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Some children are more likely than others to get asthma. This is because they have certain risk factors.

Risk factors are things that increase a person's chance of getting an illness.

Having parents who smoke increases a child's risk of getting asthma. There's a risk from:

• Smoking during pregnancy. If a woman smokes when she's pregnant the chance that her baby will get asthma increases by more than 50 percent.¹
• Smoking around children. Children whose parents smoke are more likely to get asthma than children whose parents don't smoke.²

There's a link between asthma and other allergic conditions, such as eczema and hay fever. About 1 in 3 children with eczema will go on to get asthma.³

Some studies have found a link between being treated with antibiotics as a baby and getting asthma in later life.^{3 4} But it's hard to know whether antibiotic use in babies could actually cause asthma. It might just be that when babies become wheezy, doctors may think they have a chest infection and treat them with antibiotics. So the children in the study might have been given antibiotics for a chest infection, when they really had asthma all along.

This information is for educational use only, and is not a substitute for prompt professional medical advice. Readers should always consult a physician or other professional for advice and treatment. ©BMJ Publishing Group Limited 2008. All rights reserved.