Adults who smoke don't just harm their own bodies research shows that they're also putting their children at increased risk of respiratory disease and other health complications. Here's how:
Research shows that mothers who smoke, or spend a lot of time around other smokers during pregnancy, do serious damage to their babies' lungs.
"Babies [of mothers who smoke] are born smaller and have lower lung function at birth," says Dr Peter Sly, respiratory paediatrician and deputy director of the Queensland Children's Medical Research Institute. "That low lung function at birth is one of the major risk factors for chronic respiratory conditions throughout life."
Babies born to parents who smoke are also at greater risk of premature birth, stillbirth, and cleft lip and palette.
Baby girls' eggs can also get damaged, meaning the health impact of smoking can last generations. "Female foetuses exposed to tobacco smoke in utero… their babies will have an increased risk of asthma," professor Sly explains.
While quitting before you conceive is the smartest idea, sometimes it's too late. Dr Sly researched how the health of babies of former smokers compared to that of current smokers and non-smokers. "We found women who gave up smoking before they got pregnant, their baby's immune system was [still] affected," he says. "Even though they had given up before they got pregnant, the effects were still there. We really have to stop, in particular, girls taking up smoking."
The risk of babies developing health problems from smoking parents doesn't stop when they're born. "After birth, if they're exposed to cigarette smoking, they're at much higher risk of bronchiolitis and respiratory infections which lead to them ending up in hospital," Professor Sly says. "There is also an increased risk of middle ear infections and asthma."
And that risk still applies even if the mother quit during pregnancy, then started back up. "If the kids didn't have tobacco smoke exposure before birth but have it in early life, their lungs don't grow as well either and they end up with lower lung function," Professor Sly says.
One in 12 Australian households with children have an indoor-smoker living in their home, which not only puts their child's health at risk, it doubles the chance of them becoming a smoker in later life.
"When the parents say, 'Do as I say, don't do as I do' that doesn't wash," professor Sly warns.
Young people exposed to second-hand smoke at home inhale the equivalent amount of nicotine as someone who smokes 60-150 cigarettes a year. That increases their risk of lung cancer by 20-30 percent.
And the health risks don't stop when children reach adolescence smoking in the car is particularly dangerous. "If teenagers are exposed to cigarette smoke in the car, they're much more likely to have active asthma as teenagers," professor Sly says.
Even if parents have smoked throughout their children's early years, Dr Sly stresses that quitting smoking now will still help their kids' health. "It's a cumulative effect," he says. "We can't undo past mistakes, but we don't have to compound them with present mistakes."