Ask how much water to drink in pregnancy and you get two official answers a litre apart. The European Food Safety Authority sets an adequate intake of 2.3 litres of total water a day — 300 ml more than before pregnancy, and counting the water in food. The American College of Obstetricians and Gynecologists says 8 to 12 cups of water, which is 1.9 to 2.8 litres from drinks alone. Neither is wrong. They are counting different things, and the useful number sits in the overlap.
This guide sets the two side by side, explains why pregnancy raises the need in the first place, sorts out what counts as fluid and what to limit, and gives you the signs that you are behind. It ends with the situations where "drink more" stops being enough and becomes a phone call.
The short answer. Aim for about 2 to 2.5 litres of fluid a day from drinks — eight to ten 250 ml glasses — and more when it is hot, when you exercise, when you are vomiting, and in the third trimester. All non-alcoholic drinks count. Pale-straw urine is the check; dark urine, headache and dizziness mean you are behind. Keep caffeine under 200 mg a day.
Why Pregnancy Needs More Water
1. You are making more blood
Your plasma volume — the fluid part of blood — rises by 45–55% over the pregnancy, and most of that is water. It is the largest single reason the need goes up, and it is why the third trimester, when blood volume peaks, is when falling behind shows fastest.
2. The baby lives in water
Amniotic fluid is mostly water and is not a fixed pool: it is swallowed, passed and replaced continuously. The placenta moves water across to the baby as well. None of this comes from anywhere but what you drink.
3. Everything else runs faster
Your kidneys filter more, you run slightly warmer and sweat more, and progesterone slows the gut so that more water is pulled out of what you eat — which is the mechanism behind pregnancy constipation. Then there is the bladder, which you are emptying more often than you would like, taking fluid with it.
The Official Numbers, Side by Side
| Source | What it says | What that means in drinks |
|---|---|---|
| EFSA (Europe) | 2.3 litres of total water a day in pregnancy, food included — 2.0 litres for a non-pregnant woman plus 300 ml | EFSA assumes roughly a fifth to a third comes from food, which leaves about 1.6 to 1.9 litres to drink |
| ACOG (United States) | 8 to 12 cups of water a day, or 64 to 96 fluid ounces | 1.9 to 2.8 litres from drinks |
| NHS (United Kingdom) | 6 to 8 glasses of fluid a day for adults generally, all drinks counted | About 1.6 litres as the floor, with pregnancy needing more on top |
Put together, the honest range is about two to two and a half litres from drinks for most women, with the top of the range for anyone who is heavier, more active, hotter or further along. "Eight glasses" is not a law of nature; it is a reasonable place to start.
A better starting point than a fixed number is your own body weight. A larger body carries more blood and more fluid and needs more water, which is why many clinicians and Baby Novum's tracker scale the daily goal to weight and trimester rather than handing every woman the same eight glasses.
What Counts, and What to Limit
Towards your daily total
- Water, still or sparkling, from the tap or a bottle. The cheapest and the best.
- Milk, which brings calcium and protein with it.
- Tea and coffee, within the caffeine limit — see coffee in pregnancy.
- Diluted juice, soups, and watery fruit such as watermelon, cucumber and oranges.
- Energy drinks — the caffeine and sugar are the problem; see energy drinks in pregnancy.
- Alcohol, at any amount.
- Sugary and fizzy drinks as your main fluid. They hydrate, but they also bring a lot of sugar to a pregnancy that is already managing blood glucose.
The caffeine line is 200 mg a day: the NHS puts a mug of instant coffee at about 100 mg, a mug of filter coffee at 140 mg, and a mug of tea at 75 mg, so two cups of most things fits and three of some does not. Our can-I-eat guide lists every drink with its rating by trimester.
Signs You Are Behind
- Urine colour. Pale straw is right. Dark yellow with a strong smell is the earliest and most reliable sign. The first urine of the morning is always darker; judge by the rest of the day.
- Headache that eases after a large glass of water and an hour.
- Dizziness on standing, dry mouth, and tiredness that is out of proportion to the day.
- Constipation getting worse, or hard stools.
- Fewer trips to the toilet than usual for you — a low bar in pregnancy, but a change is a change.
In hot weather and in the third trimester, thirst lags behind need. Sip through the day rather than waiting until you feel thirsty, and keep a bottle where you spend most of your time.
When the Need Goes Up
Morning sickness and vomiting
If you are vomiting, every cup you keep down is worth two you do not. Small sips every few minutes, ice chips, ice lollies and very cold water go down more easily than a glass at once. Our morning sickness guide covers what helps; if you cannot keep any fluids down for 24 hours, that is a same-day call, not something to push through.
