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Pregnant women usually experience a heightened sense of smell beginning late in the first trimester. Some experts call this the body's way of protecting a pregnant woman from foods that are unsafe for the fetus.
There are over 65,000 known species of protozoa. About 10,000 species are parasitic.
Human kidneys will clean about 1 million gallons of blood in an average lifetime.
Approximately one in three babies in the United States is now delivered by cesarean section. The number of cesarean sections in the United States has risen 46% since 1996.
Pope Sylvester II tried to introduce Arabic numbers into Europe between the years 999 and 1003, but their use did not catch on for a few more centuries, and Roman numerals continued to be the primary number system.