Hyperemesis Gravidarum: Complete UK Guide

What Is Hyperemesis Gravidarum?

Hyperemesis gravidarum, usually shortened to HG, is a severe form of pregnancy sickness. Unlike ordinary morning sickness, it is persistent, relentless, and can lead to weight loss, dehydration, and nutritional deficiency. It affects around 1 to 3 in every 100 pregnancies in the UK.

HG is recognised as a medical condition rather than an exaggerated version of normal nausea. It often needs treatment, and in many cases support from hospital. It is not something you can push through alone with willpower and crackers.

How HG Differs From Normal Morning Sickness

The key difference is severity and impact. Typical morning sickness is unpleasant but you can usually still eat, drink, and function. With HG, the vomiting is so frequent and intense that you cannot keep down food or fluids, and daily life becomes impossible.

Signs that point to HG rather than normal sickness include:

Being sick more than three to four times a day
Inability to keep any food or fluids down
Losing 5 per cent or more of your pre-pregnancy weight
Dark, strong-smelling urine and passing very little
Dry mouth, dizziness, and confusion
Inability to work, care for yourself, or look after other children

When HG Usually Starts and Ends

HG typically begins between weeks 6 and 8 of pregnancy, often more suddenly than ordinary morning sickness. It usually peaks around weeks 9 to 13. For most women it eases by weeks 16 to 20, but a significant minority continue to have symptoms into the second and even third trimester.

Some women are unwell for the entire pregnancy. This is less common but it does happen, and it requires ongoing medical support.

What Causes HG

The exact cause is not fully understood, but contributing factors include:

Very high levels of hCG, especially in twin or multiple pregnancies
Increased sensitivity to oestrogen and progesterone
Genetics - having a mother or sister who had HG raises your risk
Previous HG in an earlier pregnancy
A history of motion sickness or migraines
Carrying a female baby (a weak statistical link)

HG is not caused by anything you did or did not do.

How HG Is Treated in the UK

Treatment is stepped, based on how unwell you are:

Anti-sickness medication (antiemetics) prescribed by your GP, such as cyclizine, promethazine, or ondansetron
Vitamin B6 to help reduce nausea
Oral rehydration salts if you are dehydrated but can still drink a little
Thiamine supplements if vomiting has been prolonged, to protect against rare complications
Hospital admission for intravenous fluids and monitored medication if you cannot keep anything down
In severe cases, a short stay on an antenatal ward for stabilisation

Safe and effective medications exist, and the NHS takes HG seriously.

Emotional and Practical Impact

HG can be emotionally draining. Many women describe feeling isolated, frightened, and depressed, especially if they are unwell for weeks or months. The impact on work, relationships, and caring for other children can be significant.

Practical steps that help include:

Telling your partner, family, and close friends exactly how bad it is
Accepting offers of help with cooking, shopping, and childcare
Speaking to your employer about sick leave or reasonable adjustments
Asking your midwife to refer you to a perinatal mental health team if you are struggling emotionally
Connecting with HG support charities such as the Pregnancy Sickness Support charity

A Reassuring Note

HG is horrible to live through, but with proper treatment most women go on to have healthy pregnancies and healthy babies. The most important step is to ask for help early - do not wait until you are dangerously dehydrated. Your GP, midwife, and local hospital have seen HG many times and know how to support you through it.