Some pregnant women experience very bad nausea and vomiting. They might be sick many times a day and be unable to keep food or drink down, which can impact on their daily life. This excessive nausea and vomiting is known as hyperemesis gravidarum (HG), and often needs hospital treatment. Most women who experience morning sickness usually feel nauseous for a short time each day and may vomit once or twice. In more severe cases of morning sickness, nausea can last several hours each day and vomiting occurs more frequently.