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Dehydration in Early Pregnancy: Signs, Risks & Treatment

Staying hydrated in pregnancy is more important than ever - and harder than ever if you're struggling with nausea and vomiting. Dehydration can develop quickly and is one of the main reasons women with hyperemesis gravidarum (HG) end up in hospital. This guide covers how to recognise dehydration, prevent it, and get help when you need it.

Table of Contents

  1. Why Hydration Matters More in Pregnancy
  2. Signs of Dehydration
  3. Causes in Early Pregnancy
  4. How Much Should You Drink?
  5. Staying Hydrated with Morning Sickness
  6. When Dehydration Is an Emergency
  7. Treatment
  8. FAQ

Why Hydration Matters More in Pregnancy

In pregnancy, your body needs more water than ever:

Increased Blood Volume

Your blood volume increases by 30-50% during pregnancy. This extra blood requires extra fluid. Dehydration can lead to low blood pressure, which causes dizziness and fainting.

Amniotic Fluid

Your body is constantly producing amniotic fluid, which is mostly water. Severe dehydration can affect amniotic fluid levels.

Kidney Function

Your kidneys work harder in pregnancy to filter extra waste from both you and your baby. Dehydration can impair kidney function and increase the risk of urinary tract infections (UTIs), which are more common and more serious in pregnancy.

Digestive Health

Water helps prevent constipation, a common pregnancy complaint. Dehydration worsens constipation and can contribute to haemorrhoids.

Temperature Regulation

Pregnancy raises your body temperature slightly. Water helps you stay cool through sweating. Dehydration can lead to overheating, which is dangerous in pregnancy.

Signs of Dehydration

### Mild Dehydration - **Thirst** - though by the time you feel thirsty, you're already slightly dehydrated - **Dark yellow urine** - aim for pale, straw-coloured urine - **Headache** - **Fatigue** - **Dry mouth and lips** - **Decreased urination**

Moderate Dehydration

  • Very dark urine (orange or brown)
  • Urinating much less frequently
  • Dizziness when standing
  • Dry skin
  • Rapid heart rate
  • Muscle cramps

Severe Dehydration (Emergency)

  • No urine for 8+ hours
  • Sunken eyes
  • Confusion or extreme drowsiness
  • Fainting
  • Rapid, weak pulse
  • Skin that doesn't bounce back when pinched
  • No tears when crying

Checking Your Hydration

The easiest way to check your hydration is your urine colour:

Urine Colour Hydration Status
Pale yellow Well hydrated
Bright yellow Mildly dehydrated
Dark yellow Moderately dehydrated
Orange/brown Severely dehydrated - seek help
No urine for 8+ hours Emergency - seek help now

Causes in Early Pregnancy

### Morning Sickness The most common cause of dehydration in early pregnancy. If you're vomiting frequently or can't keep fluids down, dehydration develops quickly. Read our guide to [morning sickness](/symptoms/morning-sickness-complete-guide).

Hyperemesis Gravidarum

Severe, persistent vomiting that prevents you from keeping any food or fluids down. This is the most common cause of severe dehydration in pregnancy. Read our HG guide.

Food Aversions

If you can't stomach water or most fluids (common with food and drink aversions), you may not drink enough without realising.

Increased Urination

Pregnancy hormones increase blood flow to the kidneys, making you urinate more often. This is normal but contributes to fluid loss.

Hot Weather

Pregnancy raises your body temperature, making you more susceptible to dehydration in hot weather.

Not Drinking Enough

Sometimes simple - you're not drinking enough water because you forgot, are busy, or are avoiding fluids to reduce nausea.

How Much Should You Drink?

### General Recommendation The NHS recommends drinking **6-8 glasses (1.6-2 litres)** of fluid per day in pregnancy. This includes water, milk, fruit juice, squash, tea, and coffee (limited to 200mg caffeine).

