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Hyperemesis gravidarum (HG)

Between 1% and 3% of pregnant women get extreme morning sickness. Here’s what you should know…

What is hyperemesis gravidarum?

It’s morning sickness at its worst.

"Described as unrelenting and excessive nausea and vomiting, it can make women sick up to 50 times a day (Sheffield Department of Gynaecology, 2011)."

Hyperemesis gravidarum means you are unable to take in food and fluid and can suffer fatigue, dehydration and weight loss (HER foundation, 2018). It can even cause the production of ketones, nutritional deficiencies, metabolic imbalances and difficulty doing your normal everyday tasks (Sheffield Department of Gynaecology, 2011). In short: not fun.

When will hyperemesis gravidarum happen?

Symptoms will most likely start in the first six weeks when you’ll probably just think you’re experiencing ‘normal’ morning sickness (NHS Choices, 2018). But with hyperemesis gravidarum, symptoms will become much more severe.

Symptoms will last until around 20 weeks or maybe even for the duration of pregnancy (NHS Choices, 2018). Get ready to be very, very sympathetic to friends who go through this.

Why does hyperemesis gravidarum occur?

It’s likely to be down to several factors related to the hormonal changes that happen during pregnancy.

During the first trimester of pregnancy, two things could play a part. They are serum HCG – a hormone produced during pregnancy, and the corpus luteum – a hormone-secreting structure that develops in an ovary when it releases an egg (Verberg et al, 2005).

Hyperemesis gravidarum has also been linked to a bacterial infection of the stomach (Verberg et al, 2005; Cardaropoli et al, 2014; Li et al, 2015). Women whose mums or sisters suffered from hyperemesis gravidarum are also more susceptible to it so there is a genetic factor at play too (McCarthy et al, 2014; Pregnancy Support Sickness (PSS) and the British Pregnancy Advisory Service (BPAS), 2015).

Who will get hyperemesis gravidarum?

Hyperemesis gravidarum affects an estimated 1% to 3% of pregnant women (RCOG, 2016a). Having had hyperemesis gravidarum during a previous pregnancy, being overweight, a first pregnancy and having a multiple pregnancy can increase your chances of getting HG. Women with trophoblastic disease – an extremely rare condition that involves abnormal growth of cells inside the uterus – can also be more likely to get HG (Sheffield Department of Gynaecology, 2011).

How can hyperemesis gravidarum betreated?

If you’re suffering, you’ll be glad to know some medications can help improve symptoms and can be used during pregnancy (RCOG, 2016b). They can even be used during the first 12 weeks (NHS Choices, 2018).

If you’re suffering, you’ll likely be given vitamin B6 as well as anti-histamines as a first port of call (RCOG, 2016b; NHS Choices, 2018). If that doesn’t do the trick, your doctor will move on to an anti-sickness (anti-emetic) drug called ondansetron. You’d receive this medication alongside a laxative as one of its side effects is extreme constipation (Pregnancy Support Sickness (PSS) and the British Pregnancy Advisory Service (BPAS), 2015). Following that, steroids can be another option (Pregnancy Support Sickness (PSS) and the British Pregnancy Advisory Service (BPAS), 2015).

Other medications out there can tackle hyperemesis gravidarum but many are not licensed in pregnancy. This is because pregnant women are usually excluded from drug trials or possible risks (Einarson, 2004; Anderka et al, 2012; Danielsson et al, 2014; Pasternak et al, 2014; Fejzo et al, 2016). But due to the seriousness of hyperemesis gravidarum, the benefits might outweigh the potential risks (Pregnancy Sickness Support, 2018).

If medication really isn’t working, women can be admitted to hospital. This allows women to take their fluids intravenously and receive anti-emetics via injections (RCOG, 2016b; NHS Choices, 2018).

Will hyperemesis gravidarum affect my baby?

Some evidence suggests particularly severe cases could mean women having their baby prematurely or a baby with a low birth weight (Gross et al, 1989; Dodds et al, 2006; Veenendaal et al, 2011). But the sooner you get medical help, the lower these risks are.

How can I get emotional help if I’m suffering from hyperemesis gravidarum?

Let’s not underestimate this: hyperemesis gravidarum can hugely affect your physical and emotional wellbeing (McCarthy et al, 2011; RCOG, 2016a). Heartbreakingly, an estimated 10% of women with the condition terminate wanted pregnancies as the symptoms are so extreme (HER, 2018; Pregnancy Sickness Support, 2018).

