Nausea or vomiting during pregnancy is known as morning sickness. Although it is most common in the morning, it can occur at any time of day. It often occurs on an empty stomach or at night when women lay down.  

Morning sickness is very common during the first three months of pregnancy (the first trimester), typically peaking between the 2^nd and 12^th week. It usually disappears as the pregnancy progresses, and is normally gone by the fourth month. However, some women may experience nausea or vomiting through their entire pregnancy, and others will not experience it at all.

Although morning sickness does not occur in all pregnancies, the National Institutes of Health (NIH) estimate that most women develop some level of nausea and approximately one-third experience vomiting. Experts have not determined why some women experience morning sickness, while others do not. In addition, the level of morning sickness in each pregnancy is different. As a result, a woman cannot predict the level of morning sickness in future pregnancies from her experience in one pregnancy.

Some women have heard that if they do not experience morning sickness, they will be more likely to miscarry. However, there is no conclusive evidence linking morning sickness to a successful pregnancy. Many women who experience little or no morning sickness have a normal pregnancy and successful delivery of a healthy baby.

Morning sickness is unpleasant, but it usually does not cause any harm to the expectant mother or her fetus. Severe persistent vomiting, however, can cause complications. Hyperemesis gravidarum is a condition characterized by frequent and severe vomiting. It is a concern during pregnancy because it may lead to dehydration (a depletion of body fluids). It may also interfere with the weight gain needed to supply adequate nutrition to the mother and fetus.

Women should contact their obstetrician-gynecologist (ObGyn) when:

• Morning sickness does not improve with home remedies.
  
  
• There is a weight loss of more than two pounds.
  
  
• There is vomiting more than three times a day.
  
  
• There has been an inability to keep any food or liquid down.
  
  
• The vomit contains blood or looks like coffee grinds (this requires immediate medical attention).
  
  
• The nausea and vomiting continues into the fourth month of pregnancy.
  
  
• The urine is dark-colored.
  
  
• Urination is not occurring every four to six hours.
  
  
• The heart is racing or pounding.

Severe nausea and vomiting during pregnancy may indicate numerous conditions, including multiple pregnancy, and in rare cases, thyroid disorder or molar pregnancy (the growth of abnormal tissue in the uterus). To determine the cause of the condition and detect dehydration, the physician may perform a physical examination, including a pelvic examination. The patient’s blood pressure and pulse rate will be checked during the exam because an increased pulse rate and decreased blood pressure are signs of dehydration. The physician may perform additional tests to rule out other possible causes of nausea and vomiting, including abnormalities of the liver or gastrointestinal tract.

Blood tests and urine tests may be ordered to detect dehydration. Possible blood tests include a complete blood count (CBC) to detect increased levels of hematocrit (a sign of dehydration), and a chem-20 (a blood chemistry test). In addition, the woman’s urine will be analyzed for the presence of ketones and to determine the severity of dehydration. Ketones are produced when the body is forced to burn fat instead of glucose (blood sugar) for energy. They may be detectable in the urine or blood when nausea and vomiting prevent a woman from consuming enough calories.