Many things can increase a child's risk for asthma. Some of these are not within your control; others you can control.
Personal and family history
Gender. Among children, boys have asthma more often than girls.
Race.Asthma is more common in black children than in white children.2
Bronchial tubes that overreact. Children who inherit a tendency of the bronchial tubes (which carry air to the lungs) to overreact often develop asthma.
A history of allergies, including food allergies. Children who have an allergy are more likely than other children to develop asthma. Most children with asthma have allergic rhinitis, atopic dermatitis, or both. Studies show that 40 to 50 out of 100 children who have 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.3
Secondhand cigarette smoke. Children who are around secondhand cigarette smoke are at increased risk for developing asthma.5 If children already have the disease, secondhand smoke increases the severity of their symptoms.
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.6
Cigarette smoking during pregnancy. Women who smoke during pregnancy increase the risk of wheezing in their babies. Babies whose mothers smoked during pregnancy also have worse lung function than babies whose mothers did not smoke.5