New York: Moms-to-be please note! Exposure to secondhand smoke during pregnancy may increase children`s risk of developing behaviour problems, a new study has warned.
The study showed that children whose mothers were exposed to secondhand smoke for at least 30 minutes daily were more than twice as likely to have attention and aggression problems at age 5 as the children whose mothers reported no secondhand smoke exposure.
This is one of the first studies to link a mother`s exposure to secondhand smoke during pregnancy to child behaviour problems.
Researchers led by Jianghong Liu, associate professor of nursing at the University of Pennsylvania School of Nursing evaluated more than 600 mother-child pairs in Jintan, China.
The researchers asked mothers to recall how frequently they had been exposed to secondhand smoke during pregnancy, and also measured behaviour problems in the children at ages 5 or 6 using a common behaviour scale.
Thirty-seven per cent of the mothers in the study reported exposure to secondhand smoke during pregnancy. The results showed that 25 per cent of the children whose mothers were exposed to secondhand smoke showed attention and aggression problems, whereas only 16 per cent of the children whose mothers were not exposed showed behaviour problems.
Smoking by women is highly stigmatised in China, so the researchers did not ask the study women whether they had smoked during pregnancy, though the researchers acknowledged that it is possible that several mothers may have smoked.
More than three-quarters of the fathers in the study who stopped smoking at home while their wives were pregnant resumed smoking once the baby was born.
The study didn`t account for the effects of exposure to secondhand smoke after the baby was born, but other research has shown that smoking near a baby has harmful effects on the child`s health, Liu said.
Although the researchers accounted for other variables that could affect children`s behaviour problems - such as parents` histories of psychological problems, maternal age at childbirth, a child`s gender and the levels of lead in the blood - they can`t say for certain whether any other factors influenced the results of the study.
Additionally, the researchers noted that a recent Canadian study found that tobacco products from China contained about three times the amount of heavy metals linked to behaviour problems - such as lead, cadmium and arsenic - than the levels seen in Canadian tobacco products.
The study was published in the journal NeuroToxicology.