When You Need More

You need more fluids if:

  • You're vomiting (replace what you lose)
  • It's hot weather
  • You're exercising
  • You have a fever
  • You're breastfeeding (later in pregnancy/postpartum)

When You're Struggling with Nausea

If you can't drink large amounts:

  • Sip constantly rather than drinking glasses
  • Aim for 2+ litres spread throughout the day
  • Try ice chips and ice lollies
  • Use electrolyte solutions if you're struggling

Staying Hydrated with Morning Sickness

### Fluid Strategies - **Sip, don't gulp** - small, frequent sips are easier to keep down - **Cold fluids** are often better tolerated than warm - **Ice chips** - suck on them slowly - **Ice lollies** - homemade from diluted fruit juice - **Straws** can help some women sip more easily - **Keep water by your bed** - sip at night

Fluids to Try

  • Water - the best option
  • Diluted squash - the sugar can help when you're hypoglycaemic
  • Dioralyte (oral rehydration salts) - available from pharmacies
  • Flat lemonade or ginger ale
  • Clear broths
  • Coconut water - natural electrolytes
  • Herbal teas (peppermint, ginger, chamomile)
  • Diluted fruit juice

Foods That Hydrate

  • Watermelon (90% water)
  • Cucumber (95% water)
  • Soup (clear broths)
  • Ice lollies
  • Jelly
  • Oranges and berries

What to Avoid

  • Caffeine (limit to 200mg per day - about one mug of coffee)
  • Very sugary drinks (can worsen nausea)
  • Alcohol (avoid completely)
  • Very cold or very hot drinks if they trigger nausea

When Dehydration Is an Emergency

Go to hospital or call 999 if:
  • Can't keep any fluid down for 12-24 hours
  • No urine for 8+ hours
  • Very dark, concentrated urine
  • Dizziness or fainting
  • Confusion or extreme drowsiness
  • Vomiting blood
  • Severe abdominal pain
  • Rapid heartbeat
  • Sunken eyes
  • Skin that doesn't bounce back when pinched

These are signs of severe dehydration that needs IV treatment. Don't wait - this can be dangerous.

Treatment

### At Home (Mild Dehydration) - **Drink more fluids** - water, diluted squash, herbal tea - **Use Dioralyte** or other oral rehydration salts - **Sip ice chips** - **Rest** - **Monitor urine colour**

GP Treatment (Moderate Dehydration)

  • Anti-sickness medication to stop vomiting
  • Monitoring of weight and urine
  • Blood tests for electrolytes
  • Advice on managing fluids

Hospital Treatment (Severe Dehydration)

  • IV fluids - the most effective treatment
  • IV anti-sickness medication
  • Blood tests and monitoring
  • Vitamin supplementation (especially thiamine)
  • 1-3 day stay typically

After Treatment

  • Continue anti-sickness medication as prescribed
  • Sip fluids constantly
  • Monitor urine colour
  • Rest
  • Ask for help at home

Frequently Asked Questions

### How do I know if I'm dehydrated in pregnancy?

The easiest way to check is your urine colour. Pale yellow means you're well hydrated; dark yellow or orange means you're dehydrated. Other signs include headache, dizziness, dry mouth, and infrequent urination.

How much water should I drink in pregnancy?

The NHS recommends 6-8 glasses (1.6-2 litres) of fluid per day. If you're vomiting or it's hot, you need more. Sip throughout the day rather than drinking large amounts at once.

What should I do if I can't keep water down?

Contact your GP or call 111 immediately. You may need prescription anti-sickness medication or IV fluids. Not being able to keep water down for 12+ hours is a sign of hyperemesis gravidarum and needs medical treatment.

Is dehydration dangerous in pregnancy?

Yes, severe dehydration can be dangerous. It can cause electrolyte imbalances, low blood pressure, kidney strain, and may affect amniotic fluid. Seek medical help if you can't keep fluids down or have signs of severe dehydration.

Can I drink Dioralyte in pregnancy?

Yes, Dioralyte and other oral rehydration salts are safe in pregnancy. They're available from pharmacies without a prescription and can help replace electrolytes lost through vomiting. However, if you can't keep them down, you may need IV fluids.

Further reading:

This article is for informational purposes only and does not constitute medical advice. Always consult your GP or midwife with any concerns about your pregnancy.

Last reviewed: June 2026

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