Morning Sickness or Hyperemesis Gravidarum? Understanding Pregnancy Sickness and When to Ask for Help

Dr Kenga Sivarajah

2 days ago

10 min read

Updated: 24 hours ago

Feeling sick during pregnancy is very common, particularly in the first few months. For some women, nausea is an occasional inconvenience. For others, it can become an exhausting, all-day experience that affects their ability to eat, work, sleep or enjoy everyday life.

Although it is often called morning sickness, pregnancy nausea can happen at any time of the day or night. And while it usually improves as pregnancy progresses, some women experience much more severe symptoms.

This is known as hyperemesis gravidarum (HG).

At Central Health London, we believe that pregnancy sickness deserves to be taken seriously, whatever its severity. You do not need to be losing weight, becoming dehydrated or struggling to cope before asking for help.

There are safe and effective treatments available, and getting the right support early can make a real difference to how you feel.

What Is the Difference Between Morning Sickness and Hyperemesis Gravidarum?

Pregnancy sickness usually begins between four and seven weeks of pregnancy. Most women find their symptoms improve by around 12 to 20 weeks, although some experience nausea for longer.

Hyperemesis gravidarum is a more severe form of pregnancy sickness, affecting approximately one to three in every 100 pregnancies.

The distinction is not simply how often you vomit. Some women experience almost constant nausea without frequent vomiting, yet find it equally debilitating.

What matters is how severely the symptoms affect your wellbeing, your ability to eat and drink, and your everyday life.

Morning Sickness vs Hyperemesis Gravidarum

Feature	Typical Morning Sickness	Hyperemesis Gravidarum
Nausea	Often comes and goes	May be severe and almost constant
Vomiting	Occasional or frequent	Often persistent and difficult to control
Eating & drinking	Usually possible, although some foods may be difficult	May become extremely difficult
Hydration	Usually maintained	Dehydration may develop
Weight	Usually relatively stable	Weight loss may occur
Daily life	May be uncomfortable and tiring	Can significantly disrupt work, family life and everyday activities
Treatment	Simple measures or medication may help	Often requires medication and sometimes intravenous fluids or hospital care

These are general differences rather than strict diagnostic criteria. You do not need to experience every symptom or lose weight before seeking medical advice.

Why Does Hyperemesis Gravidarum Happen? What New Research Has Shown

For many years, the causes of severe pregnancy sickness were poorly understood. Some women were even led to believe that their symptoms were related to anxiety or their ability to cope with pregnancy.

We now have much better scientific evidence explaining why some women experience such severe illness.

Important research published in Nature in 2023 identified a hormone called GDF15 as a major contributor to nausea and vomiting during pregnancy.

GDF15 is produced in large quantities by the developing pregnancy and placenta. It acts on a specialised part of the brain involved in regulating nausea, vomiting and appetite.

Researchers discovered that the severity of pregnancy sickness depends partly on how sensitive a woman’s body is to this hormone.

This helps explain why one woman may experience relatively mild symptoms while another becomes extremely unwell.

The discovery confirms something important: hyperemesis gravidarum is a genuine biological illness. It is not caused by a woman’s attitude towards pregnancy or her ability to manage stress.

Although research into treatments targeting GDF15 is still developing, understanding the biological causes of HG is an important step towards better prevention and treatment in the future.

Signs of Hyperemesis Gravidarum: When Pregnancy Sickness Becomes More Severe

Every woman’s experience of pregnancy sickness is different.

Some women find their nausea gradually becomes more intense. Others develop severe symptoms surprisingly quickly.

Signs of hyperemesis gravidarum may include:

Persistent nausea that makes eating, drinking or daily activities difficult.
Frequent vomiting or being unable to keep fluids down.
Feeling dizzy, faint or unusually weak.
Passing much less urine than usual or noticing that it has become very dark.
Losing weight unintentionally.
Extreme tiredness and difficulty managing normal activities.
Finding it increasingly difficult to work, sleep or care for yourself or your family.

Some women experience particularly distressing nausea without vomiting frequently.

If your symptoms are making everyday life difficult, please speak to your doctor or midwife. Early treatment may help prevent symptoms from becoming more severe.

Can You Have Hyperemesis Without Losing Weight?

Yes. Although weight loss is common in hyperemesis gravidarum, it is not essential for diagnosis.

Severe nausea and vomiting may affect your ability to eat and drink well before there is a noticeable change in your weight.

Doctors assess the whole picture, including how you are feeling, your fluid intake, any weight changes, and the impact on your daily activities.

Current guidance also advises that urine ketones should not be used to judge the severity of hyperemesis or dehydration.

You do not need to wait until you have lost a particular amount of weight before seeking medical advice.

Can Hyperemesis Gravidarum Affect You or Your Baby?

