children who smoked at least 300 cigarettes in a year were almost 4 times more likely to get asthma.⁸
• Cigarette smoking during pregnancy. Women who smoke during pregnancy increase the risk of wheezing (a symptom of asthma) in their babies. Babies whose mothers smoked during pregnancy also have worse lung function than babies whose mothers did not smoke.⁹
• Exposure to secondhand cigarette smoke. Children who are exposed to secondhand cigarette smoke are at increased risk for developing asthma.⁹ If children already have the disease, exposure to secondhand smoke increases the severity of their symptoms.
• Obesity. Studies have found an association between obesity in children and a higher-than-average asthma prevalence. However, the reason for the association is unclear. Experts don't know whether one condition contributes to the other or whether some unknown mechanism contributes to both.⁵ Also, symptoms caused by obesity are sometimes thought to be asthma symptoms.
• Dust mites. Exposure to dust mites may increase your child's risk for developing asthma.⁹
• Cockroaches. In one study, children who had a high level of cockroach droppings in their home were 4 times more likely to have a new diagnosis of asthma than children whose homes have a low level.⁹