Electrolytes during pregnancy and breastfeeding: 7 things to know

• Where we stand: we’re not doctors, so it isn’t our place to recommend or rule out any product for you. We show what the limited research says and how our products compare, so you and your doctor can decide.
• Fluid needs rise. Roughly 3.0 litres of total water a day in pregnancy and 3.8 litres while breastfeeding. Water in food counts.
• Most electrolytes should come from food. Sodium, potassium and magnesium all have official daily targets.
• Sodium: the adequate intake is 1,500 mg a day, the same as other adults. Don’t chase it or fear it, and follow your doctor if you have blood pressure concerns.
• If you can’t keep fluids down, that’s a medical issue. Get help straight away.
• Heat, exercise and surfing need extra thought. Heat matters in the tropics, and ACOG’s list of higher-risk activities names surfing. We found no studies of surfing in pregnancy, so that call is for you and your provider.
• The evidence is thin that magnesium helps leg cramps, and extra water hasn’t been shown to boost milk supply.
• We found no research on electrolyte drink mixes themselves in pregnancy or breastfeeding. Ask your doctor before trying any, including ours.

One of our ambassadors, who owns a café, got in touch with a question: what do electrolytes do during pregnancy and breastfeeding? We didn’t know the answer.

We want to be upfront about what we are and aren’t. We are not doctors, gynaecologists or obstetricians. None of this is medical advice. Because we couldn’t answer her, we did what we’d want someone to do for us: we found the research, so she could read it and talk to her own doctor.

Below is what major health bodies and published studies say, and where the evidence runs out. We know this is a slippery slope, so please treat it as a starting point for a conversation with your doctor, midwife or lactation consultant, not as a recommendation.

Pregnancy and breastfeeding both raise how much fluid your body needs. The US National Academies estimate adequate total water intake at about 3.0 litres a day in pregnancy (around 2.3 litres of that from drinks, roughly 10 cups) and about 3.8 litres a day while breastfeeding (around 3.1 litres from drinks, roughly 13 cups). “Total” includes the water in food. For comparison, the figure for women who are neither pregnant nor breastfeeding is about 2.7 litres.

These are estimates for healthy people, not targets or prescriptions. Your own needs depend on heat, activity and your health, and your doctor or midwife is the right person to tell you what’s right for you.

Sodium, potassium and magnesium are the three people ask about most. These are the official reference figures for women aged 19 to 50, per day, from all sources combined.

Sodium and potassium figures are “adequate intakes” (National Academies, 2019). Magnesium figures are recommended dietary allowances (NIH Office of Dietary Supplements).

Two details matter. The sodium advice also says to cut back if you regularly eat more than 2,300 mg a day. And for magnesium, the upper limit of 350 mg a day applies to supplements and medicines, not to magnesium in food.

Vegetables, fruit, legumes, nuts and whole grains are major sources of potassium and magnesium, so for most people a varied diet does much of the work.

Sodium is essential, and pregnant and breastfeeding women have the same adequate intake as other adults: 1,500 mg a day. The National Academies didn’t set an upper limit for sodium, but advise cutting back if you’re regularly above 2,300 mg a day, because high intakes are linked to higher blood pressure.

In pregnancy specifically, a Cochrane review found that advice to eat less salt did not prevent pre-eclampsia, and concluded that salt intake in pregnancy can be a matter of personal preference. That review is small and old (two trials, 603 women, published in 2005), and it’s about prevention in general. If you have high blood pressure, swelling, or have been told to watch your salt, follow your doctor’s advice, not a general summary like this one.

A note on our own product. Hardcore has 1,000 mg of sodium per serve, which is about two thirds of the 1,500 mg adequate intake in a single drink. We built it for heavy sweating in the tropics, not for pregnancy. We ask everyone with a medical condition to speak to their doctor first, and for pregnancy and breastfeeding we’d say the same.

Morning sickness is common. Hyperemesis gravidarum is the severe form, where you can’t keep food or liquid down. NHS hospital guidance describes treatment as fluids given into a vein, plus blood tests to check for electrolyte imbalance, and tells women who can’t keep fluids down to seek urgent medical help.

A drink mix is not a substitute for that care. If you can’t keep fluids down, call your doctor, midwife or hospital straight away.

