Understanding the Spectrum of NVP and HG 

When a woman presents with nausea and vomiting in pregnancy (NVP) and you have excluded other differential aetiology, the first question you need to ask yourself is: what is the severity of her symptoms and could this be hyperemesis gravidarum (HG). Nausea and vomiting in pregnancy occurs across a spectrum with hyperemesis gravidarum being the severest form and representing a complication of pregnancy. 
NVP affects 90% of pregnancies¹ and is defined as the symptom of nausea and/or vomiting during pregnancy when onset is prior to 16 weeks of gestation and where there are no other causes. Symptoms typically start between week 4 and 7 and can be graded as mild, moderate or severe. 
HG affects 0.3 – 1.0% of pregnancies² and should be diagnosed when the nausea and/or vomiting is severe, begins before 16 weeks gestation, there is an inability to eat and drink normally and daily living activities are significantly limited. Signs of dehydration are considered contributory to diagnosis. This definition represents a shift from a historic reliance on objective measures such as weight loss and electrolyte imbalance, and towards subjective patient focused criteria with the aim of achieving an improved recognition and diagnosis of HG. 
If the onset of nausea and vomiting is in the 3rd trimester / postpartum period then more serious conditions such as pre-eclampsia, HELLP or acute fatty liver of pregnancy need to be considered. 
The theoretical basis for NVP and HG has changed significantly. Fetal production of GDF15 and maternal sensitivity to it both contribute substantially to risk of developing NVP and HG, specifically hypersensitivity to the vomiting hormone Growth Differentiation Factor 15 (GDF-15).³ 

Diagnosis and Monitoring 

The Pregnancy-Unique Quantification of Emesis [PUQE] score can be used to determine whether the NVP is mild, moderate or severe.⁴ 

Question	Not at all (1)	1 hour or less (2)	2-3 hours (3)	4-6 hours (4)	More than 6 hours (5)
In the last 24 hours, for how long have your felt nauseated or sick to your stomach?	1	2	3	4	5
In the last 24 hours have you vomited or thrown up?	I did not throw up (1)	1-2 times (2)	3-4 times (3)	5-6 times (4)	7 or more times (5)
In the last 24 hours how many times have you had retching or dry heaves without bringing anything up?	No time (1)	1-2 times (2)	3-4 times (3)	5-6 times (4)	7 or more times (5)

PUQE-24 score: Mild ≤ 6, Moderate = 7-12, Severe = 13-15. 

The PUQE score can also be used to assess the response to treatment for mild to moderate NVP but is not valid for severe NVP and HG.⁵ 

Clinicians need to move away from checking urine ketones as a means of diagnosing and monitoring the treatment success of NVP/HG. Ketones reflect the catabolism of adipose tissue stores secondary to prolonged starvation rather than dehydration. A systematic review and meta-analysis found no correlation between the grade of ketonuria and the severity of HG.⁶ Only a minority of patients with HG will actually have ketones. The diagnosis of dehydration should be based on history and examination not a urine dipstick test. A urine dipstick test should only be used if a UTI, DKA or pre-eclampsia is suspected. 

Management in Primary Care and Criteria for Referral 

Next, you need to think about whether this patient can be managed in Primary Care or whether she requires hospital assessment/admission. 

Women with mild to moderate NVP (PUQE score 3-12) who are able to tolerate anti-emetics and maintain hydration should be managed in primary care. Often these women do not require anti-emetics in which case lifestyle measures should be encouraged: 

• Rest: A survey of 114 women found that rest was noted by most respondents to be the only effective management strategy apart from antiemetic medications.⁷A structured daily diary can be useful in identifying periods of reduced nausea so eating and drinking can be planned for these times. 
• Ginger: this is a therapeutic option for women with mild-to-moderate NVP, which is commonly improved by dietary changes however, HG requires pharmacological treatment. A self-selected internet-based survey of 512 women hospitalised with HG within a one-year period and collectively experiencing 965 HG pregnancies, concluded that ginger was unhelpful in controlling HG symptoms. It also caused unpleasant side-effects, worsening of mood, breakdown of the doctor–patient relationship and a delay in receiving effective management with worsening and longer duration of symptoms.⁸ 
• Acupressure and electrical stimulation: a systematic review comprising 14 studies and meta-analysis showed that acupressure and electrical stimulation at the pericardium 6 point may have some benefit in alleviating nausea but less so vomiting.⁹ 

For severe NVP and HG, anti-emetics are usually required. Anti-emetics may not cure the symptoms but can palliate them until natural improvement occurs. 

Indications for Secondary Care Assessment/Admission 

Assessment/admission to secondary care should be considered when there is: ¹⁵ 

• continued nausea and/or vomiting and an inability to keep down oral antiemetics, 
• clinical dehydration and unsuccessful ambulatory care, OR 
• continued nausea and/or vomiting associated with weight loss (>5% body weight), despite oral antiemetics, OR 
• confirmed or suspected comorbidity such as urinary tract infection with inability to tolerate oral antibiotics, OR 
• comorbidity (epilepsy, diabetes mellitus, HIV, psychiatric disorders, hypoadrenalism) and unable to tolerate oral intake and medication hence could present with further complications. 

Cessation of Anti-emetics and Psychological Support 

Women often ask how and when they should stop their anti-emetics. 90% of mild to moderate NVP cases resolve by 20 weeks¹⁰; the majority of HG patients continue to have symptoms after 16 weeks¹¹. If a woman feels her symptoms have been controlled for a reasonable period of time (e.g. 2-3 weeks) and she is now able to function at a pre-pregnancy level, a gradual reduction in anti-emetics can be trialled. 

