New research published by the University of Glasgow suggests that the variations in the amount of caffeine in each coffee served in high street stores could pose risks to pregnant women. Read the detailed article here: http://www.bbc.co.uk/news/uk-scotland-glasgow-west-15968515
In small amounts caffeine is not harmful but too much can have detrimental effects on your baby. The Department of Health recommend drinking no more than two mugs of regular coffee per day which makes this new research particularly worrying. Many other foods and medications also contain caffeine and so it is easy to see how someone may exceed their recommended 200mg/day limits (especially in light of this new research).
The best advice is to always ask about the caffeine content of a specific beverage before you buy from coffee shops. If the amount is unknown it is probably best to avoid. As this study points out, there is huge variation between brands and different types of coffee and it is always better to be safe rather than sorry.