Pregnancy comes with a long list of things to keep track of, and hydration is genuinely one of the more important ones—even if it doesn’t get as much airtime as prenatal vitamins or kick counts. The truth is, pregnant people are significantly more vulnerable to dehydration than non-pregnant people, and the consequences can go well beyond feeling sluggish.

According to Dr. Valerie A. Flores, a board-certified Reproductive Endocrinologist and Infertility Specialist at San Diego Fertility, an Ivy Fertility Center, the increased vulnerability comes down to biology. “Pregnant patients are more vulnerable to dehydration because of the increased fluid requirements in pregnancy,” she explains. “This is because of several physiological changes that happen and are specific to pregnancy—namely increases in blood volume, amniotic fluid production, and increased energy needs.”

Nausea and vomiting compound the problem for a lot of people, making it harder to take in enough fluids even when they’re trying.

Here’s what you actually need to know about dehydration during pregnancy—including the risks, the warning signs, and what to do if you think you’re falling behind.

5 dangers of dehydration during pregnancy

Mild dehydration is uncomfortable. More serious dehydration—especially if it’s tied to ongoing nausea and vomiting—can create real medical problems for both the pregnant person and the baby.

1. Kidney injury and electrolyte imbalances

When the body is significantly depleted of fluids, the kidneys are among the first organs affected. Dr. Flores notes that risks for the pregnant person include kidney injury and electrolyte imbalances involving sodium, potassium, magnesium, and chloride—all of which play important roles in how the body functions during pregnancy.

2. Vitamin deficiencies and liver complications

For people dealing with hyperemesis gravidarum—the severe form of pregnancy nausea that causes significant weight loss and dehydration—the stakes are higher. “If dehydration is related to hyperemesis gravidarum, there can also be vitamin deficiencies and problems with liver function,” Dr. Flores says.

3. Low amniotic fluid

Amniotic fluid doesn’t replenish itself from thin air—it depends in part on maternal hydration. Chronically low amniotic fluid (oligohydramnios) can lead to a range of complications, including problems with fetal development, umbilical cord compression, and in severe cases, pregnancy loss.

4. Increased risk of preterm birth (in some cases)

While the research doesn’t show a direct cause-and-effect relationship between dehydration and preterm birth generally, Dr. Flores points out that the picture changes when hyperemesis gravidarum is involved: “When dehydration is due to hyperemesis gravidarum, there is an increased risk of preterm birth.”

5. Dizziness, fainting, and electrolyte disruption

Beyond the serious medical risks, dehydration creates practical, day-to-day problems. Feeling lightheaded or faint is a direct warning sign that the body’s fluid and electrolyte balance is off—and during pregnancy, that’s not something to push through.

Early signs of dehydration in pregnancy

This is where things get a little tricky, because the early symptoms of dehydration overlap with the general misery of the first trimester (and sometimes beyond).

According to Dr. Flores, “Early signs and symptoms can include feeling excessively tired (fatigued), nauseated, dizzy or lightheaded, and/or having headaches.”

The distinguishing factor? Persistence. “While these symptoms can be related to ‘normal’ pregnancy symptoms,” she notes, “if they persist despite enough rest and treatment, then dehydration as the cause should be further evaluated.”

The more urgent red flags—the ones that mean it’s time to get medical attention rather than just drink a glass of water—are:

  • Inability to keep any food or fluids down
  • Dizziness or lightheadedness significant enough to affect daily functioning
  • Signs of significant electrolyte imbalance (confusion, muscle cramps, extreme weakness)

When to call your provider—and when to go to the ER

Dr. Flores is clear on this one. If you’re experiencing laboratory-level changes (which your provider can assess), can’t keep anything down, or are feeling faint, “patients should go to the ER for further assessment and treatment.”

Treatment in a clinical setting typically involves IV fluids, along with electrolyte and vitamin replacement when dehydration is severe. For patients whose dehydration is tied to nausea and vomiting of pregnancy or hyperemesis gravidarum, anti-nausea medications are also part of the protocol.

For milder cases that don’t require an ER visit, Dr. Flores recommends increasing fluid intake and focusing on electrolyte-rich foods and drinks. Her guidance on products: skip Gatorade and soft drinks, which don’t have the right electrolyte balance. Pedialyte is a better option.

How much water should you actually drink during pregnancy?

The general recommendation for pregnant people is 3 liters (about 13 cups) of water per day—which is slightly more than the 2.7 liters recommended for non-pregnant women. That number stays consistent across all three trimesters.

If you’re exercising, that number should go up based on the length and intensity of your workout. Same goes for hot weather, illness, or any other situation where you’re losing fluids faster than usual.

How to drink more water during pregnancy

Water aversions are real, and “just drink more water” isn’t always helpful advice when the smell or taste of plain water is making you gag. Dr. Flores offers some practical alternatives:

  • Naturally flavored or sparkling waters
  • Fruit juice mixed with water
  • Broth or soup
  • Foods with high water content: watermelon, cucumbers, yogurt

The goal is total fluid intake, not necessarily plain water specifically. If cucumber-infused sparkling water is the only thing that sounds tolerable right now, that counts.

A note on hyperemesis gravidarum

For people dealing with hyperemesis gravidarum—where nausea and vomiting are severe enough to cause weight loss and dehydration—staying hydrated at home may not be realistic. If you cannot keep fluids down for an extended period, that’s a reason to seek medical care rather than push through. IV fluids and anti-nausea medication can make a meaningful difference and in many cases are medically necessary.

Can you drink too much water during pregnancy?

Underhydration is by far the more common problem during pregnancy, but overhydration is technically possible. Drinking significantly more than the recommended daily amount can lead to symptoms including confusion and, in severe cases, seizures. The 3-liter daily guideline exists for a reason—more isn’t automatically better, unless you’re exercising or dealing with an acute illness that requires additional replacement.

FAQs about pregnancy dehydration

What are the most serious risks of dehydration during pregnancy?

For the pregnant person: kidney injury, electrolyte imbalances, and—in severe cases tied to hyperemesis gravidarum—vitamin deficiencies and liver complications. For the baby: low amniotic fluid, which can lead to developmental issues, umbilical cord problems, and in extreme cases, fetal death.

Does dehydration cause preterm labor?

The research doesn’t show a direct cause-and-effect relationship between dehydration and preterm birth in general. However, when dehydration is caused by hyperemesis gravidarum, there is an increased risk of preterm birth.

What’s the difference between normal pregnancy fatigue and dehydration?

It’s genuinely hard to tell at first, because the symptoms overlap significantly. The key differentiator is persistence—if fatigue, dizziness, or headaches aren’t improving with rest or standard pregnancy symptom management, dehydration is worth investigating.

Are electrolyte drinks safe during pregnancy?

Yes, with some caveats. Pedialyte is generally recommended over Gatorade or soft drinks, which don’t provide the right electrolyte ratios. Always check with your provider if you have questions about a specific product.

When should a pregnant person go to the ER for dehydration?

If you can’t keep any food or fluids down, are experiencing dizziness or lightheadedness, or have symptoms of significant electrolyte imbalance (confusion, extreme weakness), go to the ER. Don’t wait to see if it resolves on its own.