Most pregnant women report having some nausea in their first trimester, and many also report vomiting, according to "Gastrointestinal and Liver Disease." Nausea and vomiting during pregnancy is usually mild, and most women are still able to eat food and drink fluids. Persistent, severe vomiting during pregnancy, also known as hyperemesis gravidarum, is much less common. Though its cause is unknown, hyperemesis gravidarum is associated with fluid losses and mineral imbalances that often require medical intervention.
Vomiting During Pregnancy
Sixty percent to 70 percent of pregnant women report having some nausea in their first trimester, and more than 40 percent report vomiting. Vomiting usually begins around the fifth week of pregnancy and usually resolves on its own by week 20. Symptoms are usually worse in the morning, which is why vomiting during pregnancy is often called "morning sickness." Although nausea and vomiting may vary from mild to severe, most women are still able to eat regular meals and so do not experience fluid or mineral deficiencies.
Hyperemesis Gravidarum
Severe, persistent vomiting is called hyperemesis gravidarum. It occurs in 2 percent or fewer of all pregnancies and often requires medical intervention. Repeated bouts of vomiting can lead to large fluid losses and mineral imbalances in addition to weight loss of about 5 percent of pregnancy weight. The condition is defined by the presence of ketone bodies in the urine. Your body makes these compounds to fuel your cells when your diet does not supply sufficient calories.
Causes
The specific cause of hyperemesis gravidarum is unknown. Likely contributing factors include elevated levels of the hormones estrogen and progesterone, as well as hyperthyroidism. Infection with H. pylori, the bacteria that causes ulcers, may also contribute to the condition. If you are pregnant with a girl or with twins, or if you have a family history of hyperemesis gravidarum, your risk of developing the condition is slightly increased.
Mineral Deficiencies
The vomiting in hyperemesis gravidarum can be so severe that patients are unable to take in food or fluids for hours, even days. Persistent vomiting also leads to large quantities of fluid lost. As a result, low blood pressure and rapid heart rate can develop, in addition to weight loss. Because your stomach contents are rich in sodium and potassium, severe vomiting can lead to markedly low levels of these important minerals. Low blood sodium causes symptoms including nausea and vomiting, which can further worsen the emesis. Low potassium in the blood is associated with weakness and fatigue.
Treatment
Treatment for hyperemesis gravidarum is supportive and consists of fluid and mineral replacement. If you suffer symptoms such as weight loss, low blood pressure or rapid heart rate, hospital admission may be required. In the hospital, patients receive intravenous fluid and electrolyte replacement, with sodium chloride and potassium, according to "Current Medical Diagnosis and Treatment, 2011." The goal is to control vomiting, often with medications such as Benadryl. Vitamin B-6 and ginger have also proven useful. Patients should eat multiple small meals that include salty snacks and bananas, a source of potassium, and avoid an empty stomach, which may trigger nausea.
References
- "Current Medical Diagnosis and Treatment"; Stephen J. McPhee; 2011
- "Sleisenger and Fordtran's Gastrointestinal and Liver Disease"; Mark Feldman, M.D.; 2002
- MayoClinic.com: Low potassium
- MayoClinic.com: Hyponatremia
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