It is understandable to worry about your baby’s wellbeing when you are feeling so unwell yourself.

The good news is that many women who experience hyperemesis gravidarum go on to have healthy pregnancies and babies.

Our priority is to help you feel better, maintain your hydration and nutrition, and make sure your pregnancy continues to be monitored appropriately.

When vomiting is severe or prolonged, it can sometimes lead to dehydration, changes in the body’s mineral and salt balance, or nutritional deficiencies.

In a small number of women, these problems can become serious without appropriate treatment.

Severe or prolonged hyperemesis, particularly when accompanied by substantial weight loss, has also been associated with an increased risk of babies being born smaller than expected.

These risks are one reason we encourage women to seek advice early rather than attempting to manage increasingly difficult symptoms alone.

Your doctor can explain any concerns in the context of your own pregnancy and recommend the monitoring or treatment that is right for you.

The Emotional Impact of Hyperemesis Gravidarum

Severe pregnancy sickness affects much more than your stomach.

Constant nausea, disturbed sleep, exhaustion and the inability to eat normally can make even simple everyday activities feel overwhelming.

For some women, hyperemesis means being unable to work, care for other children, socialise or enjoy a pregnancy they may have been looking forward to for a long time.

It can also feel isolating, particularly when friends or family have experienced only mild pregnancy sickness and may not appreciate quite how unwell you feel.

Research has increasingly recognised the significant emotional and psychological impact of hyperemesis, including its association with anxiety, depression and, for some women, distressing memories of pregnancy.

At Central Health London, we believe that caring for women with hyperemesis means looking after both their physical and emotional wellbeing.

Our multidisciplinary team can bring together obstetric, medical, psychological and psychiatric expertise where helpful.

This is not because hyperemesis is a psychological condition. It is because prolonged physical illness can have a profound emotional impact, and good medical care should recognise both.

Women should feel comfortable talking openly about how they are coping, including any worries about their pregnancy or difficult decisions they may be facing.

What Treatments Are Available for Hyperemesis Gravidarum?

There are several effective ways of treating pregnancy sickness, and the right approach depends on your symptoms and individual circumstances.

We aim to make treatment as straightforward and comfortable as possible, recognising that women who are already feeling very unwell may find repeated appointments and hospital visits particularly difficult.

1. Anti-Sickness Medication

Several anti-sickness medicines, also called antiemetics, can be prescribed during pregnancy, including in the first trimester.

Your doctor will recommend a treatment based on your symptoms, medical history and the available evidence about safety in pregnancy.

Sometimes one medicine is sufficient. Other women benefit from a combination of treatments.

If you find it difficult to keep tablets down, there may be alternative ways of taking medication.

You do not need to wait until your symptoms become severe before discussing treatment.

2. Intravenous Fluids and Rehydration

If you are struggling to drink enough, intravenous fluids can help restore hydration and make you feel considerably better.

This treatment involves giving fluids directly into a vein through a small drip.

Depending on your symptoms, you may also need blood tests, medication to control vomiting, or vitamin supplementation.

Some women can receive dedicated ambulatory rehydration and anti-sickness therapy in a quiet clinic setting and return home the same day.

Others may need hospital admission, particularly if dehydration or nutritional difficulties are more significant.

Your doctor will help identify the safest and most appropriate option.

3. Nutritional Support and Follow-Up

When nausea continues for several weeks, eating enough can become a challenge.

Our approach is to help you maintain adequate nutrition without placing additional pressure on you to eat foods that you simply cannot tolerate.

For women with prolonged or severe symptoms, nutritional assessment, vitamin supplementation and regular review may be helpful.

Thiamine, a B vitamin, is particularly important for women with prolonged vomiting or severely reduced food intake.

Your treatment can be adjusted as symptoms improve or change throughout pregnancy.

Can You Manage Pregnancy Sickness at Home?

For women with milder symptoms who can maintain their fluid intake, a few practical changes may make everyday life a little easier.

You might find it helpful to:

Eat little and often. Small meals and snacks are sometimes easier to tolerate.
Choose foods you enjoy or can manage. There is no need to force yourself to eat foods that make you feel worse.
Take small, frequent sips of fluid. Cold drinks or ice lollies may be easier for some women.
Avoid smells or foods that trigger nausea. These vary considerably between individuals.
Rest when you need to. Tiredness can make nausea more difficult to manage.
Accept practical help. Support with cooking, childcare or household tasks can make a substantial difference.

Some women also find ginger or acupressure helpful, although neither works for everyone.

If these measures are not helping, or your nausea is affecting your ability to manage daily life, there is no reason to continue struggling without medical advice.

When Should You Seek Medical Help for Pregnancy Sickness?

It can sometimes be difficult to know when pregnancy sickness has become severe enough to need medical attention.

