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Nausea and Vomiting During Early Pregnancy

(Morning Sickness)


Emily E. Bunce

, MD, Wake Forest School of Medicine;

Robert P. Heine

, MD, Wake Forest School of Medicine

Reviewed/Revised Jul 2023
Topic Resources

Pregnancy frequently causes nausea and vomiting. It is often called "morning sickness," but it can occur any time of day or night. This type of nausea and vomiting usually starts around 5 weeks of pregnancy and is at its worst at about 9 weeks. It usually disappears by about 16 to 18 weeks. Symptoms vary from mild to severe.

Hyperemesis gravidarum Hyperemesis Gravidarum Hyperemesis gravidarum is extremely severe nausea and excessive vomiting during pregnancy. Women with hyperemesis gravidarum, unlike women with ordinary morning sickness, lose weight and become... read more is a severe, persistent form of pregnancy-related vomiting. Women with hyperemesis gravidarum vomit so much that they lose weight and become dehydrated. Such women may not consume enough food to provide their body with energy. Then the body breaks down fats, resulting in a buildup of waste products (ketones) called ketosis. Ketosis can cause fatigue, bad breath, dizziness, and other symptoms. Women with hyperemesis gravidarum often become so dehydrated that the balance of electrolytes Overview of Electrolytes More than half of a person's body weight is water. Doctors think about water in the body as being restricted to various spaces, called fluid compartments. The three main compartments are Fluid... read more , needed to keep the body functioning normally, is upset. If women vomit occasionally but gain weight and are not dehydrated, they do not have hyperemesis gravidarum.

Causes of Nausea and Vomiting During Pregnancy

Usually, nausea and vomiting during pregnancy are related to the pregnancy. However, sometimes they result from a disorder unrelated to the pregnancy.

Pregnancy-related causes

The most common causes of nausea and vomiting related to pregnancy are

The causes of morning sickness and hyperemesis gravidarum are unclear. It is possible that these symptoms are related to a rapid increase in the levels of two hormones in early pregnancy: human chorionic gonadotropin (hCG), which is produced by the placenta early in pregnancy, and estrogen, which helps maintain the pregnancy. Also, hormones such as progesterone may slow the movement of the digestive system, possibly contributing to nausea and vomiting.

Occasionally, the corpus luteum, an ovarian cyst that is normal in early pregnancy, may cause the ovary to twist around the ligaments and tissues that support it, cutting off the ovary's blood supply. This disorder, called adnexal torsion Adnexal Torsion Adnexal torsion is twisting of the ovary and sometimes the fallopian tube, interrupting or cutting off the blood supply of these organs. Twisting causes sudden, severe pain and often nausea... read more , is not related to the pregnancy but is more common during pregnancy.

Other causes

Causes of nausea and vomiting unrelated to the pregnancy include

However, these disorders usually cause other symptoms that are more prominent, such as abdominal pain or headaches.

Evaluation of Nausea and Vomiting During Pregnancy

Doctors first try to determine whether nausea and vomiting are caused by a serious disorder. Morning sickness and hyperemesis gravidarum are diagnosed only after other causes are ruled out.

Warning signs

In pregnant women who are vomiting, the following symptoms are cause for concern:

When to see a doctor

Women with warning signs should see a doctor right away.

Women without warning signs should talk to their doctor. The doctor can help them decide whether and how quickly they need to be seen based on the nature and severity of their symptoms. Women who have mild to moderate nausea and vomiting, have not lost weight, and are able to keep some liquids down may not need to see a doctor unless their symptoms worsen.

What the doctor does

Doctors ask about symptoms and the medical history and do a physical examination. What they find during the history and physical examination often suggests a cause and the tests that may need to be done (see table ).

