A craving for liquorice during pregnancy could damage the unborn child's intelligence and behaviour.

Scientists at Edinburgh University conducted a study involving eight-year-old kids whose mothers had eaten large amounts of the treat.

They found that the youngsters performed less well in a series of tests of vocabulary, memory and spacial awareness.

They also claim the children were more likely to exhibit disruptive behaviour, to have short attention spans or to suffer from hyperactivity conditions such as ADHD.

Now, the experts believe that liquorice could contain an ingredient which could impair the placenta and allow stress hormones to be passed to the unborn child.

Professor Jonathan Seckl, from the University of Edinburgh's Centre for Cardiovascular Science, said: "This shows that eating liquorice during pregnancy may affect a child's behaviour or IQ and suggests the importance of the placenta in preventing stress hormones that may affect cognitive development getting through to the baby."

The study, carried out by the University of Helsinki and the University of Edinburgh, looked at children born in Finland, where consumption of liquorice among young women is common.

The research followed on from a study which showed that liquorice consumption was also linked to shorter pregnancies.