Caffeine is a stimulant found in coffee, tea, energy drinks, soft drinks, chocolate, frozen desserts, gum and some over-the-counter drugs. According to the Mayo Clinic, consuming more than 500 mg of caffeine a day can lead to insomnia, nervousness, restlessness, irritability, nausea or other gastrointestinal problems, fast/irregular heartbeat, muscle tremors, headaches and anxiety in adults. The chemical can also have lasting effects on babies developing in the womb.
Increased Risk of Miscarriage
A study published in the March 2008 "American Journal of Obstetrics and Gynecology" reported that pregnant women who consume more than 200 mg of caffeine a day (about two cups of coffee) could double their risk of miscarriage. The ACOG responded to this claim by stating, "although some studies suggest drinking three or more cups of coffee per day may increase the risk of miscarriage, there is no proof that caffeine causes miscarriage." However, it does suggest limiting or avoiding caffeine during pregnancy.
Low Birth Weight
The March of Dimes admits that the effect of caffeine on birth weight is likely to be "very small," but reports studies that suggest taking in too much can slightly reduce a baby's birth weight. This can impact the child later in life as low birth weight has been linked to future risk of heart disease and diabetes.
Restricted Blood Flow to the Fetus
According to a 2008 article in "Time," high doses of caffeine can have a vaso-constrictive effect in adults, which could reduce blood flow to the placenta and to the fetus. Improper blood flow between the mother and baby could lead to preterm delivery, birth defects or neurological development. More research is still being conducted to determine specific consequences.
Faster Breathing and Heart Rate, Less Time Sleeping
Caffeine crosses the placenta, so its effects on a developing baby can be similar to those experienced by adults. The Organization of Teratology Information Specialists (OTIS) reports that mothers who consume more than 500 mg of caffeine a day are more likely to have babies with faster heart rates, tremors, increased breathing rate and less time spent sleeping in the days following birth.
Potential Link to Leukemia Risk
No convincing links have been found between caffeine and cancer risks, but a study announced on January 2009 on ScienceDaily.com is rooted in the findings of previous research that did find a correlation between alterations to DNA, sometimes found in newborns, to an increased risk of leukemia. Caffeine has been known to trigger these types of DNA changes. Lifestyle and dietary information will also be considered to determine if other factors could also increase the risk. Past research suggesting a link between caffeine with cancers of the pancreas and kidneys found that the stimulant's effect on cancer risk was unlikely.