As a general guide, we would encourage you to contact your doctor or maternity team if you are finding it difficult to eat or drink, are vomiting repeatedly, or feel your symptoms are becoming harder to manage.

Please seek urgent assessment if:

You cannot keep fluids down.
You are passing very little urine.
You feel faint, unusually weak or significantly dehydrated.
You are losing weight rapidly.
You cannot take important prescribed medication.
Your symptoms are worsening despite treatment.

If you become acutely unwell, collapse, develop confusion or severe abdominal pain, or have blood in your vomit, seek emergency medical attention.

These symptoms may need immediate investigation and treatment rather than a routine outpatient appointment.

If you are unsure what level of care you need, your maternity team, GP, NHS 111 or local maternity assessment service can help guide you.

Will Hyperemesis Gravidarum Improve as Pregnancy Progresses?

Many women notice that pregnancy sickness begins to improve towards the end of the first trimester or during the second trimester.

However, hyperemesis gravidarum can last longer, and for a smaller number of women symptoms continue throughout pregnancy.

If you are still feeling unwell at 16 or 20 weeks, it does not mean that treatment cannot help.

Your doctor can continue to review your symptoms and adjust treatment to make the remainder of your pregnancy as comfortable as possible.

For women who have experienced HG in a previous pregnancy, planning ahead can also be helpful, as symptoms may recur in subsequent pregnancies.

How Central Health London Can Help

At Central Health London, we understand that pregnancy sickness can range from a relatively minor inconvenience to an illness that profoundly affects your daily life.

Our approach is personal, practical and compassionate.

We want to understand not only how often you are vomiting, but also how you are sleeping, eating, feeling emotionally and managing everyday life.

Our consultant obstetricians can assess your symptoms, discuss appropriate medication, arrange investigations and help coordinate any additional treatment or hospital care you may need.

Because our practice brings together obstetricians, GPs, psychiatrists, psychologists and other specialists, we can also provide more joined-up support when pregnancy sickness affects your wider physical or emotional wellbeing.

Most importantly, we believe you should feel listened to, reassured and involved in decisions about your care.

If pregnancy sickness is making your life difficult, please get in touch. You do not need to wait until it becomes unbearable before asking for help.

If you are concerned about hyperemesis gravidarum (HG), our outpatient clinic provides rapid medical support, including specialist hyperemesis gravidarum treatment and in-clinic IV fluid infusions to promptly relieve severe nausea and dehydration.

Managing severe sickness can feel overwhelming, but you do not have to struggle alone. If your symptoms persist or you need immediate relief, contact our London clinic or book a consultation with our specialist team today.

Morning Sickness vs Hyperemesis Gravidarum FAQs

How do I know if I have morning sickness or hyperemesis gravidarum?

The main difference is how severely your symptoms affect your ability to eat, drink and manage daily life. Persistent nausea, frequent vomiting, dehydration or weight loss may suggest hyperemesis gravidarum. Your doctor can assess your symptoms and recommend appropriate treatment.

Can I have hyperemesis gravidarum without vomiting frequently?

Yes. Some women experience severe, almost constant nausea that makes eating, drinking and everyday activities extremely difficult, even without frequent vomiting.

Is hyperemesis gravidarum dangerous for my baby?

Most women with HG go on to have healthy babies. Severe or prolonged illness, especially when accompanied by substantial weight loss, may increase the risk of some complications. Early treatment and appropriate monitoring are important for both your wellbeing and your baby’s development.

Is it safe to take anti-sickness medication in early pregnancy?

Several anti-sickness medicines can be used during early pregnancy. Your doctor can explain the available options and help you choose a treatment based on your symptoms, medical history and individual circumstances.

When should I go to hospital for pregnancy sickness?

Seek urgent medical assessment if you cannot keep fluids down, are passing very little urine, feel faint or are becoming increasingly weak. Your healthcare team can advise whether treatment can be provided without admission or whether hospital care would be safer.

Does hyperemesis gravidarum mean I will feel sick throughout my pregnancy?

Not necessarily. Many women improve during the second trimester, although some experience symptoms for longer. Treatment can continue to help even when symptoms are prolonged.

What causes hyperemesis gravidarum?

Recent research has identified the hormone GDF15, produced largely by the developing pregnancy and placenta, as an important biological contributor. Differences in how sensitive women are to this hormone help explain why some experience much more severe sickness than others.

Can hyperemesis gravidarum affect my mental health?

Yes. Prolonged nausea, vomiting, exhaustion and disruption to daily life can have a substantial emotional impact. Some women experience anxiety, low mood or distress related to their illness. Psychological support can be helpful alongside medical treatment.

Medical Information and Further Reading

This article provides general information and is not a substitute for individual medical advice.