The nausea and vomiting of early pregnancy were written about as early as 2000 B.C. Unfortunately, the ancient Egyptians didn't have a cure for the condition, either.
More than half of American women will suffer from nausea, vomiting, or both during the first three months (also known as the first trimester) of pregnancy, according to the March of Dimes. The severity and occurrence, however, vary not only from woman to woman, but from pregnancy to pregnancy in the same individual.
Some women never have even the slightest touch of queasiness. Some are ill in the morning and recover by lunch. And some stay sick all day for days on end, wondering why it's called "morning sickness" when it lasts 24 hours.
No one knows what causes morning sickness. It is less common among Eskimos and native African tribes than in Western civilizations. But today's doctors emphasize it's not psychological, as was once believed.