A study from the University of Glasgow found that one high street cafe was selling coffee with a caffeine count six time higher than the lowest.
The researchers said the levels have potential health concerns for expectant mums and women on the Pill.
The study found that in some cases, drinking just a single serving of espresso coffee from some outlets could increase the risk of dangerous caffeine toxicity. This can cause headaches, chest pain, anxiety, increased heart rate and abdominal cramps.
High caffeine consumption during pregnancy can lead to low birth weight babies, which then increases the risk of high blood pressure, Type 2 diabetes and heart disease later life.
The UK Food Standards Agency recommends a limit of 200mg of caffeine a day for pregnant women, the equivalent of four cups of strong coffee.
Does this surprise you?
Did you avoid coffee in pregnancy?