New research has found babies are more likely to develop asthma if their father smoked as a teenager.
Medical experts said the information should be used to educate young men about the dangers smoking could have on their unborn children.
The Thoracic Society of Australia and New Zealand said a child was 70 per cent more likely to develop the disease after researchers followed parental smoking habits and their child’s health.
Researchers studied the smoking habits of more than 13,000 men and women.
University of Melbourne researcher Dr Jennifer Koplin said the study started in the 1990s.
“What we found was that fathers who smoked, particularly those who started smoking before the age of 15, had children who were 70 per cent more likely to have asthma,” she said.
Interestingly, the study found there was no link between a mother who smoked before pregnancy and childhood asthma.
Now researchers were trying to determine how the impacts of smoking were passed on.
“They’ve been followed up three times since then,” Dr Koplin said.
“The surveys were roughly 10 years apart, so over that time they’ve started a family and many of them have had kids themselves.
“We’ve been able to trace things that have happened to them over time and then what’s happened to their children as they grow up.”
Dr Koplin said the results would be used to discover other harmful exposures.
“We know that there are effects smoking has on the sperm, called epigenetic changes, so these are changes – they don’t change the DNA but they change the way genes from the DNA are expressed,” she said.
“[Researchers will] now try and work out what some of the mechanisms are that are causing this increase in asthma.
“Once we know that, we’ll know about other exposures that might be important, because we think it might not be just smoking, it might be other things that fathers are exposed to.”
The findings were presented at the annual scientific meeting of the Thoracic Society of Australia on Queensland’s Gold Coast.
Dr Jennifer Koplin said researchers also looked at other environmental factors that impacted on offspring.
“We thought that welding was something that could have similar effects to smoking, in terms of impacts on sperm development,” she said.
The research found that was true.