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Only 12 hours after an egg cell is fertilized by a sperm cell, the egg cell starts to divide. As it continues to divide, it moves along the fallopian tube toward the uterus at about 1 inch per day.
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.
Thyroid conditions may make getting pregnant impossible.
Most women experience menopause in their 50s. However, in 1994, an Italian woman gave birth to a baby boy when she was 61 years old.
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.