Mothers who smoke during pregnancy 'put children at risk of obesity later on'
Smoking may lead to subtle structural variations in the growing brain of the unborn baby Figures show one in seven women smoked in pregnancy in England last year
19:11 GMT, 3 September 2012
Smoking during pregnancy: Could cause problems in brain development of baby
Women who smoke in pregnancy could be putting their children at greater risk of being fat as teenagers, warn researchers.
They fear that smoking leads to subtle structural variations in the growing brain of the unborn baby that create a preference for eating fatty foods.
Smoking during pregnancy is already linked to low birthweight and premature delivery of the baby, but evidence is now emerging of the way in which it affects the child's health in the long-term.
Dr Amirreza Haghighi, of the Hospital
for Sick Children, Toronto, Canada, who led a new study, said 'Prenatal
exposure to maternal cigarette smoking is a well-established risk
factor for obesity, but the underlying mechanisms are not known.
'Preference for fatty foods, regulated in part by the brain reward system, may contribute to the development of obesity.'
The research comes as experts predict two out of three children could be obese by 2050 if current trends continue. More than one in five is obese at present – so fat it threatens their health.
The study recruited 378 adolescents age 13 to 19 years of which almost half had mothers who smoked during pregnancy.
They were carefully matched with the remaining participants whose mothers didn't.
Maternal smoking was defined as having a mother who smoked more than one cigarette a day during the second trimester of pregnancy, while the mothers of the remainder did not smoke one year before or during the pregnancy.
Babies born to women who smoked weighed less at birth and were breastfed for shorter periods of time.
researchers found the teenagers whose mothers smoked had a marginally
higher body weight and Body Mass Index (BMI), a measure of weight
related to height. They also had significantly higher total body fat
compared with adolescents whose mothers did not smoke in pregnancy.
The other significant difference was noted by researchers on brain scans.
found teens whose mothers smoked while they were in the womb had a
lower volume of the region called the amygdala, which plays a role in
processing emotions and storing memories.
part of the brain also appears to have a role in limiting fat intake,
and the researchers found that as amygdala volume fell, fat intake went
Teenagers may find it harder to resist sweet and fatty foods if their mothers smoked when pregnant with them (file picture)
'Prenatal exposure to maternal cigarette smoking may promote obesity by enhancing dietary preference for fat, and this effect may be mediated in part through subtle structural variations in the amygdala' say the researchers in a report published Online First in the Archives of General Psychiatry journal.
Latest figures show 13.4 per cent of women smoked in pregnancy in England last year, down from 15 per cent on 2006-07.
Cutting smoking during pregnancy is one of three national aims in the government's tobacco control plan, published in March last year.
The aim is to have cut the number of women smoking at the time of giving birth to no more than 11 per cent by the end of 2015.
Dr David Haslam, chairman of the UK's National Obesity Forum, said it was clear that a mother's dietary and other choices in pregnancy could 'switch on' bad genes.
He said 'We're seeing the results of the new science of epigenetics in which genes can express proteins, or become activated, by what happens in pregnancy.
'Everyone knows that smoking is bad for you, and we've seen clear evidence of the health risks over the last 50 years.
'But now there are even more reasons for a pregnant woman to avoid smoking, and press home the message that obesity begins in the womb.
'You can give your child the best start in life and help them avoid obesity at the same time' he added.