Nausea and vomiting are both common in early pregnancy. There is no evidence of fetal damage as a result of the nausea and vomiting. Nausea and vomiting can occur at any time of the day and may be constant.
The causes of nausea and vomiting in early pregnancy are unknown. Nausea in later pregnancy may be due to reflux oesophagitis and it responds to antacids.
Nausea and vomiting are very common in pregnancy but are usually mild and only require reassurance and advice. However, persistent vomiting and severe nausea can progress to hyperemesis gravidarum. Hyperemesis gravidarum refers to persistent and severe vomiting leading to fluid and electrolyte disturbance, marked ketonuria, nutritional deficiency and weight loss.
Hyperemesis gravidarum causes dehydration, electrolyte disturbance and ketosis. Without treatment, hyperemesis gravidarum may lead to central nervous system complications, liver failure and renal failure, but these complications are now rare in the developed world. See the section 'Hyperemesis gravidarum' at the end of this article.
- Nausea and vomiting are common in pregnancy, affecting up to 70% to 85% of pregnant women.
- Nausea and vomiting in pregnancy are more common in:
- Multiple pregnancy.
- History of previous hyperemesis gravidarum.
- It is less common with increasing maternal age.
- It tends to be a disease of Western society and is less common in developing countries, especially in rural communities.
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- Symptoms usually start between 4 and 7 weeks of gestation and resolve by 16 weeks in about 90% of women.
- Check for signs of dehydration and any possible underlying cause.
Other causes of nausea and vomiting should be considered:
- Gastrointestinal - eg, gastroenteritis, gastritis, cholecystitis, peptic ulceration, hepatitis, appendicitis, pancreatitis, gastrointestinal obstruction.
- Neurological - eg, migraine, raised intracranial pressure.
- Urinary tract infection.
- Ear, nose, and throat disease - eg, labyrinthitis, Ménière's disease, vestibular dysfunction.
- Drugs - eg, opioids, iron.
- Metabolic and endocrine disorders - eg, hypercalcaemia, diabetes, Addison's disease, uraemia (acute kidney injury, chronic kidney disease), and thyrotoxicosis.
- Psychological disorders - eg, bulimia.
- Pregnancy-associated conditions - eg, pre-eclampsia, gestational trophoblastic disease, twisted ovarian cyst, fatty liver of pregnancy.
- These are only required if there is a possible alternative diagnosis or in the assessment of the well-being of mother and fetus.
- In cases of hyperemesis gravidarum: renal function and electrolytes, LFTs, midstream urine and ultrasound (exclude multiple or molar pregnancy).
Most cases are mild and do not require treatment. Nausea and vomiting in pregnancy usually resolves spontaneously within 16 to 20 weeks and is not associated with a poor pregnancy outcome. However, persistent vomiting and severe nausea can progress to hyperemesis gravidarum if the woman is unable to maintain adequate hydration, and fluid and electrolyte balance. Nutritional status may be jeopardised.
- There is no research-based evidence on the effectiveness of dietary treatment.
- Advise the patient to rest; eat small, frequent meals that are high in carbohydrate and low in fat.
- Avoid any foods or smells that trigger symptoms.
Many different treatments are often used to help alleviate nausea and vomiting in pregnancy. A Cochrane review found that:
- Evidence regarding the effectiveness of P6 acupressure, auricular (ear) acupressure and acustimulation of the P6 point was limited.
- Acupuncture (P6 or traditional) showed no significant benefit to women in pregnancy.
- The use of ginger products may be helpful to women, but the evidence of effectiveness was limited and not consistent.
- There was only limited evidence from trials to support the use of pharmacological agents including pyridoxine (vitamin B6), and anti-emetic drugs to relieve mild or moderate nausea and vomiting.
- Anti-emetic drug treatment:
- This should only be given when symptoms are persistent, severe and preventing daily activities.
- Drug treatment options include cyclizine, metoclopramide, prochlorperazine, promethazine, chlorpromazine, domperidone and ondansetron (selective 5-hydroxytryptamine receptor antagonist), or combinations of these agents.
- Proton pump inhibitors and histamine H2-receptor antagonists may be used in women who also have dyspepsia and may be a useful adjunctive treatment.
- Ondansetron has shown benefits in patients with intractable hyperemesis gravidarum, with few side-effects and no reports of teratogenicity. One small study of women with severe disease found that ondansetron was no more effective than promethazine.
- There is no evidence that any one anti-emetic is better than another.
- Women with severe symptoms should be referred for fluid, electrolyte and vitamin replacement (usually intravenously). Nutritional support (enteral or parenteral) is needed in women who have intractable symptoms and weight loss, despite appropriate therapy.
- Indications for referral to secondary care include:
- Continued nausea and vomiting associated with ketonuria or weight loss (>5% body weight), despite oral anti-emetics.
- Continued nausea and vomiting and inability to keep down oral anti-emetics.
- Confirmed or suspected comorbidity (such as confirmed urinary tract infection and inability to tolerate oral antibiotics).
- Most cases are self-limiting and settle without complication as pregnancy progresses.
- However, nausea and vomiting may cause significant psychosocial difficulties, time off work and a restriction of domestic and leisure activities.
Different definitions of hyperemesis gravidarum exist, but the important features are intractable vomiting associated with weight loss of more than 5% of pre-pregnancy weight, dehydration, electrolyte imbalances, ketosis, and the need for admission to hospital.
- Hyperemesis gravidarum occurs in less than 1% of pregnancies.
- One study found that a moderate intake of water and adherence to a healthy diet that includes vegetables and fish before pregnancy are associated with a lower risk of developing hyperemesis gravidarum.
- There is evidence that hyperemesis gravidarum is associated with a higher female/male ratio.
- A Canadian study found that hyperthyroid disorders, psychiatric illness, previous molar pregnancy, pre-existing diabetes, gastrointestinal disorders and asthma were all risk factors for hyperemesis gravidarum, whereas maternal smoking and maternal age older than 30 were associated with decreased risk. Singleton female pregnancies, pregnancies with multiple male fetuses, and male and female combinations were associated with increased risk of hyperemesis gravidarum.
Vomiting that begins after 12 weeks of gestation is unlikely to be caused by hyperemesis gravidarum, and other pathological causes should always be considered before attributing nausea and vomiting in pregnancy to hyperemesis gravidarum. See 'Differential diagnosis', above.
- Advice, including dietary advice, and support: see 'Epidemiology', above.
- Fluid and electrolyte replacement:
- Women who are severely dehydrated and ketotic need to be assessed in secondary care, with intravenous fluid and electrolyte replacement (with normal saline or Hartmann's solution).
- Infusions of dextrose-containing fluids may precipitate Wernicke's encephalopathy.
- Fluid and electrolyte balance must be reassessed frequently.
- Potassium must be replaced appropriately.
- Nutritional support (enteral or parenteral) may be required.
- Vitamin supplements:
- Thiamine supplements should be given routinely - orally if tolerated, or intravenously - to all pregnant women admitted to hospital as a result of prolonged vomiting.
- Pyridoxine supplements should also be considered.
- Risk assessment for venous thrombosis and consideration of prophylactic low molecular weight heparin while dehydrated, unwell, or immobile are essential.
- Anti-emetic drugs: see 'management', above.
- Corticosteroids: may be used for intractable (failure to respond to conventional treatment) cases of severe hyperemesis gravidarum in secondary care.
In severe cases, dehydration, weight loss, electrolyte disturbance (eg, ketosis) and nutritional deficiency can occur. Hyperemesis gravidarum is rarely associated with death, but may lead to serious complications, including Wernicke's encephalopathy, central pontine myelinolysis and spontaneous oesophageal rupture.
- Weight loss (10-20% of body weight).
- Electrolyte abnormalities.
- Hyponatraemia, from persistent vomiting (leading to lethargy, headache, confusion, nausea, vomiting, and seizures), or overzealous correction of hyponatraemia, which can lead to central pontine myelinolysis.
- Hypokalaemia (skeletal muscle weakness, cardiac arrhythmias).
- Vitamin deficiencies: vitamin B1 deficiency (Wernicke’s encephalopathy, which may also be precipitated by high concentrations of dextrose); vitamin B12 and vitamin B6 deficiencies may cause anaemia and peripheral neuropathies.
- Mallory-Weiss tears of the oesophagus.
- Postpartum complications: persistence of symptoms and food aversions, postpartum gallbladder dysfunction, and symptoms of post-traumatic stress disorder.
- There is evidence that hyperemesis gravidarum is associated with a higher incidence of low birth weight (small for gestational age and premature babies).
- Little is known about the long-term health effects of babies born to mothers whose pregnancies were complicated by hyperemesis gravidarum.
Further reading & references
- Ogunyemi DA; Hyperemesis Gravidarum, Medscape, Aug 2011
- Nausea and vomiting in pregnancy, Prodigy (May 2008)
- Wegrzyniak LJ, Repke JT, Ural SH; Treatment of hyperemesis gravidarum. Rev Obstet Gynecol. 2012;5(2):78-84.
- Jarvis S, Nelson-Piercy C; Management of nausea and vomiting in pregnancy. BMJ. 2011 Jun 17;342:d3606. doi: 10.1136/bmj.d3606.
- Antenatal care: routine care for the healthy pregnant woman, NICE Clinical Guideline (March 2008)
- Matthews A, Dowswell T, Haas DM, et al; Interventions for nausea and vomiting in early pregnancy. Cochrane Database Syst Rev. 2010 Sep 8;(9):CD007575.
- Haugen M, Vikanes A, Brantsaeter AL, et al; Diet before pregnancy and the risk of hyperemesis gravidarum. Br J Nutr. 2011 Aug;106(4):596-602. Epub 2011 Apr 18.
- Veenendaal MV, van Abeelen AF, Painter RC, et al; Consequences of hyperemesis gravidarum for offspring: a systematic review and meta-analysis. BJOG. 2011 Oct;118(11):1302-13. doi: 10.1111/j.1471-0528.2011.03023.x. Epub 2011 Jul 12.
- Fell DB, Dodds L, Joseph KS, et al; Risk factors for hyperemesis gravidarum requiring hospital admission during pregnancy. Obstet Gynecol. 2006 Feb;107(2 Pt 1):277-84.
- Eliakim R, Abulafia O, Sherer DM; Hyperemesis gravidarum: a current review. Am J Perinatol. 2000;17(4):207-18.
|Original Author: Dr Colin Tidy||Current Version: Dr Colin Tidy||Peer Reviewer: Dr John Cox|
|Last Checked: 12/12/2012||Document ID: 2493 Version: 25||© EMIS|
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