Hydration During Pregnancy: How Much and Why It Matters More

Hydration doesn’t get as much attention as food safety or specific nutrients in pregnancy advice, but it plays a genuinely important role — supporting the increased blood volume of pregnancy, amniotic fluid levels, digestion, and helping manage common pregnancy complaints like constipation and swelling.

Why Fluid Needs Increase

Your blood volume expands by up to 50% during pregnancy, and amniotic fluid — which surrounds and protects your baby — is largely water, continuously produced and replaced. Both of these increase your body’s baseline fluid requirement above pre-pregnancy levels.

How Much to Aim For

Around 8-10 glasses (roughly 1.6–2 litres) of fluid a day is a commonly cited general guide, though needs increase further in hot weather or with physical activity. This doesn’t need to be exclusively water — herbal teas within the guidance covered on this site, diluted juice, milk, and the fluid content of soups and fruit all count toward your total. Thirst is a reasonably reliable guide for most women, but it’s worth being deliberate about fluid intake rather than relying on thirst alone, since it’s easy to under-drink during a busy day.

Signs You Might Not Be Drinking Enough

• Dark yellow urine (pale straw-coloured is the sign of good hydration)
• Headaches
• Dizziness or feeling faint
• Constipation
• Reduced urination frequency

Hydration and Common Pregnancy Complaints

Constipation — fibre without adequate fluid can actually make constipation worse rather than better, since fibre needs water to do its job effectively (see our constipation and fibre guide).

Swelling (oedema) — counterintuitively, drinking more water can help reduce fluid retention and swelling in the hands, feet, and ankles that many women experience, particularly in the third trimester, because dehydration can actually prompt the body to retain fluid more aggressively.

UTIs — pregnancy increases the risk of urinary tract infections, and good hydration is one of the simplest preventive measures, helping flush bacteria from the urinary tract.

Braxton Hicks contractions — dehydration is a recognised trigger for these practice contractions; some women find that drinking a glass of water settles them.

When Plain Water Feels Unappealing

Some women, particularly with nausea in the first trimester, find plain water genuinely hard to tolerate. Practical alternatives that still count toward hydration:

• Water with fresh lemon, lime, cucumber, or mint added
• Sparkling water
• Diluted squash or fruit juice
• Herbal teas known to be safe in pregnancy, served warm or chilled
• Ice lollies or ice chips, particularly helpful if nausea makes drinking difficult
• Water-rich foods — cucumber, watermelon, soup — which contribute meaningfully to overall fluid intake

Caffeinated Drinks and Hydration

Tea, coffee, and other caffeinated drinks do still contribute to fluid intake despite caffeine’s mild diuretic effect — the old idea that they cause net dehydration isn’t well supported by current evidence. That said, they still count toward the separate 200mg daily caffeine limit covered in our caffeine guide, so it’s worth thinking of them as one part of your fluid intake rather than the whole of it.