Moms-to-be, please note -- just avoid cell phones, for a study has revealed that using mobiles during pregnancy could significantly raise your unborn child's risk of developing behavioural problems later in life.

What's more shocking is that the 15-year-long study by international researchers has found that exposure to mobile handsets can also affect the heart rate of an unborn child to some extent.

Researchers have based their findings on an analysis of health data of 13,000 mothers in Denmark who were recruited in early pregnancy and followed until their kids were seven, The Daily Telegraph reported.

The study concluded that the use of mobile phones by pregnant women -- even as little as two or three times a day -- was enough to up the risk of hyperactivity and behavioural problems in kids.

It found that those who used phones while pregnant were 54 per cent more likely to report behavioural problems in their children, including hyperactivity and emotional and relationship difficulties.
 
Problems were even more likely among children whose mothers had used phones while pregnant and who had used cells themselves before the age of seven -- they were 80 per cent more likely to suffer from behavioural difficulties compared to youngsters who had not been exposed to mobile phone use.

In addition, those kids were 25 per cent more at risk of emotional problems, 24 per cent more likely to have difficulties relating to other children, 35 per cent more likely to be hyperactive and 49 per cent more likely to have problems with behaviour.

The study has been published in the latest issue of the Epidemiology journal.