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. 
 
 The fact that tobacco use affects genetic activity is widely known. 
 
 And the fact that parents’ behavior before conception can influence gene expression is emerging: A man’s weight at the time of conception can increase the likelihood of the child becoming overweight, suggests recent research, and what women eat just before conceiving can change a child’s DNA for life. 
 
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 Now it appears that, on a genetic level, these behavioral influences can extend back another generation. 
 
 Children whose grandmothers smoked while pregnant with their mothers – even when their mothers did smoke while pregnant — were 10 to 22 percent more likely to have asthma. The data was gathered from nearly 45,000 grandmothers and over 65,000 grandchildren in Sweden. 
 
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 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. 
 
 The next step is to study the sins of the (grand)fathers, say the researchers: Would the same thing happen if a grandfather smoked at the time of conception? ||||| 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. Nobody knows for certain why this is the case. Some people think it's to do with changes in the environment (nurture), others think the clues may lie in our genes (nature). 
 
 A recent hot topic of research is 'epigenetics'. It is the study of how the environment influences how genes express themselves (nature and nurture). 
 
 It was discovered fairly recently that epigenetic changes can be passed down from one generation to the next. In other words, the environment that your grandparents grew up in can still influence your genes today. 
 
 Some animal studies have found that nicotine exposure is associated with epigenetic changes that can be passed down through the generations. 
 
 In this study, researchers at the University of Melbourne in Australia and Umea University in Sweden wanted to know if the same is true in humans. Does smoking during pregnancy cause some change that is passed down through the generations? In particular, if a grandmother smokes during pregnancy, does it have an influence on her granddaughter's risk of developing asthma? 
 
 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. 
 
 The grandmothers' smoking habits were recorded as non-smokers, smoking from 1-9 cigarettes a day and smoking 10 or more cigarettes a day. 
 
 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. In other words, the risk seemed to jump an entire generation. 
 
 In a statement, Dr Caroline Lodge, a researcher at the University of Melbourne and one of the authors of the study, says: "We found that 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. 
 
 "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. 
 
 For the next stage of their research, the team will look at whether the risk of developing asthma can be passed through the male line of the family. In other words, they will estimate the risk of asthma in grandchildren whose grandmothers smoked while pregnant with their fathers. ||||| Children with grandmothers who smoked have an increased risk of asthma even when mothers did not smoke, according to new findings. 
 
 The new study, presented today (30 September, 2015) at the European Respiratory Society's International Congress, 2015, is the first to investigate the risk in a whole population and use evidence about smoking habits taken directly from grandmothers at the time they were pregnant. 
 
 There has been a rapid increase in asthma in the last 50 years. Changing environmental exposures are thought to be responsible for this and more recently researchers are looking at these exposures in previous generations. 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. 
 
 Researchers investigated whether smoking in grandmothers, while they were pregnant with daughters, was linked with an increased risk of asthma in their grandchildren. Data was taken from the Swedish Registry and included 44,853 grandmothers from 1982 to 1986. Smoking exposure was recorded during pregnancy and use of asthma medication was recorded in 66,271 grandchildren. 
 
 The results found that if grandmothers had smoked whilst they were pregnant, there was an increased risk of asthma in grandchildren, even if their mothers had not smoked during pregnancy. The risk of asthma was increased by 10 to 22%. 
 
 Dr Caroline Lodge, an author of the study and Research Fellow at the University of Melbourne, Australia, said: "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." 
 
 "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. Additionally, researchers in this area need to be aware, when interpreting the asthma risk from current exposures and genetic predisposition, that individuals may carry an inherited, non-genetic, risk from exposures in previous generation. This knowledge will help to clarify the findings concerning current risk factors in asthma research." 
 
 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. The findings also encourage research into inherited disease risks for other environmental exposures." 
 
 ### 
 
 Notes to editors: 
 
 Abstract: LATE-BREAKING ABSTRACT: Does grandmaternal smoking increase the risk of asthma in grandchildren? 
 
 Session: Early life matters: prematurity and risk factors for asthma 
 
 Date and time: Wednesday 30 September, 08.30-10.30 
 
 Room: 13.1 
 
 The study was funded by the Department of Public Health and Clinical Medicine, Umeå University 90187 Sweden and Asthma Australia, through a Lillian Roxon travel grant. 
 
 Caroline Lodge conducted this work as a postdoctoral fellow in Umeå University and is also supported by a National Health and Medical Research Council Early Career Fellowship at University of Melbourne.
– 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.)