Doctors ask about the vomiting:

  • When it started

  • How long it lasts

  • How many times a day it occurs

  • Whether anything relieves or makes it worse

  • How much there is

  • If food and/or liquids are staying down

The doctor asks the woman if she has other symptoms, particularly abdominal pain, diarrhea, and constipation, and how her symptoms have affected her and her family—whether she can work and care for herself and her children. The doctor also asks about vomiting in previous pregnancies, about previous abdominal surgery, and use of medications that may contribute to vomiting.

During the physical examination, doctors do a routine prenatal evaluation, including measuring the woman's vital signs and evaluating the fetus. They look for signs of serious disorders, such as blood pressure that is too low or too high, fever, or abdominal tenderness.

This information helps doctors determine whether vomiting results from the pregnancy or another, unrelated disorder. For example, vomiting is more likely to be due to pregnancy if

  • Symptoms begin during the 1st trimester.

  • Symptoms last or recur over several days to weeks.

  • The woman does not have abdominal pain.

  • There are no symptoms involving other organ systems.

Vomiting probably results from a disorder unrelated to the pregnancy if it

  • Began after the 1st trimester

  • Is accompanied by abdominal pain, diarrhea, or both



Doctors often use a handheld Doppler ultrasound device, placed on the woman's abdomen, to check for a heartbeat in the fetus. If no heartbeat is detected, doctors do a pelvic ultrasonography to evaluate the fetus and rule out an abnormality. Rarely, nausea and vomiting during pregnancy may be a symptom of a molar pregnancy Molar Pregnancy A molar pregnancy (hydatidiform mole) and other types of gestational trophoblastic disease are growth of an abnormal fertilized egg or an overgrowth of tissue from the placenta. Women with a... read more .

If the woman is vomiting often or appears dehydrated or if a molar pregnancy is possible, tests are usually done. Which tests are done depend on the cause doctors suspect:

  • Hyperemesis gravidarum: Urine tests (to measure ketone levels) and possibly blood tests (to measure electrolyte levels and other substances)

  • A molar pregnancy: Ultrasonography of the pelvis

  • A disorder unrelated to the pregnancy: Tests specific for that disorder

Treatment of Nausea and Vomiting During Pregnancy

If the symptoms seem to be common nausea and vomiting of pregnancy (morning sickness), some changes in diet or eating habits may help:

  • Drinking or eating small amounts more frequently (5 or 6 small meals a day)

  • Eating before getting hungry

  • Eating only bland foods, such as bananas, rice, applesauce, and dry toast (called the BRAT diet)

  • Keeping crackers by the bed and eating one or two before getting up in the morning

  • Drinking carbonated drinks (sodas)

If needed, medications to relieve nausea (antiemetic drugs) are given. Doctors choose medications that appear to be safe during early pregnancy. Vitamin B6 is used first. If it is ineffective, another drug (doxylamine, metoclopramide, ondansetron, or promethazine) may also be given.

If vomiting results in dehydration, the woman may be given fluids intravenously (directly into her vein). The fluids usually contain sugar (glucose) and include electrolytes and vitamins as needed. If vomiting is severe and persists, she is hospitalized and continues to be given fluids containing any needed supplements. She is also given antiemetics by mouth, injection, or suppository. After vomiting has subsided, she is given fluids by mouth. If she can keep these fluids down, she can begin eating frequent, small portions of bland foods. The size of the portions is increased as the woman can tolerate more food.

If nausea and vomiting is due to a disorder unrelated to the pregnancy, that disorder is treated.

Key Points

  • Usually, nausea and vomiting during pregnancy do not cause weight loss or other problems, and they resolve before or during the 2nd trimester.

  • Hyperemesis gravidarum, a severe, persistent form of pregnancy-related vomiting, is less common and can cause dehydration and weight loss.

  • Nausea and vomiting may be due to disorders not related to pregnancy, such as gastroenteritis, a urinary tract infection, or, rarely, a blockage in the intestine.

  • Modifying the diet may help relieve mild nausea and vomiting that are related to pregnancy.

  • If women with hyperemesis gravidarum become dehydrated, they may need to be given fluids intravenously.

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