Smoking around pregnant women significantly increases the unborn child’s risk of developing asthma.
Pregnant women are often warned against smoking because of the health detriments it holds for their future child, but less about the dangers of those smoking around them.
The new study links passive smoking – ie, involuntarily inhaling smoke from other people’s cigarettes – with future offsprings’ asthma risk.
Scientists looked at the correlation between fathers who smoked around pregnant mothers and the genetic code of their children.
It was found exposure to smoke can actively alter the genes associated with a child’s immunity, making it more likely they will develop the potentially dangerous respiratory disease.
The study involved 756 children, who were given regular medical exams and DNA testing up to the age of six.
Those whose fathers smoked more than 20 cigarettes daily had a 35% risk of asthma. Babies whose fathers smoked fewer than 20 daily had a 25% risk.
This is comparative to a 22.7% risk for those whose fathers do not smoke.
Published in the journal Frontiers in Genetics, the study is the first of its kind to distinguish between unborn children’s exposure to mothers’ active smoking during pregnancy compared to the passive smoking of those around them.
“We found that prenatal exposure to paternal tobacco smoking is associated with increased methylation of certain immune genes, which alters how the genetic code is read,” said lead study author Dr Chih Chiang Wu.
“This smoking-associated DNA methylation is significantly retained from birth to six years of age and correlates with development of childhood asthma,” added Wu, of Po-Zen Hospital in Taiwan, where the study took place.
What is asthma?
Asthma is a common lung condition which can cause occasional breathing problems, such as wheezing and breathlessness, according to the NHS website.
Sufferers may also experience asthma attacks, which are associated with coughing, wheezing and chest tightness. In serious cases, asthma attacks can prove fatal, according for three deaths in the UK every day.
The risk is greatest for young people in the UK, who are more likely to die from asthma than those in other wealthy countries, new research has suggested.
Asthma often develops in childhood although in rarer cases it begins in adulthood.
There are some 5.4 million people receiving treatment for asthma in the UK, according to Asthma UK.
If you are looking for help quitting smoking, visit the NHS Smokefree website.