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 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, 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
Morning sickness (most common)
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.
Prenatal vitamins with iron may cause nausea. Gastroesophageal reflux, often with heartburn, is common in pregnancy.
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, is not related to the pregnancy but is more common during pregnancy.
Rarely, severe, persistent vomiting results from a molar pregnancy (abnormal placental growth with or without a fetus due to an abnormally fertilized egg).
Other causes
Causes of nausea and vomiting unrelated to the pregnancy include
Gastroenteritis (an infection of the stomach or intestines)
Disorders of the abdomen such as appendicitis, a blockage in the intestine (intestinal obstruction), or inflammation of the gallbladder (cholecystitis)
Migraine headaches or more severe brain disorders )
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:
Vomiting that persists or that is worsening
Abdominal pain
Signs of dehydration, such as decreased urination, decreased sweating, increased thirst, a dry mouth, a rapid heart rate, and dizziness when standing up
Fever
No movement of the fetus if the pregnancy is 24 or more weeks
Confusion, weakness or numbness of one side of the body, speech or vision problems, or sluggishness
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 Some Causes and Features of Nausea and Vomiting During Early Pregnancy).
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
Some Causes and Features of Nausea and Vomiting During Early Pregnancy
Cause | Common Features | Diagnostic Approach† |
|---|---|---|
Related to the pregnancy (obstetric) | ||
Nausea and vomiting of pregnancy (morning sickness) | Mild nausea and vomiting that comes and goes and that occurs at varying times throughout the day, primarily during the 1st trimester | A doctor’s examination |
Frequent, persistent nausea and vomiting Inability to consume enough fluids, food, or both Usually signs of dehydration, such as decreased urination, decreased sweating, a dry mouth, increased thirst, a rapid heart rate, and dizziness when standing up Weight loss | Blood tests to check for signs of dehydration and chemical imbalances by measuring levels of electrolytes, blood urea nitrogen (BUN), creatinine, and liver enzymes Urine tests to measure ketones (produced when not enough food is consumed and the body breaks down fats for energy) | |
A molar pregnancy (abnormal placental growth with or without a fetus due to an abnormally fertilized egg) | A uterus that is larger than expected for the weeks of pregnancy No heartbeat or movement detected in the fetus Later in pregnancy, sometimes high blood pressure, swelling of the feet or hands, vaginal bleeding, or passage of tissue that resembles a bunch of grapes | Blood tests to measure human chorionic gonadotropin (hCG―a hormone produced by the placenta early in pregnancy) Ultrasonography of the pelvis |
Not related to the pregnancy | ||
A urinary tract infection or kidney infection (pyelonephritis) | An urge to urinate often (frequency), pain with urination (dysuria), or a compelling need to urinate immediately (urgency) With kidney infection, pain in the side or back and fever | Urine tests (urinalysis) and culture |
Vomiting that began suddenly, usually accompanied by diarrhea Sometimes recent contact with infected people or animals or recent consumption of undercooked, contaminated food or contaminated water | A doctor’s examination Sometimes, a stool sample | |
A blockage in the intestine (intestinal obstruction) | Nausea and vomiting that begins suddenly, usually in women who have had abdominal surgery in the past or who have abdominal cancer or an inguinal hernia Crampy pain and a swollen abdomen | X-rays Sometimes ultrasonography of the abdomen Sometimes CT (if x-ray and ultrasound results are unclear) |
* Features include symptoms and results of the doctor's examination. Features mentioned are typical but not always present. | ||
† In pregnant women with concerning symptoms, the doctor assesses maternal vital signs, does a physical examination, and evaluates the status of the fetus with a fetal heart rate monitor or ultrasound. | ||
CT = computed tomography. | ||
Testing
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.
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)
acupuncture, motion sickness bands, and hypnosis may help, as may switching from prenatal vitamins to children's chewable vitamins with folate.
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.
