Regardless of whether a mother smokes, a grandmother who once did may affect her grandchildren's health.
A new study from Australia and Sweden found that children of grandmothers who smoked while pregnant may have an increased risk of asthma — even if their mothers didn't smoke.
"For us to understand more about the asthma epidemic, we require a greater understanding of how harmful exposures over your lifetime may influence the disease risks of generations to come," said study co-author Caroline Lodge, PhD, a professor in population and global health at the University of Melbourne in Australia, in a press release.
Asthma is a chronic lung disease that causes the airways to narrow and become inflamed. Symptoms include wheezing, shortness of breath and chest tightness. When these symptoms become severe and difficult to control, it's known as an asthma attack.
According to the Centers for Disease Control and Prevention (CDC), about 25 million adults and children have asthma in the US. In 2013, 3,630 people died from asthma attacks.
In recent years, asthma rates have been increasing. According to the CDC, the number of asthma patients in the US grew by 4.3 million from 2001 to 2009.
For this study, Dr. Lodge and team looked at data from the Swedish Registry on 44,853 women who gave birth between 1982 and 1985. Of their female children, 46,197 also became mothers.
These researchers then looked at the asthma medication intake of the 66,271 grandchildren who were born between 1996 and 2000.
Grandchildren (ages 1 to 6) of grandmothers who smoked during pregnancy were found to have a 10 to 22 percent increased risk of asthma.
According to Dr. Lodge and team, these findings contribute to past studies on the environmental risks of asthma, such as exposure to pollutants and secondhand smoke.
This study was presented Sept. 30 at the European Respiratory Society's International Congress in the Netherlands. Research presented at conferences may not have been peer-reviewed.
Umeå University, Asthma Australia, and the National Health and Medical Research Council funded this research.
No conflicts of interest were disclosed.