Sodas, energy drinks, coffee, even some foods can have too much caffeine for children. It's especially hazardous for children with a heart condition. Pregnant women should also limit their caffeine intake (see chart) to protect the fetus.
“People often don’t understand the potential risk of these beverages,” says Bruce A. Goldberger, director of forensic toxicology at the University of Florida’s pathology labs.
Note that on the chart below 80 mg is the daily limit for a 10-year old, which means a whole bottle of Mountain Dew soda or a cup of ordinary coffee are too much.
Pregnant women are advised not to exceed 200 mg a day, which means two cups of regular coffee are too much as is one 5 Hour Energy shot.
... a teenage girl ... died in 2011 of a heart arrhythmia. The 14-year-old, Anais Fournier, consumed a 24-oz Monster Energy drink at a mall near Hagerstown, Md. The next day, she drank another 24-oz can and then collapsed.
Each can of Monster contains an estimated 240 to 280 mg of caffeine, a daily dose that is considered safe for adults. Fournier, however, was younger and smaller than the average adult and had a preexisting heart condition.
More research on the effect of caffeine on the fetus. Caffeine results in babies that are small for gestational age at birth (SGA) and lengthens pregnancy.
... caffeine freely passes the placental barrier, but the developing embryo does not express the enzymes required to inactivate it efficiently. The WHO currently suggests a limit of 300mg per day during pregnancy but some countries recommend a limit of 200mg, which can be less than a single cup of coffee from some high street cafes.
In this study we found no association between either total caffeine or coffee caffeine and preterm delivery but we did find an association between caffeine and SGA.
For a child of expected average weight (3.6kg) this equates to 21-28g lost per 100mg caffeine per day. But it was not just caffeine, but the source of caffeine, which affected pregnancy outcomes. Caffeine from all sources increased the length of the pregnancy by 5hr per 100mg caffeine per day, but caffeine intake from coffee was associated with an even longer gestational length -- 8hr extra for every 100mg caffeine per day.
This association means that it is not just the caffeine in coffee which increases gestational length but either there must be a substance in coffee which is responsible for the extra time or there is a behaviour associated with coffee drinking not present in women who drink only tea (for example). SGA babies are at higher risk of both short term and lifelong health problems and it seems from these results that since even 200-300mg caffeine per day can increase the risk of SGA by almost a third these recommendations need to be re-evaluated. [emphasis mine]