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Approximately 15–25% of recognized pregnancies end in miscarriage. However, many miscarriages often occur before a woman even knows she is pregnant.
More than 2,500 barbiturates have been synthesized. At the height of their popularity, about 50 were marketed for human use.
Cancer has been around as long as humankind, but only in the second half of the twentieth century did the number of cancer cases explode.
The Centers for Disease Control and Prevention (CDC) was originally known as the Communicable Disease Center, which was formed to fight malaria. It was originally headquartered in Atlanta, Georgia, since the Southern states faced the worst threat from malaria.
The familiar sounds of your heart are made by the heart's valves as they open and close.