IRISH children whose mothers smoked during pregnancy have a higher risk of behavioural problems by the time they reach the age of nine.
New research shows that children whose mothers smoked during pregnancy were up to 78pc times more likely to be classed as having a behavioural problem by their teacher than children of mothers who did not smoke.
Dr Cathal McCrory of Trinity College conducted the research with Professor Richard Layte of the ESRI. Dr McCrory said: "It has been known for some time that smoking during pregnancy is associated with premature birth and low birth-weight, but the results of this study show that the effects of smoking during pregnancy are long-lasting.
"They can affect aspects of the child's emotional and behavioural development in later life. These findings reinforce the need for programmes aimed at promoting successful cessation of smoking during what is a critical period for the developing infant."
The report found that children whose mothers were occasional smokers were 32pc more likely than non-smokers to display behavioural problems. But children whose mothers were heavy smokers, lighting up more than 11 times a day during pregnancy, were 78pc more likely to be defined as having behavioural problems.
"Since smoking in pregnancy is strongly associated with low income and deprivation, which are themselves linked with higher levels of behavioural problems in children, this study used methods to isolate the direct effect of smoking," the researchers added.
The findings are based on the Growing Up in Ireland study published in the 'Journal of Abnormal Child Psychology'.
The proportion of mothers who smoke during pregnancy has fallen over time from 28pc in the late 1990s to 17.6pc currently. The level of smoking in pregnancy in Ireland is higher than in northern Europe but lower than in the UK.
Professor Luke Clancy, consultant physician and board member of ASH, said services to help pregnant women stop smoking are inadequate. He added that many are unaware of the full extent of the health problems to which they are exposing their unborn child.
"Smoking in pregnancy is associated with low birth weight, many women know this. . . but it's also associated with increase admissions to ICU and slow development, both physical and mentally."
He said smoking during pregnancy is more prevalent in lower socio-economic groups and children are left with long-term health problems.
"This burden is falling on people who already have a lot of problems. . . It compounds trouble on top of trouble," he said.
In its pre-Budget submission, ASH called for a 60c increase on the price of 20 cigarettes.