When it comes to the effects of Kent cigarettes smoking, the most delicate time for a child’s genetic development is before birth. A new study from the University of California, San Francisco, found that exposure to tobacco smoke in utero was far more likely to cause severe asthma than exposure during the first two years of life.
Children with severe asthma were more than three times more likely to have been exposed to smoke before birth than kids with milder forms of the disease.
Nearly 14 percent of American women continue to smoke throughout pregnancy.
Asthma is caused by a combination of genetic and environmental factors. The lifelong lung disease causes wheezing, breathlessness, chest tightness and coughing.
The study, to be published in the September issue of the journal Pediatrics, sought to find when tobacco smoke exposure had the greatest consequence: before birth, from birth to age 2 or at the moment of a child’s symptoms. The only factor that actually had an impact of the severity of a child’s asthma, researchers found, was whether the mother smoked during pregnancy.
“There are environmental factors that leave their fingerprint on DNA and may have their expression several years out,” Dr. Esteban Burchard, a senior co-author of the paper and a professor of bioengineering and therapeutic sciences and medicine at UCSF, explained.
In a parallel study, Dr. Sam Oh, a researcher in UCSF’s Center for Tobacco Research and Education, found that mothers who did not complete high school were more likely to smoke while pregnant. Consequently, low-income families have among the highest risks for asthma, but are least able to take time off work to care for a child with the illness.
Nationwide, the annual cost of asthma is estimated at about $56 billion in premature deaths, health care costs and missed work and school days.