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Severe nausea and vomiting in pregnancy


Key learning points:

- The difference between mild, moderate and severe pregnancy sickness and hyperemesis gravidarum

- Understanding the possible causes of the condition

- What support and treatment to offer to women suffering with pregnancy sickness or hyperemesis gravidarium

Nausea and vomiting in pregnancy (NVP) is very common and ranges in severity from mild to severe. Hyperemesis gravidarum (HG) is at the extreme end of the spectrum. HG is a severe and potentially life-threatening condition which can have a profound affect on the sufferer's health and wellbeing. Primary care nurses may be the first contact for women suffering, and seeking help before their first midwife appointment. Treatment and referral should be initiated where appropriate.

How many women get NVP and HG?

About 75% to 80% of pregnant women have some degree of NVP.1 This becomes severe in about 30% of pregnant women with NVP symptoms.1 One in 100-150 women will be admitted to hospital due to the severity of their condition. This extreme end of the nausea and vomiting spectrum is called hyperemesis gravidarum.2 Before the advent of intravenous rehydration the condition could be fatal. It can have a profound effect on the quality of women's lives and can cause feelings of depression, difficulties between the sufferer and their partner, friends and family, feelings of being a less effective parent, and concern for the health of the unborn child.3 Further complications for severe cases of HG which continue into the second trimester may include oesophageal tears, pre-eclampsia and placental dysfunction disorders.4

What causes NVP?

Medical research has shown an association between the pregnancy hormone human chorionic gonadotrophin (hCG) and pregnancy sickness, although this association only holds true when several women are grouped together in the investigation, rather than for each individual pregnant woman.5 In addition, high maternal blood levels of this hormone occur in twin pregnancies, and twin pregnancies are generally associated with increased pregnancy sickness.6

It is remarkable that the maternal hormone hCG, which is rising rapidly in weeks six to 107 has by electrophoresis, been shown to occur in at least five different isoforms or 'types'.8 In very early pregnancy (six to 10 weeks) the type with an 'acidic basis' is more prominent, whereas, by 11-15 weeks of pregnancy the more 'basic' type of hCG becomes the more prominent of the isoforms.8 It has been shown that the acidic type of hormone is the most active form of the hormone.9 This active acidic type of hCG has been shown to be present in higher quantities in women who have hyperemesis gravidarum than in normal pregnancies.10

Obviously, more investigation is needed into this under-funded and under-researched condition before we can be definite about the association of acidic hCG with pregnancy sickness.

However, it has been shown that there are grounds for believing pregnancy sickness is a physical hormone-based condition, rather than purely a somatic or 'mind over matter' reaction to a stressful condition.

When does NVP become HG?

If NVP becomes so severe and persistent that it prevents a woman from eating and drinking then it becomes HG. Clinical manifestations of HG include weight loss of 5% or more of pre-pregnancy weight, ketosis and/or a unine output of

Electrolyte imbalance can occur and if left untreated other complications can follow (see Table 1 overleaf for symptom comparison). Furthermore, when quality of life is significantly impacted and a woman is unable to work or care for herself and her family, then a diagnosis of HG would be appropriate. In some cases HG can last well into the second trimester or throughout the entire pregnancy.

How can the primary care nurse help?

Hyperemesis gravidarum is often under-recognised and trivialised by healthcare professionals as well as family and friends, so acting with compassion and understanding can make a welcome change to many women who may be feeling scared and shocked that they are so ill.11

Support is very important for women suffering with such an unrelenting condition, so referral to organisations such as the charity Pregnancy Sickness Support is appropriate. General advice can be offered, such as resting as much as possible and avoiding individual triggers such as smells and sounds which can lead to vomiting.

For mild to moderate NVP, symptoms tend to occur in two to four hour episodes, which tend to be similar from day to day. Keeping a symptom diary can therefore help women predict times between episodes when they will be able to eat and drink more readily.