ACOG advises that during exercise, pregnant women should stay well hydrated, wear loose-fitting clothing and avoid high heat and humidity to protect against heat stress, particularly in the first trimester. That matters in places like the Philippines. A 2025 review in Nature Medicine pooled 198 studies and found higher odds of preterm birth with more heat exposure: about 4% higher per 1°C, and 26% higher during heatwaves. It measured outdoor heat rather than exercise, and most of its studies were from temperate countries, so it isn’t a rule for any single session. It is a good reason to take heat seriously.

Surfing. ACOG’s guidance steers away from activities with a higher risk of falls or a blow to the abdomen. Summaries of that list, including one from Lamaze International, name surfing and water skiing. We found no formal studies of surfing in pregnancy, so the advice comes from general exercise guidance, and plenty of surfers do keep surfing for a while with their provider’s agreement. We can’t make that call for you. Worth raising with your provider: how far along you are, the risk of a fall or a board hitting your belly, heat and session length, and how crowded the break is.

Sodium and sweat. We couldn’t find pregnancy-specific guidance on replacing the sodium you lose in sweat. Sweat rates and saltiness vary a lot between people, so we can’t give you a number, and neither can a drink label. If you sweat heavily, ask your doctor before you decide what to drink.

Leg cramps are common in pregnancy, and magnesium is the usual suggestion. The most recent Cochrane review (2020) found inconsistent results and concluded that it’s unclear whether magnesium, calcium or any of the other options tested is an effective treatment. Magnesium may make little to no difference to how often cramps happen.

If you’re thinking about a magnesium supplement, remember the 350 mg a day upper limit for magnesium from supplements, and ask your doctor first.

Breastfeeding raises your fluid needs, and many mothers feel thirstier. A Cochrane review of extra fluids for breastfeeding mothers found one trial, in which advising extra fluids did not increase milk production, and concluded the effect remains unknown because of a lack of well-conducted trials. There isn’t enough evidence to support drinking beyond what your body needs.

On sodium: in a small 1987 study of eight breastfeeding mothers, a very low-sodium lunch (130 mg) and a high-sodium lunch (2,175 mg) made no significant difference to the sodium or potassium in their milk. A 2020 study of 64 mothers also found that milk sodium wasn’t directly driven by what they ate. Both studies are small, so treat them as reassurance, not proof.

If you notice signs of dehydration that don’t improve, a sudden drop in milk supply, a fever, or a hot, painful, red area on the breast, speak to your doctor or lactation consultant.

Here’s how each of our products lines up against the pregnancy reference values in section 2, per serve. This is a comparison, not a recommendation either way. We’re not doctors, so it isn’t our place to tell you to use or avoid any product. We’re showing you the numbers and what the limited research says, so you can take them to your doctor. If your doctor says no, the answer is no. We left out our caffeinated blend, because caffeine has its own limit during pregnancy (see below).

Percentages compare one serve (a 6 g scoop) with the pregnancy reference values in section 2 (sodium 1,500 mg, potassium 2,900 mg, magnesium 350 mg). Hardcore and Daily Driver figures come from their labels. Sunset Session is still in development, so its figures may change. Magnesium from supplements also has a 350 mg a day upper limit, and that counts anything else you take, such as a prenatal vitamin.

Caffeine: ACOG says moderate caffeine (under 200 mg a day) does not appear to be a major factor in miscarriage or preterm birth, though a final conclusion can’t be made about high intakes, and some reviews advise avoiding caffeine altogether. If you’re pregnant, count caffeine from every source and ask your doctor what’s right for you.

We didn’t find studies of electrolyte drink mixes themselves in pregnancy or breastfeeding. The figures above are for nutrients from all sources, mostly food. That gap is the main reason to ask your doctor before you try any product, including ours.

Read the label for:

• Sodium per serve, compared with the 1,500 mg adequate intake in section 2.
• Magnesium per serve, compared with the 350 mg a day upper limit for supplemental magnesium.
• Caffeine. ACOG says moderate caffeine (under 200 mg a day) does not appear to be a major factor in miscarriage or preterm birth, but a final conclusion can’t be made about high intakes, and some reviews advise avoiding caffeine altogether.
• Everything else: sweeteners, herbal extracts and anything labelled “energy” or “detox”. Ask your doctor about each one.

Questions to take to your doctor:

• Do I have a condition (blood pressure, kidneys, swelling) that changes my sodium, potassium or magnesium targets?
• How much fluid should I aim for, given where I live and how active I am?
• If I’m vomiting, at what point should I come in?
• Is there anything in the products I’m using that I should avoid right now?