SUBSTANTIAL VARIATIONS IN the levels of caffeine contained in coffees served in high street cafes have been detected by researchers.

The results of the study by a group in the University of Glasgow have raised concerns about the levels of caffeine being consumed by pregnant women – who are recommended an intake of no more than 200mg each day, reports the BBC.

Britain’s Food Standard Agency says that consuming too much caffeine when pregnant can lead to low birth weight or miscarriage.

A 2008 US study found that pregnant women who drank more than 200mg of caffeine a day faced a 25 per cent greater risk of miscarriage in the first 20 weeks of pregnancy than women who consumed no caffeine, the Telegraph reports.

The group analysed take-away espressos purchased from 20 shops in Glasgow. While a single espresso is assumed to contain about 50mg of caffeine, the study found that levels often considerably exceeded this.

“The analysis that we did showed the amount of caffeine ranged from 50mg per cup from Starbucks, up to over 300mg per cup from another coffee house, Patisserie Francoise” said lead researcher Alan Crozier.

He said that a pregnant woman could exceed her daily allowance by drinking just one of the strongest coffees.

The study is published in the Royal Society of Chemistry’s journal Food and Function