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Fewer than 10% of babies are born on their exact due dates, 50% are born within 1 week of the due date, and 90% are born within 2 weeks of the date.
Bacteria have flourished on the earth for over three billion years. They were the first life forms on the planet.
Most childhood vaccines are 90–99% effective in preventing disease. Side effects are rarely serious.
The training of an anesthesiologist typically requires four years of college, 4 years of medical school, 1 year of internship, and 3 years of residency.
Astigmatism is the most common vision problem. It may accompany nearsightedness or farsightedness. It is usually caused by an irregularly shaped cornea, but sometimes it is the result of an irregularly shaped lens. Either type can be corrected by eyeglasses, contact lenses, or refractive surgery.