Pregnancy Morning Sickness or Hyperemesis gravidarum, the medical name for excessive vomiting in pregnancy (hyper means "over"; emesis means "vomiting"; gravidarum means "pregnant state"), affects about one in every 300 pregnant women. This condition is defined as vomiting that is frequent, persistent, and severe. If not treated, hyperemesis can keep the mother from getting the nutrition and fluids she needs. If nausea during pregnancy persists long enough, it can also threaten the fetus.
The causes of pregnancy morning sickness are not known with certainty, but it appears to be linked to higher-than-usual levels of the hormones hCG and estrogen. It is more common in first pregnancies, young women, and women carrying multiple fetuses.
Before treating you for hyperemesis, your doctor will first want to rule out other possible causes of the vomiting, such as gastrointestinal disorders, thyroid problems, or other possible issues. Mild cases are treated with a change in diet, additional rest and medications. More severe cases often require a stay in the hospital so that the mother can receive fluid and nutrition through an intravenous line.
If you have nausea and vomiting so severe that you cannot keep any food down, or if it persists well into the second trimester, contact your doctor. Do so right away if vomiting is accompanied by pain or fever.