INTRODUCTION

Nausea and vomiting of pregnancy commonly occur between 5 and 18 weeks of pregnancy. Between 50 and 90 percent of women have some degree of nausea, with or without vomiting. The severity of these symptoms can vary.

"Morning sickness" is the term often used to describe mild nausea and vomiting while "hyperemesis gravidarum" is the term used to describe a more severe condition. Hyperemesis may cause you to vomit multiple times throughout the day, lose weight, and usually requires treatment in the hospital.

This article discusses treatments available for nausea and vomiting during pregnancy. A more detailed article is available by subscription. (See "Clinical features and diagnostic evaluation of nausea and vomiting of pregnancy (hyperemesis gravidarum and morning sickness)" and "Treatment of nausea and vomiting of pregnancy (hyperemesis gravidarum and morning sickness)".)

MORNING SICKNESS VERSUS HYPEREMESIS

Morning sickness — Nausea and vomiting often develop by five to six weeks of pregnancy. The symptoms are worst around nine weeks, and typically improve by 16 to 18 weeks of pregnancy. However, symptoms continue until the third trimester in 15 to 20 percent of women and until delivery in 5 percent of women [1]. Although mild pregnancy-related nausea and vomiting is often called "morning sickness," you may feel sick at any time of day and many women (80 percent) feel sick throughout the day.

Interestingly, women with mild nausea and vomiting during pregnancy experience fewer miscarriages and stillbirths than women without these symptoms.

Hyperemesis gravidarum — Hyperemesis gravidarum is the term used to describe more severe nausea and vomiting during pregnancy. Women with hyperemesis often vomit every day and may lose more than 5 percent of their pre-pregnancy body weight. In most cases, women with hyperemesis gravidarum will have blood and urine tests that show evidence of dehydration.

CAUSE OF NAUSEA AND VOMITING IN PREGNANCY

The cause of pregnancy-related nausea and vomiting is not clear. Several theories have been proposed, although none have been definitively proven. Increased hormone levels, slowed movement of the stomach contents, and psychological factors are among the more common theories.

Some women are more likely to develop nausea and vomiting of pregnancy, including women who:

• Developed these symptoms in a previous pregnancy
• Experience nausea and vomiting while taking estrogen (for example, in birth control pills), have menstrual migraines, or after being exposed to certain smells or tastes
• Experience motion sickness

WHEN TO SEEK HELP

Many women, especially those with mild to moderate nausea and/or vomiting, do not need to see a healthcare provider for treatment of nausea and vomiting. The suggestions below may help to reduce symptoms and prevent dehydration. (See 'Treatment of nausea and vomiting in pregnancy' below.)

If possible, you should schedule your first prenatal visit before 11 weeks of pregnancy to allow time for routine testing to be scheduled. (See "Patient information: Should I have a screening test for Down syndrome during pregnancy?".)

Women with more severe nausea and vomiting sometimes need to be evaluated by their primary care or obstetrical doctor or nurse. Seek help if you have one or more of the following:

• Signs of dehydration, including infrequent urination, dark-colored urine, or dizziness with standing
• Vomiting repeatedly throughout the day, especially if you see blood in the vomit
• Abdominal or pelvic pain or cramping
• If you are unable to keep down any food or drinks for more than 12 hours
• You lose more than 5 pounds (2.3 kg)

One or more tests may be recommended to investigate the cause and determine the severity of the nausea and vomiting, including blood tests, urine tests, or an ultrasound.

TREATMENT OF NAUSEA AND VOMITING IN PREGNANCY

The treatment of pregnancy-related nausea and vomiting aims to help you feel better and allow you to eat and drink enough so that you do not lose weight.

Treatment may not totally eliminate your nausea and vomiting. You may need to try several types of treatment over a period of weeks before finding what works best for you. Fortunately, symptoms generally resolve by mid-pregnancy, even if you do not use any treatment. (See "Treatment of nausea and vomiting of pregnancy (hyperemesis gravidarum and morning sickness)".)

Dietary changes — Try eating before or as soon as you feel hungry to avoid an empty stomach, which may aggravate nausea. Eat snacks frequently and have small meals that are high in protein or carbohydrates and low in fat. Drink cold, clear, and carbonated or sour fluids (eg, ginger ale, lemonade) and drink these in small amounts between meals. Smelling fresh lemon, mint, or orange or using an oil diffuser with these scents may also be useful.

Avoid triggers — One of the most important treatments for pregnancy-related nausea and vomiting is to avoid odors, tastes, and other activities that trigger nausea. Eliminating spicy foods helps some women. Other examples of triggers include:

• Stuffy rooms
• Odors (eg, perfume, chemicals, coffee, food, smoke)
• Heat and humidity
• Noise
• Visual or physical motion (eg, flickering lights, driving)
• Being tired

Brushing teeth after eating may help prevent symptoms. Avoid lying down immediately after eating and avoid quickly changing positions.

If you take a prenatal vitamin with iron and this worsens your symptoms, try taking them at bedtime. If symptoms persist, stop the vitamins temporarily. If you stop taking your prenatal vitamin, take a supplement that contains at least 400 micrograms of folic acid until you are at least 14 weeks pregnant to reduce the risk of birth defects.

Medications — Medications that reduce nausea and vomiting are effective in some women and are safe to take during pregnancy. None of the medications discussed below are known to be harmful.

