Millions of us can't start the day without a cup of joe - or several. Studies show that coffee is Americans' primary source of antioxidants. But the news about java isn't all good. Coffee has several negative health effects, and it's obviously addictive. Here are a few reasons to try quitting. If you're pregnant, the jury's still out on the effects of caffeine on a fetus. Some studies have found a connection between drinking more than two cups a day and the risk of miscarriage. The British Medical Journal found that one cup or more may result in lower birth weight. Coffee is broken down in the liver by enzymes, which become less effective at filtering other toxins in the bloodstream as they process caffeine. Drinking boatloads of caffeine - we're talking more than five cups a day - can cause hallucinations!