Hyperemesis gravidarum can prevent you from doing your job, from looking after other children, and might leave you feeling depressed and anxious. As well as speaking openly to friends and family about how you’re feeling, speak to your GP or midwife if you are struggling.

This page was last reviewed in May 2018.

Further information

Our support line offers practical and emotional support with feeding your baby and general enquiries for parents, members and volunteers: 0300 330 0700.

We also offer antenatal courses which are a great way to find out more about birth, labour and life with a new baby.

Make friends with other parents-to-be and new parents in your local area for support and friendship by seeing what NCT activities are happening nearby.

The HER Foundation has lots of useful information and support on HG

Pregnancy Sickness Support is a UK charity working to improve care, treatment and support for women suffering from Nausea and Vomiting in Pregnancy (NVP) and Hyperemesis Gravidarum (HG)

NHS choices provides information on hyperemesis gravidarum

Anderka M, Mitchell AA, Louik C, Werler MM, Hernández‐Diaz S, Rasmussen SA. (2012). Medications used to treat nausea and vomiting of pregnancy and the risk of selected birth defects. Birth Defects Research Part A: Clinical and Molecular Teratology. 94(1):22-30. Available from: [Accessed 27th March 2018]

Cardaropoli S, Rolfo A,  Todros T. (2014). Helicobacter pylori and pregnancy-related disorders. World Journal of Gastroenterology: WJG. 20(3):654. Available from: [Accessed 27th March 2018]

Dodds L, Fell DB, Joseph KS, Allen VM, Butler B. (2006) Outcomes of pregnancies complicated by hyperemesis gravidarum. Obstetrics & Gynecology, 107(2):285-292. Available from: [Accessed 27th March 2018]

Fejzo MS, MacGibbon KW, Mullin PM. (2016) Ondansetron in pregnancy and risk of adverse fetal outcomes in the United States. Reproductive Toxicology. (62):87-91. Available from: [Accessed 27th March 2018]

Gross S, Librach C, Cecutti A. (1989) Maternal weight loss associated with hyperemesis gravidarum: a predictor of fetal outcome. American Journal of Obstetrics & Gynecology. 160(4):906-909. Available from: [Accessed 27th March 2018]

HER foundation (2018). About hyperemis gravidarum. Available from: [Accessed 27th March 2018]

Li, L, Li L, Zhou X, Xiao S, Gu H, Zhang G. (2015). Helicobacter pylori infection is associated with an increased risk of hyperemesis gravidarum: a meta-analysis. Gastroenterology research and practice. Available from: [Accessed 27th March 2018]

McCarthy, FP, Khashan AS, North RA, Moss-Morris R, Baker PN, Dekker G; SCOPE consortium. (2011) A prospective cohort study investigating associations between hyperemesis gravidarum and cognitive, behavioural and emotional well-being in pregnancy. PloS one. 6(11):e27678.

Available from: [Accessed 27th March 2018]

McCarthy FP, Lutomski JE, Greene RA (2014). Hyperemesis gravidarum: current perspectives. International journal of women's health. 6:719-725. Available from: [Accessed 27th March 2018]

NHS Choices (2018). Severe vomiting in pregnancy. Available from: [Accessed 27th March 2018]

Pasternak B, Svanström H, Hviid A. (2013) Ondansetron in pregnancy and risk of adverse fetal outcomes. New England Journal of Medicine. 368(9):814-823. Available from: [Accessed 27th March 2018]

Pregnancy Support Sickness (PSS) and the British Pregnancy Advisory Service (BPAS). (2015) I could not survive another day. Available from: [Accessed 27th March 2018]

RCOG. (2016a) Pregnancy sickness (nausea and vomiting of pregnancy and hyperemesis gravidarum. Available from: [Accessed 27th March 2018]

RCOG. (2016b) The management of nausea and vomiting of pregnancy and hyperemesis gravidarum. Available from: [Accessed 27th March 2018]

Sheffield Department of Gynaecology. (2011) Hyperemis Gravidarum: nausea and vomiting in pregnancy. Available from:[1].pdf [Accessed 27th March 2018]

Veenendaal MV, Van Abeelen AF, Painter RC, Van der Post JA, Roseboom TJ. (2011) Consequences of hyperemesis gravidarum for offspring: a systematic review and meta‐analysis. BJOG: An International Journal of Obstetrics & Gynaecology. 118(11):1302-1313. Available from: [Accessed 27th March 2018]

Verberg MFG, Gillott DJ, Al-Fardan N, Grudzinskas JG. (2005) Hyperemesis gravidarum, a literature review. Human reproduction update. (11):527-539. Available from: [Accessed 27th March 2018]

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