Kids born to smoking mums more anti-social
Kids born to mums who smoke are more likely to be an antisocial teen and their loutish behaviour increases the more their mums puff away.
They are more at risk of getting a criminal record for violence, theft or vandalism than those who were not exposed to tobacco toxins in the womb.
Although the numbers of mums who smoke has dropped those who do tend to be teenage mums and the poorest in society.
The study compared mums who admit to smoking during pregnancy and the criminal records of their children.
It found mothers of nearly three fifths of anti-social teens - 59 per cent - had smoked while pregnant with them, and in just over a third of cases, their mothers had smoked at least one pack of cigarettes a day.
Smoking an extra pack of cigarettes a day was associated with 30 per cent greater odds of her child exhibiting three or more symptoms of conduct disorder as a teen and a more than tripling in the odds of three or more symptoms of antisocial personality disorder as an adult.
And it was linked to a more than doubling in the odds of her child having a record of non-violent offences as a juvenile and of committing a violent offence as an adult.
Previous studies had suggested a link between maternal smoking during pregnancy and the antisocial behaviour of their offspring but it is still not clear whether this association is causal or influenced by genetic and environmental factors.
So scientist from Brown University and the University of Maryland used a particular statistical approach known as between-within decomposition, that can tease out any differences between families and within the same family.
The study involved 3,443 children now aged aged 18 to 33 of women who took part in the Boston and Providence centres of the Collaborative Perinatal Project (CPP) between 1959 and 1966.
The CPP looked at factors before and around birth that might influence the mental, neurological, and physical capabilities of that child.
Of these 1,684 adults from 1,248 families in Boston and Providence were formally interviewed when they were 39, on average, about their behaviour as a teen and as an adult.
The study published in the BMJ's Journal of Epidemiology & Community Health said the findings were independent of other factors often linked to smoking in pregnancy.
This suggested smoking while pregnant may have a small to moderate causal effect on the risk of antisocial behaviour in the offspring.
Dr Angela Paradis at the Department of Epidemiology at Brown University School of Public Health said: "Maternal smoking during pregnancy was found to be associated with a range of antisocial behaviours measured by self-report and official records.
"Associations were not specific to antisocial behaviour characterised by violence or aggression.
"Our findings, particularly those based on within-mother estimates, suggest that the elevated risk of antisocial behaviour is independent of other family attributes more common among women who smoke during pregnancy, such as a history of mental illness and lower y socioeconomic status, and may be directly attributable to smoking exposure.
"The current work also highlights, based on our more precise total estimated effects, that any potential causal effect of maternal smoking during pregnancy on offspring antisocial behaviour is most likely small to moderate in magnitude
"In summary, findings from this study support a causal association between maternal smoking during pregnancy and offspring antisocial behaviour.
"Many important risk factors for antisocial behaviour are not modifiable for example sex or family history, but maternal smoking during pregnancy is potentially modifiable and remains prevalent among particular subgroups of women, including teenage mothers and mothers with less than a high school education..
"So although maternal smoking during pregnancy may result in only slight-to-moderate increases in an offspring's risk of antisocial behaviour , removing this exposure may have substantial impacts at the population level."