To me, my only concern is the sugar content in gassy drink. If your baby's weight is towards the high side, it's better to cut down. And if you are at risk of gestational diabetes, try to avoid.
Went to a parenting class and heard that there's this Indonesian mum who has diabetes, her son weighed 8+kg.. not sure how true.
My cousin kept drinking coke light. And then her son came out to be hyperactive and could not sit still. She then blamed it on coke.
Coke has caffeine content in it, which I think reduces the iron absorption. So have to be careful too..