Experts recommend that pregnant women limit the amount of caffeine they drink each day. Women consuming high levels of caffeine during their pregnancy can result in their baby having a low birth weight or even miscarriage. It is recommended that you do not have more than 200mg of caffeine a day.

The amount of caffeine found in some foods and drinks is as follows:

one mug of instant coffee: 100mg
one mug of filter coffee: 140mg
one mug of tea: 75mg
one can of cola: 40mg
one can of energy drink: up to 80mg
one 50g bar of plain chocolate: most products on the UK market contain less than 25mg
one 50g bar of milk chocolate: most products on the UK market contain less than 10mg

So, in one day, you will almost reach your 200mg limit of caffeine if you have:

two mugs of tea and one can of cola
one mug of instant coffee and one can of energy drink