Ask An Expert: Inheriting Asthma

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Ask An Expert: Inheriting Asthma

Question:

I am a pregnant asthmatic. What are the chances my baby will develop the same disease? Is it hereditary?

Answer:

While asthma is hereditary, the chances your child will develop asthma depend on environmental exposures as well. It isn't as easy as estimating the chances that your child will have your eye or hair color. To give you some ballpark numbers, if one parent has asthma, the child has around a 25 percent chance of developing asthma. This could be higher or lower depending on whether an environmental factor triggers the development of asthma. If both parents have asthma, your child could have a 50 percent chance of developing asthma. In general, a strong family history of the allergic conditions asthma, hay fever, eczema or hives increases your child's risk for asthma. Because the incidence of childhood asthma is increasing, research has focused on the environmental exposures that trigger the development of asthma. Whether or not early infections increase or decrease your child's risk for asthma is not clear. Early group daycare under the age of 4 months seems to increase the risk slightly, but having other siblings in the home seems to decrease the risk. There is also mixed evidence about pets. Some studies show an increased risk for allergies and asthma with early exposure to animals, while other studies show that having a dog or cat decreases the risk. Although you can't avoid some of the above exposures, there are two important steps you can take to decrease the risk for your baby: Exclusively breastfeed for at least six months to decrease your child's risk for asthma, eczema and food allergies. Do not introduce solid food until after the age of 6 months.

Avoid exposure to cigarette smoke. This applies not only to you now and after the baby is born, but also anyone in the home who smokes — including family and friends.

Alice Y. Chang, M.D., is an instructor in medicine at Harvard Medical School, and on the faculty of the Department of General Medicine at Brigham and Women's Hospital. Her clinical interests and experience are in the fields of primary care, women's health, hospital-based medicine, and patient education.

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Last updated:	January 24, 2007