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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.
Before a vaccine is licensed in the USA, the Food and Drug Administration (FDA) reviews it for safety and effectiveness. The CDC then reviews all studies again, as well as the American Academy of Pediatrics and the American Academy of Family Physicians. Every lot of vaccine is tested before administration to the public, and the FDA regularly inspects vaccine manufacturers' facilities.
Your heart beats over 36 million times a year.
More than 2,500 barbiturates have been synthesized. At the height of their popularity, about 50 were marketed for human use.
The ratio of hydrogen atoms to oxygen in water (H2O) is 2:1.
![Frederick Douglass, having escaped from slavery in 1836, attracted large audiences as an antislavery](https://biology-forums.com/gallery/47/medium_375348_18_08_15_9_36_29_223002244.jpeg)
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