Pregnancy sickness or "morning sickness" is nausea, with or without vomiting, during pregnancy.

Morning sickness may occur at any time of the day, especially when the stomach is empty. It affects about one-third to one-half of all expectant women and is most common during the first three months of pregnancy. Some expectant mothers will not experience it until well into the second trimester and a few may never experience morning sickness throughout the pregnancy.

If the nausea and vomiting persist...