According to the American Medical Association, nearly 50 percent of women suffer nausea and vomiting during the first three months of pregnancy. It tends to be more severe early in the morning, but it can occur anytime during the day or night. Morning sickness usually occurs in the first trimester and ends around the third month of pregnancy. It's believed to be caused by the presence of certain hormones and changes in the way the body metabolizes carbohydrates. Most women experience only intermittent nausea and vomiting. To alleviate nausea, eat several small meals during the day because an empty stomach can bring on nausea. Avoid fatty foods, tobacco, and alcohol; they can make morning sickness worse. Eat foods high in carbohydrates, fiber, and protein. Drink plenty of fluids in-between meals to replace the fluids you're losing by vomiting, and to help neutralize stomach acids. It may also be helpful to keep a box of whole-grain crackers by your bed. Eating them about 20 minutes before you get up may reduce or prevent nausea. And if you can, it helps to get up and move about slowly in the morning, because rushing seems to make nausea worse. For more information on morning sickness, see a health care provider.