Pregnant mums who regularly use mobile phones may be more likely to have kids with behavioural problems, particularly if those children start using mobile phones early themselves, suggests research published online in the Journal of Epidemiology and Community Health.
The researchers base their findings on more than 28,000 seven year olds and their mothers who were part of the Danish National Birth Cohort (DNBC) study.
This study enrolled nearly 100,000 pregnant women between 1996 and 2002, with the intention of tracking their kids' long term health.
The mums supplied detailed information on their lifestyle, dietary and environmental factors during the course of four lengthy phone interviews during and after pregnancy.
When their children reached the age of 7, the mums were quizzed again about their and their kids' health, including behaviour, which were scored using validated assessments. They were also asked to provide details of their mobile phone use during pregnancy and their kids' mobile phone use.
The researchers had already studied a group of mothers and their 13,000 children from the DNBC and found similarities between the two groups.
In the new group, more than a third (35%) of the 7 year olds were using a mobile phone compared with 30% of the previous group. And whereas around one in 10 children of the previous group were jointly exposed to mobile phones before and after birth, this applied to 17% of the new group.
In both groups, around 3% of children were considered to have borderline behavioural problems, and similar proportions were categorised as exhibiting abnormal behaviour.
Children in both groups exposed to mobile phones before and after birth were 50% more likely to have behavioural problems, after taking account of a wide range of influential factors.
Those exposed to mobile phones before birth only were 40% more likely to have behavioural problems, while those with no prenatal exposure but with access to them by the age of 7 were 20% more likely to exhibit abnormal behaviours.
The authors say that these new results back their previous research and reduce the likelihood that this could have been a chance finding.
And they conclude: "Although it is premature to interpret these results as causal, we are concerned that early exposure to cell phones could carry a risk, which, if real, would be of public health concern given the widespread use of this technology."