For severe, persistent vomiting during pregnancy see the information on hyperemesis gravidarum .
Morning sickness is extremely common, occurring in about half of all pregnant women.
The problem usually begins during the first month of pregnancy and continues until the 14th to 16th week. Emotional stress , traveling, or some kinds of food may aggravate the problem. However, it may be caused by either hormonal changes or lower blood sugar during early pregnancy . Morning sickness usually stops after the first 3 or 4 months of pregnancy . Other than preventive measures, only time or the birth of the child will ultimately cure morning sickness.