Pregnancy Hydration: How Much Water Do Pregnant Women Need?

Pregnancy dramatically increases a woman's need for water. The body must produce amniotic fluid, support a 50 percent increase in blood volume, build new tissue, and prepare for breast milk production — all of which require significant additional fluid. This guide explains how much water pregnant and breastfeeding women need, signs of dehydration in pregnancy, which beverages to choose, and which to avoid.

Why Hydration Matters More During Pregnancy

During pregnancy, a woman's blood volume increases by approximately 50 percent to support the growing fetus and placenta. This extra blood requires additional water. Amniotic fluid, which surrounds and protects the fetus, is renewed every few hours and is composed almost entirely of water. The placenta itself is mostly water, and the developing fetus is about 75 percent water. All of this means that pregnant women need significantly more fluid than non-pregnant women.

Adequate hydration during pregnancy is associated with a lower risk of several complications. Studies have linked dehydration to an increased risk of urinary tract infections (which are more common and more serious during pregnancy), constipation (already a common pregnancy complaint), swelling, hemorrhoids, and even preterm labor in some cases. Severe dehydration can reduce amniotic fluid levels (oligohydramnios), which can affect fetal development.

Hydration also plays a role in managing common pregnancy discomforts. Drinking enough water helps reduce morning sickness, prevents constipation, reduces swelling in the legs and ankles, helps regulate body temperature (which tends to run higher during pregnancy), and may reduce the risk of headaches. Many pregnant women find that staying well-hydrated significantly improves how they feel day to day.

How Much Water Do Pregnant Women Need?

The Institute of Medicine recommends that pregnant women consume about 3.0 liters (100 ounces) of total water per day from all beverages and foods combined. This compares to 2.7 liters for non-pregnant women — an increase of about 300 ml per day. For breastfeeding women, the recommendation increases to 3.8 liters (128 ounces) per day to support milk production, which requires roughly 700 to 1,000 ml of additional fluid daily.

Individual needs vary based on body size, activity level, climate, and the stage of pregnancy. Women in their third trimester may need more water than those in their first trimester due to the larger fetal size and blood volume. Women carrying twins or higher-order multiples have even higher fluid needs. Women who exercise or live in hot climates need additional water to replace sweat losses.

A simple way to estimate your needs is to use our Pregnancy Water Intake Calculator, which adjusts the baseline for pregnancy or breastfeeding status. As a general rule, aim for at least 8 to 12 cups (1.9 to 2.8 liters) of beverages per day, with the rest coming from food. Monitor urine color — pale straw indicates good hydration.

Signs of Dehydration During Pregnancy

Pregnant women should be vigilant about recognizing dehydration, which can develop more quickly during pregnancy due to the increased fluid demands. Mild dehydration may cause thirst, dry mouth, headache, dizziness (particularly when standing, as blood pressure tends to be lower during pregnancy), dark yellow urine, reduced urination, and constipation.

More severe dehydration can cause rapid heartbeat, low blood pressure, confusion, fainting, and reduced fetal movement. If you experience any of these severe symptoms, contact your healthcare provider immediately. Severe dehydration during pregnancy can lead to complications including reduced amniotic fluid, preterm contractions, and in extreme cases, preterm labor.

Pregnant women with hyperemesis gravidarum (severe morning sickness with persistent vomiting) are at particularly high risk of dehydration and may require intravenous fluids. If you cannot keep fluids down for more than 12 hours, contact your healthcare provider. Signs that warrant immediate medical attention include dark urine or no urination for 8 hours, dizziness or fainting, rapid heartbeat, severe headache, and reduced fetal movement.

Beverages to Choose and Avoid During Pregnancy

The best beverage during pregnancy is plain water, which should make up the majority of fluid intake. Sparkling water, milk (which also provides calcium and protein), and 100 percent fruit juice in moderation (limit to 1 small glass per day due to sugar content) are also good choices. Herbal teas can be consumed in moderation, but some herbs are not safe during pregnancy — check with your healthcare provider before drinking herbal teas regularly.

Caffeine intake should be limited to no more than 200 mg per day during pregnancy (about one 12-ounce cup of coffee), according to the American College of Obstetricians and Gynecologists. High caffeine intake has been associated with an increased risk of miscarriage and low birth weight in some studies. Keep in mind that caffeine is also found in tea, chocolate, energy drinks, and some medications.

Alcohol should be avoided completely during pregnancy. No amount of alcohol has been proven safe during pregnancy, and prenatal alcohol exposure is the leading preventable cause of birth defects and developmental disabilities. Avoid unpasteurized juices and milk, which can contain harmful bacteria like Listeria and E. coli. Limit sugary drinks, which add empty calories and can contribute to gestational diabetes and excess weight gain.

Practical Tips for Staying Hydrated During Pregnancy

Carry a water bottle with you everywhere. The simple act of having water within reach dramatically increases intake. Drink a glass of water with each meal and snack. Add slices of lemon, lime, cucumber, or fresh mint to make water more appealing if plain water triggers nausea. Sip slowly rather than gulping, which can worsen morning sickness. If you are struggling with nausea, try drinking water between meals rather than with meals, as large amounts of fluid with food can trigger vomiting.

Eat water-rich foods like watermelon, cucumber, oranges, and soups, which contribute to fluid intake without filling you up too much. This is especially helpful in the third trimester when the growing uterus compresses the stomach and makes large meals uncomfortable. Avoid drinking large amounts of water right before bed to minimize nighttime bathroom trips, but drink adequately throughout the day.

If you are exercising during pregnancy (which is generally recommended for healthy pregnancies), drink extra water before, during, and after activity. Pregnancy raises your core body temperature slightly, and exercise increases it further, so hydration is especially important to prevent overheating. Avoid exercising in hot, humid conditions, and stop immediately if you feel dizzy, lightheaded, or overheated.

Breastfeeding Hydration

Breastfeeding women have even higher fluid needs than pregnant women — about 3.8 liters per day from all sources. Breast milk is about 87 percent water, and producing 750 to 1,000 ml of milk per day requires roughly 700 to 1,000 ml of additional fluid intake. Many breastfeeding women notice increased thirst during and after feeding, which is the body's natural signal to drink more.

A simple strategy is to drink a glass of water every time you nurse or pump. Keep a water bottle near where you typically nurse. Monitor urine color — pale straw indicates good hydration. If you notice a decrease in milk production, increasing fluid intake is one of the first interventions to try (though other factors like frequency of nursing, stress, and sleep also affect milk supply). Avoid excessive caffeine while breastfeeding (limit to 200 to 300 mg per day), as some caffeine passes into breast milk and can affect the baby's sleep.

For personalized hydration targets during pregnancy or breastfeeding, use our Pregnancy Water Intake Calculator. And for general hydration guidance applicable to all adults, see our Daily Water Intake Calculator. Always discuss your specific hydration needs with your healthcare provider, particularly if you have any pregnancy complications or medical conditions.