Be careful if recommending 'morning sickness cures' to an HG sufferer; she will likely have been told innumerable times to try crackers and ginger. It may undermine confidence in healthcare professionals as well as adding to her feeling of isolation.

Safe and effective treatment for NVP is available, such as cyclizine or promethazine. Pyridoxine can also be added.12,13 Women should be reassured about their safety. Offer anti-emetics in primary care to women who find their NVP interferes with normal functioning.13

Women should be assessed for signs of dehydration and referred accordingly. Dip urine to look for ketones and assess weight loss. Suggested criteria for admission is outlined in Box 1.13

Women should be encouraged to keep a symptom diary and if possible a basic fluid balance chart.

Primary care nurses in Bath are able to provide an IV at home service for women with HG.14 This is an exciting development for primary care treatment of HG.

If a woman is largely bed-bound then assess for risk of DVT, and if appropriate, measure her for thromboembolic deterrent (TED) stockings.

Recurrence rates in subsequent pregnancies are high for HG, and it may be appropriate to have a care plan, including prophylactic treatment, in place prior to planned conception, particularly where a previous pregnancy has been terminated due to the severity of HG. Record a baseline weight for these women to aid later assessment.


NVP is a common and under-appreciated condition. Its most severe form HG results in termination of some pregnancies and many hospital admissions. Safe, effective therapy is available and should be prescribed where it is needed and wanted. Referral for support should always be offered.


Pregnancy Sickness Support


Information leaflets are obtainable on request.


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2. Goodwin TA. Hyperemesis Gravidarm. Clin Obstet Gynecol 1998p;41:597-605.

3. Mazzotta P, Magee L, Maltepe C, Lifshitz A, Navioz Y, Koren G. The perception of teratogenic risk by women with nausea and vomiting of pregnancy. Reproductive Toxicology 1999;13:313-9.

4. Bolin M, Akerud H, Cnattingius S, Stephansson O, Wikstrom AK. Hyperemesis Gravidarum and risks of placental dysfunction disorders: a population-based cohort study. BJOG 2013; [Epub ahead of print].

5. Masson GM, Anthony F, Chaul E. Serum Gonadotrophin and Schwangershaft's protein, Progesterone and Oestradiol levels in patients with nausea and vomiting in early pregnancy. BJOG 1985;92:211-5.

6. Kallen B. Hyperemesis during pregnancy and delivery outcome; A Registry Study. Eu J Obstet Gynecol Reprod Biol 1987;26:291-302.

7. Cole L. Biological Functions of HCG and HCG-related molecules. Reproductive Biology and Endocrinology 2010;8:102. Available at:

8. Wide L, Lee J-Y, Rasmussen C. A change in the isoforms of Human Gonadotrophin occurs around the 13th week of gestation. J Clin Endocrinol Metab 1994;78:1419-23.

9. Hoermann R, Kubota K, Amir SM. Role of subunit Sialic Acid in hepatic binding, plasma survival rate and in vitro thyrotrophic activity of human chorionic gonadotrophin. Thyroid 1993;3(1):41-7.

10. Jordan V, Grebe SKG, Cooke RR, Ford HC, Larsen PD, Stone PR, Salmond CE. Acidic isoforms of chorionic Gonadotrophin in European and Samoan women are associated with Hyperemesis Gravidarum and maybe thyrotrophic. J Clin Endocrinol 1999;50:619-27.

11. Munch S. A Qualitative Analysis of Physician Humanism: Women's Experiences with Hyperemesis Gravidarum. Journal of Perinatology 2000;20:540-7.

12. Arsenault MY, Lane CA.The management of Nausea and Vomiting of Pregnancy J Obstet Gynaecol Canada 2002;24:817-23.

13. Jarvis S, Nelson-Piercy C. Management of nausea and vomiting in pregnancy. BMJ 2011;342:1407-12.

14. Sirona Healthcare. Pioneering Service Helps Patients To Be Treated In Own Home [online] 2012. Available at: