New research from Finland has confirmed that women should avoid consuming large amounts of liquorice during pregnancy, however the limit for safe consumption is still unknown.
The study, which was carried out by the University of Helsinki, the National Institute for Health and Welfare and the Helsinki and Uusimaa hospital, looked at 378 children around 13 years of age whose mothers had consumed either "large amounts" or "little/no" liquorice during pregnancy.
The study defined a large amount as over 500 mg of glycyrrhizin per week the main constituent of liquorice -- and little or no liquorice as less than 249 mg glycyrrhizin per week.
A total of 500mg of glycyrrhizin corresponds on average to 250g of liquorice.
Glycyrrhizin is already known to cause higher blood pressure and shorter pregnancies, however previous studies have not proven any long-lasting effects on the fetus until now.
To look at these long-tern effects participants were asked to complete cognitive reasoning tests carried out by a psychologist.
The team found that those children who were exposed to large amounts of liquorice in the womb had lower test results than those who were exposed to smaller amounts or no liquorice a difference equivalent to approximately seven IQ points.
In addition children exposed to high levels of liquorice also showed lower tests results in tasks measuring memory capacity.
Parents also reported that these children showed more ADHD-type problems than others, and in girls puberty also started earlier and advanced further.
In Finland the National Institute for Health and Welfare already places liquorice in the 'not recommended' category for pregnant women, but states that occasional consumption of small amounts of liquorice, such as a portion of liquorice ice cream or a few liquorice sweets, poses no danger.
The researchers now advise that both pregnant women and those planning on becoming pregnant should be made more aware of the harmful effects that glycyrrhizin-containing products -- such as liquorice and salty liquorice -- may have on their unborn child.
The results can be found online published in the American Journal of Epidemiology.