Clinical Practice Guidelines Antenatal care - Module I

7.8 Nausea and vomiting

Page last updated: 02 April 2013

Nausea and vomiting are common in pregnancy, particularly in the first trimester, with the severity varying greatly among pregnant women. A range of non-pharmacological and pharmacological interventions can be used to assist in managing nausea and vomiting in pregnancy. Women may find these interventions useful, although the evidence for their effectiveness remains inconclusive.

7.8.1 Background

Nausea and vomiting in pregnancy ranges from mild discomfort to significant morbidity (King & Murphy 2009). Symptoms generally start around 4–9 weeks of pregnancy (Gadsby et al 1993). Nausea and vomiting due to other conditions (eg gastrointestinal, metabolic, neurologic or genitourinary) should always be excluded, particularly in women who report nausea or vomiting for the first time after 10 weeks (Koch & Frissora 2003).

The most severe form of nausea and vomiting in pregnancy is Hyperemesis gravidarum, which is intractable vomiting in early pregnancy, leading to dehydration and ketonuria severe enough to justify hospital admission and intravenous fluid therapy (Bottomley & Bourne 2009).

The cause of nausea and vomiting in pregnancy is not known but is probably multifactorial (Ebrahimi et al 2010). The rise in human chorionic gonadotrophin during pregnancy has been implicated; however, data about its association with nausea and vomiting are conflicting (Weigel & Weigel 1989).

Nausea and vomiting in pregnancy

  • Prevalence — Nausea is the most common gastrointestinal symptom of pregnancy, occurring in 80–85% of all pregnancies during the first trimester, with vomiting an associated complaint in approximately 52% of women (Whitehead et al 1992; Gadsby et al 1993). Retching (or dry heaving, without expulsion of the stomach’s contents) has been described as a distinct symptom that is increasingly measured separately to vomiting and nausea (Matthews et al 2010).
  • Timing — Most women report nausea and vomiting within 8 weeks of their LMP (94%), with over one third (34%) reporting symptoms within 4 weeks of their LMP (Whitehead et al 1992; Gadsby et al 1993). Most women (87–91%) report cessation of symptoms by 16–20 weeks of pregnancy. Although nausea and vomiting is commonly referred to as ‘morning sickness’, only 11–18% of women report having nausea and vomiting confined to the mornings (Whitehead et al 1992; Gadsby et al 1993).
  • Hyperemesis gravidarum — This condition is much less common, affecting 0.3–1.5% of women (Bottomley & Bourne 2009). Symptoms typically start between 5 and 10 weeks pregnancy and resolve by 20 weeks. However, up to 10% of women will continue to vomit throughout the pregnancy. The hospital admission rate for the condition falls from 8 weeks onwards (Bottomley & Bourne 2009).

Impact of nausea and vomiting in pregnancy

Although distressing and debilitating for some women, nausea and vomiting do not appear to have a negative impact on pregnancy outcomes. A systematic review of observational studies found a reduced risk of miscarriage associated with nausea and vomiting (odds ratio [OR] 0.36; 95% confidence interval [CI] 0.32–0.42) and conflicting data regarding reduced risk for perinatal mortality (Weigel & Weigel 1989).No studies have reported an association between nausea and vomiting in pregnancy and teratogenicity (Klebanoff & Mills 1986).

However, despite reassurance that nausea and vomiting do not have harmful effects on pregnancy outcomes, these symptoms can have a severe impact on a pregnant woman’s quality of life. Two observational studies have reported on the detrimental impact that nausea and vomiting may have on women’s day-to-day activities, including interfering with household activities, affecting relationships, greater use of healthcare resources and time off work (Smith et al 2000; Attard et al 2002).
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7.8.2 Managing nausea and vomiting in pregnancy

Interventions for nausea and vomiting that do not require prescription include ginger, acupressure, acupuncture and vitamin B6. Prescribed treatments include antihistamines and phenothiazines.'

Summary of the evidence

The systematic review conducted to inform these Guidelines identified additional evidence that was consistent with the NICE guidelines. The highest quality study, a Cochrane review (Matthews et al 2010) examined 27 trials of interventions including acustimulation, acupuncture, ginger, vitamin B6 and several antiemetic medicines. Systematic review of studies in this area is complicated by the heterogeneity of studies and limited information on outcomes (Matthews et al 2010).