Heat and exercise
Drink before, during and after exercise, and add a glass or two on hot days without waiting for the urine colour to tell you. Safe exercise in pregnancy is not the risk; exercising thirsty in the heat is.
The third trimester and swelling
The instinct when your ankles swell is to drink less. It is the wrong instinct: swelling in late pregnancy comes from blood volume and pressure on the veins, and cutting fluid does not reduce it. Keep drinking and put your feet up.
Water and Amniotic Fluid
A Cochrane review of four small trials in 122 women found that drinking two litres of water before a repeat scan raised the measured amniotic fluid index, in women with low fluid and in women with normal fluid. What the trials did not look at is whether that changed anything for the babies. So if a scan has shown low fluid, hydration is one part of the plan your doctor gives you — and the plan, not the water bottle, is what matters.
Timing It So You Sleep
Front-load the day. Drink most of your fluid before the late afternoon and taper over the last two hours before bed, so the bladder is not the thing waking you at 3am — our pregnancy insomnia guide covers the rest of that problem. Two small habits help more than they should: a bottle within reach wherever you sit, and water rather than tea with your iron tablets, which absorb badly with tea.
When to Call Your Doctor
Call the same day if: you cannot keep fluids down for 24 hours; you have passed no urine for eight hours or more, or very dark urine with dizziness or confusion; you have a fever with burning when you pass urine, which points to a urine infection; or your urine output drops suddenly alongside a headache, visual disturbance or swelling of the face and hands, which needs a blood pressure check.
Before 37 weeks, regular tightenings that do not settle after a large glass of water and twenty minutes on your side are a call too — see preterm labour signs.
At a Glance
Europe's EFSA says 2.3 litres of total water a day in pregnancy, America's ACOG says 8 to 12 cups, and the overlap for most women is about two to two and a half litres from drinks — more in heat, with exercise, when vomiting and in the third trimester. All non-alcoholic drinks count, caffeine stops at 200 mg, and pale-straw urine is the check. Drinking extra briefly raises amniotic fluid on a scan but is not a treatment on its own. Front-load the day so the bladder lets you sleep, and call the same day if you cannot keep fluids down or stop passing urine.
Inside Baby Novum. The hydration tracker calculates a daily water goal from your weight and trimester rather than handing you a generic eight glasses, logs each drink with one tap, fills a progress ring through the day and spaces reminders so the total arrives without you thinking about it. Premium adds the weekly chart.
Next: Constipation Relief → · Swollen Feet → · Prenatal Supplements →
Frequently Asked Questions
How much water should a pregnant woman drink a day?
The European Food Safety Authority sets an adequate intake of 2.3 litres of total water a day in pregnancy — food and drinks together, 300 ml more than before pregnancy. The American College of Obstetricians and Gynecologists says 8 to 12 cups of water, which is 1.9 to 2.8 litres. In practice that means about eight to ten 250 ml glasses from drinks for most women, and more in heat, during exercise, or when you are vomiting.
Do tea and coffee count towards my water intake?
Yes. All drinks count, including tea and coffee, milk and juice — the fluid is the fluid. What changes is what comes with it. Keep caffeine under 200 mg a day, which the NHS puts at roughly two mugs of instant coffee, and treat sugary and fizzy drinks as occasional rather than as your hydration.
How do I know whether I am drinking enough?
Look at your urine: pale straw is right, dark yellow with a strong smell means you are behind. Headache, dizziness when you stand, a dry mouth, tiredness and constipation are the other signs. How often you go is not a reliable guide in pregnancy, because you go often anyway.
Does drinking more water increase amniotic fluid?
A little, in the short term. A Cochrane review of four small trials in 122 women found that drinking two litres of water before a repeat scan raised the measured amniotic fluid index, in women with low fluid and with normal fluid. None of the trials looked at whether babies did better. If a scan has shown low fluid, hydration is one part of your doctor's plan, not a substitute for it.
Can dehydration cause Braxton Hicks or early labour?
It is widely said and the evidence for it is thin. Even so, a large glass of water and twenty minutes lying on your side is the standard first step for tightenings, and it settles most of them. What it does not settle is the point: before 37 weeks, regular tightenings that continue after fluid and rest are a same-day call.
Can you drink too much water in pregnancy?
Above what you need, extra water means more trips to the toilet, not more benefit, so there is no reason to force litres beyond thirst. The exception runs the other way: in hot weather and late pregnancy thirst lags behind need, so sipping through the day is better than waiting to feel thirsty.
Should I drink less so I stop waking up to pee?
No. Shift the timing instead: drink most of your fluid earlier in the day and taper over the last two hours before bed, and lean forward on the toilet to empty your bladder fully. Cutting your total makes you constipated and tired without buying much sleep.