Risk Factors:

Asthma affects about 7 million American children ages of 5 - 14. Asthma has dramatically increased worldwide over the last few decades, in both developed and developing countries. Asthma is the most common chronic childhood illness. About half of all cases of asthma develop before the age of 10, and about 80% of patients develop symptoms before they are 5 years old.

Gender

Among younger children, asthma develops twice as frequently in boys as in girls, but after puberty it is more common in girls.

Race and Ethnicity

African-American children have significantly higher rates of asthma than Caucasian children. Hispanic children are also at higher risk. Both groups of minority children are more likely to have fatal asthma than Caucasian children. Ethnicity and genetics, however, are less likely to play a role in these differences than socioeconomic differences, such as having less access to optimal health care, and greater likelihood of living in an urban area. Caucasian children who live in cities also face a high risk for asthma.

Issues Surrounding Birth

A variety of pregnancy and perinatal factors have been associated with risk for asthma, although none are very well studied or proven. Results from studies include:

• Low Birth Weight. Infants of low birth weight are at higher risk for lung problems and asthma.
• Winter Birth. Children born in the winter may have a greater risk for asthmatic allergies to cockroaches than children born at other times of the year.
• Breastfeeding. Exclusively breastfeeding for a babyâ ' s first 3 months of life may help reduce the risk for wheezing and asthma during their early. However, it is unclear whether the protection will last into later childhood. Breastfeeding has many other benefits for the child. The American Academy of Pediatrics recommends exclusively breastfeeding for the child's first 6 months.
• Complications of Pregnancy. Complications of pregnancy, specifically those involving the mother's uterus (such as post-birth hemorrhage, pre-term contractions, insufficient placenta, and restricted growth of the uterus), are associated with an increased risk of childhood asthma.

Obesity

Studies report a strong association between obesity and asthma. Evidence also suggests that people who are overweight (body mass index greater than 25) have more difficulty getting their asthma under control. Weight loss in anyone who is obese and has asthma or shortness of breath helps reduce airway obstruction and improve lung function. [For more information, see In-Depth Report #53: Weight control and diet.].

Other Risk Factors

GERD. At least half of patients with asthma also have gastroesophageal reflux disease (GERD), the cause of heartburn. It is not entirely clear which condition causes the other or whether they are both due to common factors. Treating GERD does not appear to improve asthma control. [For more information, see In-Depth Report #85: Heartburn and gastroesophageal reflux disease.]

Aspirin-Induced Asthma. About About 10% of adults and fewer children have aspirin-induced asthma (AIA). With this condition, asthma gets worse when patients take aspirin or other nonsteroidal anti-inflammatory drugs (NSAIDs). AIA often develops after a viral infection. It is a particularly severe asthmatic condition, associated with many asthma-related hospitalizations. In about 5% of cases, aspirin is responsible for a syndrome that involves multiple attacks of asthma, sinusitis, and nasal congestion. Such patients also often have polyps (small benign growths) in the nasal passages.

Patients with aspirin-induced asthma (AIA) should avoid aspirin andother NSAIDs, including ibuprofen (Advil) and naproxen (Aleve).