Understanding nausea and vomiting in pregnancy

What is Nausea and Vomiting in Pregnancy ?

Nausea and vomiting of pregnancy  is a common condition that affects up to 70–80% of pregnant women. It usually begins around the 4th to 7th week of pregnancy and tends to improve by weeks 12–14. However, in some women, it can continue beyond the first trimester.
Mild to moderate symptoms are part of a healthy pregnancy, but in more severe cases, a condition called Hyperemesis Gravidarum (HG) may develop. This is a serious form of pregnancy sickness requiring medical intervention.

Symptoms

Women may experience:

• Nausea with or without vomiting
• Sensitivity to smells
• Fatigue
• Loss of appetite
• Increased salivation
• Dehydration (in more severe cases)
• Dizziness or lightheadedness

Hyperemesis Gravidarum symptoms include:

• Persistent and severe vomiting
• Inability to keep food or fluids down
• Weight loss (more than 5% of pre-pregnancy weight)
• Signs of dehydration (dry mouth, reduced urination, dark urine)
• Electrolyte imbalance

Why Does It Happen?

While the exact cause of this  is not fully understood, several factors are thought to contribute:

1. Hormonal Changes – The rise in pregnancy hormones, particularly human chorionic gonadotropin (hCG) and oestrogen, is strongly linked to nausea and vomiting. Women with twins or a molar pregnancy, who have higher hCG levels, often have more severe symptoms.
2. Genetic Predisposition – Hyperemesis can run in families. If your mother or sister had it, you're more likely to experience it too.
3. Gastrointestinal Sensitivity – The slowing down of the digestive system in pregnancy due to progesterone can contribute to nausea.
4. Psychological and Emotional Factors – Fatigue, stress, and anxiety may worsen symptoms but are not considered primary causes.
5. Other Possible Contributors – Infections like Helicobacter pylori, nutrient deficiencies (e.g., Vitamin B6), and thyroid function abnormalities may also play a role.

General Advice and Lifestyle Management

In most cases, symptoms can be eased with a few changes to your diet and daily routine. 

• Eat small, frequent meals throughout the day. Avoid long gaps without food.
• Choose bland, dry, and high-carbohydrate snacks, like crackers, toast, or rice.
• Avoid strong smells and foods that trigger your nausea.
• Sip fluids slowly and regularly – cold, fizzy drinks or diluted fruit juice may be more tolerable.
• Try eating a plain snack before getting out of bed in the morning.
• Avoid lying down soon after eating.
• Rest as much as possible – tiredness can worsen symptoms.

Some women find relief with:

• Ginger (tea, capsules, or biscuits)
• Acupressure wristbands (e.g., Sea-Bands)

These remedies are considered safe but results may vary from person to person.

When to Seek Medical Help

Contact your obstetrician or GP if you:

• Are unable to keep any fluids or food down for 24 hours
• Experience weight loss
• Feel dizzy, faint, or notice very dark urine
• Have signs of dehydration
• Feeling severe nausea that is effecting your physical & mental health

Prompt medical review can prevent complications for both mother and baby

Medical Treatment Options

If lifestyle measures are not enough, medical treatments are safe and effective. 

We try to manage it in a  stepwise approach:

1. Xonvea – This is the only licensed medication in the UK specifically for nausea and vomiting in pregnancy. It is a combination of doxylamine (an antihistamine) and pyridoxine (vitamin B6). Xonvea is taken as a modified-release tablet and is usually started with two tablets at bedtime. Dosing can be gradually adjusted depending on symptom control, up to a maximum of four tablets per day.
2. Antihistamines – Such as cyclizine or promethazine. These help reduce nausea and are commonly used.
3. Antiemetics – Like metoclopramide or ondansetron may be prescribed in more moderate or severe cases. These require a prescription and a clinical discussion of benefits versus risks.
4. Intravenous (IV) Fluids – For women with dehydration or severe vomiting, fluids may be given in a hospital setting.
5. Steroids – In very rare and resistant cases, corticosteroids may be used under specialist guidance.

All medication decisions are based on severity, safety profile, and individual tolerance

Hyperemesis Gravidarum – More Than Just ‘Morning Sickness’

HG affects around 1–3% of pregnancies and can significantly impact physical and mental health. Hospitalisation may be necessary, and a multi-disciplinary approach involving obstetricians, Obstetrics physicians, dietitians, and sometimes mental health professionals can be required.

Signs of HG include:

• Prolonged and severe nausea and vomiting
• Inability to tolerate any food or fluids for over 24 hours
• Weight loss greater than 5% of pre-pregnancy weight
• Clinical signs of dehydration (dry mucous membranes, hypotension, tachycardia)
• Electrolyte imbalances (e.g., low potassium or sodium)
• Recurrent hospital admissions for rehydration or antiemetic treatment
• Functional impairment due to the severity of symptoms

My Role as Your Private Obstetrician

As your Consultant Obstetrician, I offer tailored care based on your symptoms, history, and preferences. My role includes:

• Early diagnosis and severity assessment
• Personalised care plans for nutrition and hydration
• Safe and appropriate prescribing of medications based on up-to-date evidence
• Monitoring for complications such as dehydration or weight loss
• Referral to hospital if needed for IV treatment or further investigation
• Reassurance and emotional support, as prolonged sickness can be distressing
• Collaborating with midwives, GPs, and other specialists for integrated care

Every pregnancy is different, and my approach ensures that you feel heard, supported, and well cared for.

Impact on the Baby

Mild to moderate Nausea & vomiting, does not usually harm the baby. However, in cases of HG or significant weight loss and dehydration, additional monitoring may be needed to ensure your baby’s growth and wellbeing.

Looking Ahead

For most women, nausea and vomiting improve by the end of the first trimester. In some, it may linger but typically becomes more manageable. Importantly, it is a temporary phase and one that can be safely managed with the right support.

If you are suffering with symptoms, you do not need to struggle alone. Please do reach out – whether it’s for reassurance, medication, or more structured treatment, I am here to guide and support you through it.

Useful Resources

• Royal College of Obstetricians and Gynaecologists (RCOG) – Green-top Guideline No. 69
• NICE Clinical Knowledge Summary on NVP
• Pregnancy Sickness Support (UK Charity) – www.pregnancysicknesssupport.org.uk

This guide is for general educational purposes and does not replace personalised medical advice. For any concerns about your pregnancy, please get in touch directly.

Dr Vinita Singh
Consultant Obstetrician
Private Practice: The Portland Hospital, London
NHS Base: Royal Free Hospital