Nausea and vomiting
Nausea and vomiting are also common in early pregnancy. Traditionally referred to as "morning sickness," the nausea and vomiting associated with early pregnancy can occur at any time of the day or night. Its typical onset is anywhere between the 2nd and 8th weeks of pregnancy. Most women who have morning sickness develop nausea and vomiting about one month after conception, but it may develop sooner in some women.
Elevations in estrogen that occur early in pregnancy are thought to slow the emptying of the stomach and may be related to the development of nausea. Accompanying the characteristic "morning sickness" may be cravings for, or aversions to, specific foods or even smells. It is not unusual for a pregnant woman to change her dietary preferences, often having no desire to eat previous "favorite" foods. In most women, nausea and vomiting begin to subside by the second trimester of pregnancy.