I'd not. It's not just the caffeine but all the other crap stuff that is in it that isn't good for LO either.
I'd be inclined to cut it out altogether. I'd not drink any energy drinks tbh. If I need an energy boost I'd eat a banana or something.
I found all of the following if you are interested
FSPB Stimulant Drinks Report Released
Commenting further Professor Sean Strain, Chairman of the Stimulant Drinks Committee said "The Committee was constrained by the limited amount of comprehensive information, risk assessment data and peer reviewed scientific research in this area. In light of this limited information and in order to protect public health, we have adopted a precautionary approach to its review."
The report makes the following recommendations:
a) stimulant drinks should be labelled with an indication that they are unsuitable for children (under 16 years of age), pregnant women and individuals sensitive to caffeine.
b) they should be classified with other beverages of high caffeine content.
c) the consumption of stimulant drinks by children under 16 years should be discouraged.
d) caution should be exercised in the consumption of stimulant drinks with alcohol.
e) they should not be consumed in association with sport and exercise as a thirst quencher.
f) they are unsuitable rehydration agents for use in sport and during exercise.
Groups for special consideration
In the context of advice to pregnant women to limit caffeine intake owing to the possible adverse effects of high caffeine intake on pregnancy outcome, stimulant drinks should be classified with other beverages of high caffeine content.
Taken from here
Also other reading tells me that it contains other stimulant ingredients that are no nos. Apparently as LO's heartbeat is so fast already, something like Red Bull which acts as a stimulant can elevate it further.
There is also the debate that too much caffeine can increase the risk of miscarriage. Does Red Bull carry a warning for PG women to not drink it? In a few reports I've read it mentions the MC risk increase from overdoing caffeine.