Alongside the medical management, psychological assessment and support should be central to the management plan. Around 10% of women with HG will terminate a wanted pregnancy.¹¹ Pregnancy Sickness Support found that most of these women had not been offered the full range of treatments available with less than 10% being offered steroids.¹³ Evidence shows that consequences may persist beyond pregnancy, with reports of post-traumatic stress symptoms in up to 20% of women with HG¹⁴. Women can be signposted to Pregnancy Sickness Support to acquire helpline, volunteer, forum and educational online support. Referral to perinatal mental health services should be considered. 

No anti emetics are currently licensed in HG, refer to RCOG guidelines for recommended treatment options¹⁶ 

1. 1. 1. Gadsby R, Rawson V, Dziadulewicz E, Rousseau B, Collings H. Nausea and vomiting of pregnancy and resource implications: the NVP Impact Study. Br J Gen Pract. 2019 Mar;69(680):e217-e23. doi: 10.3399/bjgp18X700745. 
      2. Niebyl JR. Clinical practice. Nausea and vomiting in pregnancy. N Engl J Med. 2010 Oct 14;363(16):1544-50. 
      3. University of Cambridge. Why seven in ten women experience pregnancy sickness [Internet]. Cambridge: University of Cambridge; 2023 Dec 13 [cited 2025 Oct]. Available from: https://www.cam.ac.uk/stories/pregnancy-sickness-cause (Accessed November 2025) 
      4. Koren G, Boskovic R, Hard M, Maltepe C, Navioz Y, Einarson A. Motherisk-PUQE (pregnancy-unique quantification of emesis and nausea) scoring system for nausea and vomiting of pregnancy. Am J Obstet Gynecol. 2002 May;186(5 Suppl Understanding):S228-31. 
      5. Royal College of Obstetricians and Gynaecologists. (2024). The management of nausea and vomiting of pregnancy and hyperemesis gravidarum (Green-top Guideline No. 69). RCOG. https://www.rcog.org.uk/media/y3fen1x1/gtg69-hyperemesis.pdf (Accessed December 2025) 
      6. Niemeijer MN, Grooten IJ, Vos N, Timshel S, Wade O, Painter I, et al. Diagnostic markers for hyperemesis gravidarum: a systematic review and metaanalysis. Am J Obstet Gynecol. 2012;211:150.e1-e15. 
      7. O’Hara M. Women’s experience of hyperemesis gravidarum: Results of self-reported online surveys [Internet]. Pregnancy Sickness Support; 2013 [cited 2025 Oct]. Available from: www.pregnancysicknesssupport.org.uk/documents/HCPconferenceslides/womens-experience-2013-MOH.pdf. 
      8. NHS Bristol, North Somerset and South Gloucestershire Integrated Care Board. (2022). Hyperemesis gravidarum. Remedy. https://remedy.bnssg.icb.nhs.uk/adults/gynaecology/hyperemesis-gravidarum/? (Accessed December 2025) 
      9. Helmreich RJ, Shiao SY, Dune LS. Meta-analysis of acustimulation effects on nausea and vomiting in pregnant women. Explore (NY). 2006 Sep-Oct;2(5):412-21. doi: 10.1016/j.explore.2006.06.002. Erratum in: Explore (NY). 2007 Mar-Apr;3(2):94. PMID: 16979105. 
      10. Royal College of Obstetricians and Gynaecologists. (2016). The management of nausea and vomiting of pregnancy and hyperemesis gravidarum (Green-top Guideline No. 69). https://www.rcog.org.uk/media/y3fen1x1/gtg69-hyperemesis.pdf (Accessed November 2025) 
      11. Lacroix, R., Eason, E., & Melzack, R. (2000). Nausea and vomiting during pregnancy: A prospective study of its frequency, intensity, and patterns of change. American Journal of Obstetrics and Gynecology, 182(4), 931–937. https://pubmed.ncbi.nlm.nih.gov/10764476/       
      12. Pregnancy Sickness Support, BPAS. I could not survive another day. Improving treatment and tackling stigma: lessons from women’s experience of abortion for severe pregnancy sickness [Internet]. PSS; [cited 2025 Oct]. Available from: https://www.pregnancysicknesssupport.org.uk/documents/HGbpasPSS_report_docx.pdf. (Accessed November 2025) 
      13. Dean, C., & Murphy, C. (2015). I could not survive another day: Improving treatment and tackling stigma — lessons from women’s experiences of abortion for severe pregnancy sickness. BPAS / Pregnancy Sickness Support. https://www.bpas.org/media/qqnjgnmq/hgbpaspssreport_docx.pdf (Accessed Decmber 2025) 
      14. Christodoulou-Smith J, Gold JI, Romero R, Heitmann H, Zaki A, Korst L. Posttraumatic stress symptoms following pregnancy complicated by hyperemesis gravidarum. J Matern Fetal Neonatal Med. 2011 Nov;24(11):1307-11. doi: 10.3109/14767058.2011.582904. 
      15. Royal College of Obstetricians and Gynaecologists. (2024). The management of nausea and vomiting of pregnancy and hyperemesis gravidarum (Green-top Guideline No. 69). RCOG. https://www.rcog.org.uk/media/y3fen1x1/gtg69-hyperemesis.pdf (Accessed December 2025)
      16. Royal College of Obstetricians and Gynaecologists. (2024). The management of nausea and vomiting of pregnancy and hyperemesis gravidarum (Green-top Guideline No. 69). RCOG. https://www.rcog.org.uk/media/y3fen1x1/gtg69-hyperemesis.pdf (Accessed December 2025) EXE-E/IPR-XON-2465-v1     Oct 2025 

All Posts