The available evidence suggests the following.
  • Ginger — While small RCTs have found reduced severity of nausea and vomiting with ginger products (syrup or capsules) (Murphy 1998; Vutyavanich et al 2001; Keating & Chez 2002), there is limited and inconsistent evidence of their effectiveness, although there is evidence that their use may be helpful to women (Matthews et al 2010). Dosages of up to 250 mg four times a day appear to be safe (Vutyavanich et al 2001).
  • Acupressure, acustimulation and acupuncture — While some evidence from systematic reviews of RCTs (Murphy 1998; Vickers 1996) supports the use of P6 acupressure and it appears to be safe in pregnancy (Smith et al 2000), the evidence on the effectiveness of P6 acupressure, auricular acupressure and acustimulation of the P6 point is inconsistent and limited and there appears to be no significant benefit of acupuncture (P6 or traditional) (Matthews et al 2010).
  • Pyridoxine (vitamin B6) — There is limited evidence to support the use of pyridoxine (Matthews et al 2010) and concerns about possible toxicity at high doses.
  • Antihistamines — A meta-analysis of 12 RCTs that compared antihistamines pyridoxine with placebo or no treatment found a significant reduction in nausea in the treated group (OR 0.17; 95% CI 0.13–0.21)(Jewell & Young 2001). A systematic review of three RCTs (n=389) found that phenothiazines reduced nausea or vomiting when compared with placebo (relative risk [RR] 0.31; 95% CI 0.24–0.42) (Mazzotta & Magee 2000), although different phenothiazines were grouped and one of the trials recruited women after the first trimester. The bulk of the evidence demonstrates no association between birth defects and phenothiazines (n=2,948; RR 1.03; 95% CI 0.88–1.22)(Mazzotta & Magee 2000; Attard et al 2002).
  • Other pharmacological treatments — Antiemetic medicines are more likely to have a place in treatment of severe symptoms and the intractable nausea and vomiting of Hyperemesis gravidarum than in the relief of mild or moderate nausea and vomiting (Matthews et al 2010).
It is currently not possible to identify with certainty interventions for nausea and vomiting in early pregnancy that are both safe and effective (Matthews et al 2010). As nausea and vomiting mostly resolves within 16 to 20 weeks with no harm to the pregnancy, prescribed treatment in the first trimester is usually not indicated unless the symptoms are severe and debilitating (BMA 2003).

Practice point

k. Women who experience nausea and vomiting in pregnancy can be advised that, while it may be distressing, it usually resolves spontaneously by 16 to 20 weeks pregnancy and is not generally associated with a poor pregnancy outcome.

Discontinuing iron

Iron supplementation may be an aggravating factor in nausea and vomiting. The systematic review conducted for these Guidelines identified a prospective cohort study (Gill et al 2009) in which 63 of 97 (p =0.001) women with severe nausea qualitatively reported an improvement in symptoms after discontinuing iron-containing antenatal multivitamins. If multivitamins are discontinued, consideration should be given to ensuring folate and iodine intake remain sufficient.

Practice point

l. Discontinuing iron-containing multivitamins for the period that women have symptoms of nausea and vomiting may improve symptoms.

Oral health

Nausea and vomiting have the potential to affect oral health and women should be given advice on how to minimise these effects (see Section 10.5).

7.8.3 Practice summary — managing nausea and vomiting

When — At the first contact with all women and at subsequent contacts for women who report nausea and vomiting
Who — Midwife; GP; obstetrician; Aboriginal and Torres Strait Islander health worker; multicultural health worker; dietitian; pharmacist
  • Inform women that nausea and vomiting is not associated with adverse effects — Explain that nausea and vomiting is common in pregnancy, is not necessarily confined to the morning and is likely to lessen by week 16.
  • Provide lifestyle/diet advice — Acknowledge that nausea and vomiting affects quality of life, and suggest tips on managing nausea and vomiting, including drinking plenty of fluids, eating little and often during the day, getting plenty of rest and avoiding fatty or spicy food. Avoiding iron-containing multivitamins while nausea and vomiting are present may also help.
  • Discuss non-pharmacological and pharmacological treatments — If the woman asks about treatments for nausea and vomiting, suggests interventions that may help and are thought to be safe, beginning with nonpharmacological approaches (e.g. travel sickness bands). The saftey and effectiveness of antiemetics should be discussed with women with more severe symptoms who choose to consider medication.
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7.8.4 Resources

Health professionals

Arsenault M-Y, Lane CA (2002) The Management of Nausea and Vomiting of Pregnancy. Clinical Practice Guideline no.120.
Society of Obstetricians and Gynaecologists of Canada. J Obstet Gynaecol Can 24(10): 817–23.


RACGP Family Doctor Home Advisor. (This website link was valid at the time of submission)
SOGC Women’s Health Information — For more information please visit Society of Obstetricians and Gynaecologists website.

7.8.5 References

Attard CL, Kohli MA, Coleman S et al (2002) The burden of illness of severe nausea and vomiting of pregnancy in the United States. Am J Obstet Gynecol 186: S220–27.

BMA (2003) British National Formulary. British Medical Association. London: Royal Pharmaceutical Society of Great Britain, pp 439–40.

Bottomley C & Bourne T (2009) Management strategies for hyperemesis. Best Pract Res Clin Obstet Gynaecol 23(4): 549–64.

Ebrahimi N, Maltepe C, Einarson A (2010) Optimal management of nausea and vomiting of pregnancy. Int J Women’s Health 2: 241–48.

Gadsby R, Barnie-Adshead AM, Jagger C (1993) A prospective study of nausea and vomiting during pregnancy. Brit J General Practice 43: 245–48.

Gill SK, Maltepe C, Koren G (2009) The effectiveness of discontinuing iron-containing prenatal multivitamins on reducing the severity of nausea and vomiting of pregnancy. J Obstet Gynaecol 29(1): 13–16.

Jewell D & Young G (2001) Interventions for nausea and vomiting in early pregnancy. Cochrane Database of Systematic Reviews 2001;(2).

Keating A & Chez RA (2002) Ginger syrup as an antiemetic in early pregnancy. Alt Ther Health Med 8: 89–91.

King TL & Murphy PA (2009) Evidence-based approaches to managing nausea and vomiting in early pregnancy. J Midwif Womens Health 54(6): 430–44.

Klebanoff MA & Mills JL (1986) Is vomiting during pregnancy teratogenic? Brit Med J 292: 724–26.

Koch KL & Frissora CL (2003) Nausea and vomiting during pregnancy. Gastroenterol Clin North Am. 32: 201–34.

Matthews A, Dowswell T, Haas DM et al (2010) Interventions for nausea and vomiting in early pregnancy. Cochrane Database of Systematic Reviews 2010, Issue 9. Art. No.: CD007575. DOI: 10.1002/14651858.CD007575.pub2.

Mazzotta P & Magee LA (2000) A risk–benefit assessment of pharmacological and nonpharmacological treatments for nausea and vomiting of pregnancy. Drugs 59: 781–800.

Murphy PA (1998) Alternative therapies for nausea and vomiting of pregnancy. Obstet Gynecol 91: 149–55.

Smith C, Crowther C, Beilby J et al (2000) The impact of nausea and vomiting on women: a burden of early pregnancy. Aust NZ J Obstet Gynaecol 40: 397–401.

Vickers AJ (1996) Can acupuncture have specific effects on health? A systematic review of acupuncture antiemesis trials. J Royal Soc Med 89: 303–11.

Vutyavanich T, Kraisarin T, Ruangsri R (2001) Ginger for nausea and vomiting in pregnancy: randomized, doublemasked, placebo controlled trial. Obstet Gynecol 97: 577–82.

Weigel RM & Weigel MM (1989) Nausea and vomiting of early pregnancy and pregnancy outcome. A meta-analytical review. Brit J Obstet Gynaecol 96: 1312–18.

Whitehead SA, Andrews PL, Chamberlain GV (1992) Characterisation of nausea and vomiting in early pregnancy: a survey of 1000 women. J Obstet Gynaecol 12: 364–69.
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