Children whose mothers smoked in pregnancy are more likely to become moody and depressed than other boys and girls, say scientists.
A study of more than 200 children found that those whose mothers were regular cigarette users while they were in the womb had smaller brains and were at greater risk of stress and anxiety.
Researchers suspect tobacco could affect development by destroying neurons and reducing oxygen to the foetus because of the narrowing of blood vessels.
Children whose mothers smoked in pregnancy are more likely to become moody and depressed than other boys and girls, say scientists
The study, published in the journal Neuropsychopharmacology, said smoking throughout pregnancy could have long-term effects on the mental health of young children.
In England and Wales, 17 per cent of women smoke during pregnancy - while, among under 20s, the figure is 45 per cent.
Although most will go on to have a healthy baby, smoking can cause considerable damage to the unborn child.
Exposure to cigarettes in the womb is believed to alter brain structure, but little is known about how the organ's development is affected or if the behavioural problems observed are controlled by these differences.
Dr Hanan El Marroun and colleagues assessed the brains and emotional functioning of 113 six to eight year-olds whose mothers smoked from one to nine cigarettes a day during pregnancy.
Seventeen stopped when they discovered they were pregnant, while 96 continued throughout.
The results were compared to a control group of 113 children unexposed to cigarettes in the womb.
They showed that those whose mothers continued smoking had smaller brains with less grey and white matter.
A study of more than 200 children found that those whose mothers were regular cigarette users while they were in the womb were at greater risk of stress and anxiety
They exhibited more emotional problems - such as depressive symptoms and anxiety and a smaller superior frontal cortex which specifically which controls mood.
Importantly, brain development of children whose mothers quit during pregnancy displayed no such problems.
Dr El Marroun, of the Erasmus Medical Centre in Rotterdam, said: 'It’s well known cigarette smoking can cause serious health problems including cardiovascular diseases and cancer.
'Smoking during pregnancy has also been shown to adversely affect offspring health. Yet up to 25 per cent of pregnant women report smoking during pregnancy.
'Smoking during pregnancy has been linked to spontaneous abortions, reduced growth and sudden infant death syndrome.
'During childhood and adolescence, prenatal tobacco exposure has been associated with behavioural and cognitive problems.
'Furthermore, evidence is accumulating prenatal tobacco exposure is related to psychiatric disorders and mortality from childhood to young adulthood.
Exposure to cigarettes in the womb is also believed to alter brain structure
'Thus having a better understanding of how alterations in the brain due to pre-natal exposure to cigarettes contribute to at-risk states in children is important.
'Largely our results both support and extend the previous neuro-imaging studies in adolescents. For example pre-natal tobacco exposure has been associated with reduction in cortical grey matter in teenagers.'
He said tobacco could affect brain development in the womb through nicotine - which has been demonstrated in animal studies - or disrupt the migration of brain cells.
Another possible explanation is maternal smoking leads to the unborn child being starved of oxygen and nutrients due to the arteries becoming clogged and less blood reaching it affecting growth of the brain.
Dr Marroun said: 'Overall, our findings suggest long-term effects of pre-natal tobacco exposure on brain development and emotional problems in young children.
'The results of the current study in combination with the existing literature about the long-term effects of pre-natal tobacco exposure emphasise the importance of preventing and reducing cigarette smoking during pregnancy.
'Our findings provide further support for the need of clinical and public health strategies aimed at the prevention of pre-natal tobacco exposure of children.'
He said more research is needed to explore the structural and functional neuro-developmental effects of prenatal exposure to tobacco.
Researchers now estimate that each year in England and Wales several hundred babies are born with a physical defect directly caused by their mother’s smoking.
Every year in England and Wales, around 3,700 babies in total are born with such a condition.
The chance of a baby being born with missing or deformed limbs because of its mother’s smoking is 26 per cent higher - and cleft lip or palate is 28 per cent more likely.
Similarly, the risk of club foot is 28 per cent greater and gastrointestinal defects 27 per cent more.
Skull defects are 33 per cent more likely and eye defects 25 per cent more common.
Of the 700,000 babies born each year in England and Wales, around 120,000 babies are born to mums who smoke.
Read more: http://www.dailymail.co.uk/health/article-2449240/Babies-born-mums-smoke-pregnant-smaller-brains-anxious-moody-children.html#ixzz2h9Mo0mi0
Follow us: @MailOnline on Twitter | DailyMail on Facebook
