The peripheral circumstances of all the cases would have to be thorughly examined. People take this stuff when they are in some kind of distress by definition. If someone is hung-over, or coming down from some drug, or simply over-worked, these conditions could lead to all the symptoms described.
As far as using the word abortion, that certainly does imply intent. A women can no more have a spontaneous abortion than she could have a spontaneous appendectomy. Abortion is a medical or intentional procedure and does not happen spontaneously. Miscarriage happens spontaneously.
This whole thing is suspect and my trained sniffer nose smells a law firm out there looking to get paid off.
Note that the Daily Mail originates in London, so there are probably some British/American differences in the language that come into play here in regard to "spontaneous abortion" vs. "miscarriage."
As for the claims themselves... from personal experience I can say that sudden death is certainly plausible. There was this friend of mine, 19 years old, and apparently one morning he downed several Monster Energy drinks in a row on an empty stomach. This was on top of the fact that he had a (generally benign) heart condition, and when he went out to exert himself (he was playing some sports with friends) he dropped dead of a heart attack.
However, I am almost certain that in his case, as well as the ones being discussed here, that abuse of the product was at fault, not the product itself. Virtually all of the energy drinks out there warn users not to drink them en masse. (Monster is notoriously vague in that regard; they sell a 32-ounce can of their stuff. I tried a smaller can once, and even though I've handled other energy drinks without any problems before, that stuff made me very uncomfortable. Never again.)