Grandmothers who smoked while they were pregnant are more likely to have grandchildren with asthma — even when mothers did not smoke during pregnancy, according to new research.  Grandma's smoking affects grandchildren's asthma 
 
 
 
 WebMD UK Health News By Clint Witchalls WebMD UK Health News 
 
 30th September 2015 - If your grandmother smoked, you may be at increased risk of asthma even if your mother didn't smoke, according to new research presented at the European Respiratory Society's International Congress. Asthma cases rising 
 
 The incidence of asthma has risen over the past 50 years. It is known that tobacco use can affect the activity of genes and the researchers in this new study hypothesised that these changes could then be passed to subsequent generations. To do this, the researchers examined data on nearly 45,000 grandmothers taken from the Swedish Registry. Whether or not the grandmothers smoked during pregnancy was recorded in the registry, as was any subsequent use of asthma medication by their grandchildren. Inherited risk 
 
 The analysis revealed that grandchildren, between the ages of 1 year and 6 years, had a 10 to 22% increased risk of developing asthma if their grandmothers smoked during early pregnancy, even if their own mothers had not smoked during pregnancy. Blog: Couples Share Similar Genetics 
 
 Rates of asthma have been soaring in recent decades, and this new information can also help asthma researchers better understand “risk from exposures in previous generations,” study author Caroline Lodge said in a release. This may also be important in the transmission of other exposures and diseases." "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," she adds. Professor Bertil Forsberg, presenting author of the study from Umeå University, Sweden, said: "The next stage for the research team is to investigate the potential inheritance of asthma risk through the male line, by assessing the risk of asthma in grandchildren whose grandmothers smoked whilst pregnant with their fathers.
– Nobody should need another reason not to smoke while pregnant, but researchers have found one: A study that looked at tens of thousands of grandmothers and grandchildren in Sweden found that children whose maternal grandmothers smoked were up to 22% more likely to have asthma, even if their mothers never took up the habit, Discovery reports. Researchers knew that nicotine exposure caused genetic changes in animals that could be passed down through generations, and the study set out to determine whether the same "epigenetic inheritance" happened with humans who smoke, reports WebMD. "We found that smoking in previous generations can influence the risk of asthma in subsequent generations. This may also be important in the transmission of other exposures and diseases," study co-author Caroline Lodge says in a press release. The researchers say the inheritance of risk could help explain why there has been a steep rise in asthma cases over the last 50 years, even though smoking rates have declined. They now plan to investigate whether the same risk is passed down through the male line by looking at people whose grandmothers smoked when they were pregnant with their fathers. (Canadian researchers found that the stress of women who were pregnant during an ice storm showed up in their children's DNA.)