• Vitamin B6 and doxylamine — Vitamin B6 supplements (10 to 25 mg three to four times per day) can reduce symptoms of mild to moderate nausea, but do not usually help with vomiting.

Doxylamine is a medication that can reduce vomiting, and may be combined with vitamin B6. Doxylamine is available in the United States in some non-prescription sleep aids (eg, Unisom®, Good Sense Sleep Aid®) and as a prescription antihistamine chewable tablet (Aldex AN).

In the United States, one-half of a 25 mg doxylamine tablet or two of the chewable 5 mg tablets can be used to reduce vomiting, although doxylamine is not "officially" approved for this purpose. Some healthcare providers also prescribe vitamin B6 supplements (10 to 25 mg three to four times per day) to take with it. Outside the United States, combinations of vitamin B6 and doxylamine are available (eg, Diclectin® in Canada).

Combinations of vitamin B6 and doxylamine were previously available in the United States in a prescription medication called Bendectin®. Bendectin® was voluntarily withdrawn from the market in 1983 due to lawsuits claiming that the medication caused birth defects. However, subsequent studies confirmed that the medication is safe, effective, and does not increase the risk of birth defects [2].

• Antihistamines and other anti-nausea medications — Antihistamines and other anti-nausea medications are safe and effective treatments for pregnancy-related nausea and vomiting. The following medications may be recommended:

• - Promethazine (Phenergan®)— — Promethazine is available in pill, injectable solution, or rectal suppository form. It is usually taken every four hours, and may cause drowsiness and dry mouth. Rare side effects include muscle contractions that cause twisting or jerking movements.
• - Metoclopramide (Reglan®)— — Metoclopramide speeds emptying of the stomach and may help to reduce nausea and vomiting. It is usually taken by mouth or injection every six hours (four times per day, 30 minutes before eating and at bedtime).
• - Ondansetron (Zofran®)— — Ondansetron is an anti-nausea medication that is usually taken by mouth or injection every eight to 12 hours. Ondansetron is one of the most expensive anti-nausea medications (approximately $500 for 30 pills in the United States) and it may not be covered by some insurance plans.

Fluids and nutrition — If you are unable to hold down food or liquids, you may be treated with intravenous (IV) fluids. This may be done in your doctor or nurse's office or in the hospital, depending upon the severity of your vomiting. For a short time, you may be advised not to eat or drink anything, to allow the gut to rest. You can slowly begin to eat and drink again as you begin to feel better, usually within 24 to 48 hours.

If you continue to lose weight despite treatment, your doctor may consider other forms of feeding, such as the use of a nasogastric tube (a tube that is inserted through your nose into the stomach) or supplemental nutrition through an IV line.

Complementary treatments — The following treatments may be useful when used with the treatments described above.

• Acupuncture and acupressure — Acupressure wristbands (picture 1) and acupuncture have become a popular treatment for nausea and vomiting caused by pregnancy, motion sickness, and other causes. Studies have not shown these wristbands to be more effective than sham (fake, look-alike) wristbands [3], although some women find them helpful. Acupuncture and acupressure have no known harmful side effects.
• Hypnosis — Hypnosis has been reported to be helpful in some people. Counseling may be helpful for women with anxiety.
• Ginger — Powdered ginger may help to relieve nausea and vomiting in some women. However, further studies are needed to confirm that this treatment is both safe and effective. Until more data are available, we suggest the use of ginger containing foods (eg, ginger lollipops, ginger ale) for mild nausea and vomiting.

OUTCOME

Most women with pregnancy-related nausea and vomiting recover completely without any complications. Women with mild to moderate vomiting often gain less weight during early pregnancy. This is rarely a concern for the baby unless the mother was very underweight before pregnancy (at least 10 percent under the ideal body weight).

Normal weight gain during pregnancy depends upon your pre-pregnancy weight, but is usually between 14 and 25 pounds (6.5 to 11 kilograms).

In women with severe nausea and vomiting (hyperemesis gravidarum) who are hospitalized multiple times and who do not gain weight normally during pregnancy, there is a small risk that the baby will be underweight or small.

Women who have hyperemesis gravidarum in one pregnancy are at risk of severe nausea and vomiting in future pregnancies. The risk is between 15 and 20 percent. Women who do not have severe nausea and vomiting in the first pregnancy are unlikely to have it in future pregnancies [4].

WHERE TO GET MORE INFORMATION

Your healthcare provider is the best source of information for questions and concerns related to your medical problem.

This article will be updated as needed every four months on our web site (www.uptodate.com/patients).

Related topics for patients, as well as selected articles written for healthcare professionals, are also available. Some of the most relevant are listed below.

Patient level information

Patient information: A guide to pregnancy
Patient information: Should I have a screening test for Down syndrome during pregnancy?

Professional level information

Approach to the adult with nausea and vomiting
Characteristics of antiemetic drugs
Clinical features and diagnostic evaluation of nausea and vomiting of pregnancy (hyperemesis gravidarum and morning sickness)
Treatment of nausea and vomiting of pregnancy (hyperemesis gravidarum and morning sickness)
Patient information: A guide to pregnancy

The following organizations also provide reliable health information.

• National Library of Medicine

      (www.nlm.nih.gov/medlineplus/ency/article/001499.htm, available in Spanish)

• Society of Obstetricians and Gynecologists of Canada

      (www.sogc.org/health/pregnancy-nausea_e.asp)

• Organization of Teratology Information Specialists

      (http://otispregnancy.org/otis_fact_sheets.asp, available in Spanish)

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