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Although puberty usually occurs in the early teenage years, the world's youngest parents were two Chinese children who had their first baby when they were 8 and 9 years of age.
More than 150,000 Americans killed by cardiovascular disease are younger than the age of 65 years.
Approximately 15–25% of recognized pregnancies end in miscarriage. However, many miscarriages often occur before a woman even knows she is pregnant.
During the twentieth century, a variant of the metric system was used in Russia and France in which the base unit of mass was the tonne. Instead of kilograms, this system used millitonnes (mt).
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.