Electrolytes while pregnant or breastfeeding: What you need to know

Ah, the joys of pregnancy and breastfeeding. Your body and baby crave more of just about everything: calories, protein, vitamins, minerals, sleep, and TLC. I’ve been through it twice, and I probably don’t have to tell you that it wasn’t easy. 

One thing that was particularly frustrating for me was my milk supplyOpens in a new tab while nursing my first daughter, Zoe. In retrospect, I think I may have benefited from prioritizing more salt in my diet. Conventional wisdom calls for sodium restriction during pregnancy and nursing, but conventional wisdom isn’t always right as we learn more about how our bodies work and what we need to thrive. And the research suggests sodium is important for both mother and child — supporting the mother’s health and hydration, baby’s growth, and milk productionOpens in a new tab. 

I’ll dig into that research in this article. I’ll also talk about other electrolytes like magnesium, potassium, calcium, and phosphorus. My hope in sharing what I’ve learned is to help other women navigate their own extraordinary journeys to motherhood.

Sodium Needs During Pregnancy

ElectrolytesOpens in a new tab are minerals that conduct electrical charges in the body, maintain fluid balance, aid in blood flow, support blood pressure regulation, help build bone, and influence a wide range of hormones. The research suggests that electrolyte needs (along with many other nutrientsOpens in a new tab) can increase during pregnancy and nursing.

Let’s talk about a mother’s sodium intake in the context of a developing fetus. Studies suggest that restricting sodium below 3 grams per dayOpens in a new tab may slow growth, reduce birth weight, shrink the cardiovascular system, and impair kidney function in the fetus. As a result, the baby may be more likely to develop high blood pressure later in life. So, why do some people recommend salt restriction during pregnancy? Let’s dig in. 

Salt restriction and preeclampsia risk

It’s a common belief that restricting sodium helps women avoid preeclampsia, a pregnancy complication marked by swelling of the hands/feet and high blood pressure. Preeclampsia can also impact a baby’s growth and birth weight.

It’s clear that women want to avoid preeclampsia while pregnant. But does restricting sodium actually help? Let’s review several studies on preeclampsia and salt intake:

• A 2005 Cochrane reviewOpens in a new tab found no link between salt intake and preeclampsia occurrence in 603 pregnant women. The authors conclude: “In the absence of evidence that advice to alter salt intake during pregnancy has any beneficial effect for prevention of pre-eclampsia or any other outcome, salt consumption during pregnancy should remain a matter of personal preference.”
• A 2018 reviewOpens in a new tab similarly concluded that there’s “no convincing evidence” that salt intake influences hypertension or preeclampsia risk.
• A 2019 paperOpens in a new tab did find a connection between salt intake and preeclampsia. Of 569 pregnant Danish women, those who consumed over 2.4 grams of sodium per day were slightly more likely to be diagnosed with preeclampsia than those who consumed less than that. For any stat geeks out there, the “P-value” of this effect was 0.04 — just enough to achieve statistical significance.
• A 2020 reviewOpens in a new tab following 62,774 women found that higher sodium intakes (median 3.7 grams daily) correlated with a 2% risk of developing preeclampsia during pregnancy, while low sodium intakes (median 2.6 grams daily) clocked in at 1.6%.

Overall, the data isn’t clear one way or the other. In the studies that do show an effect, the effect is small. Keep in mind, too, that observational data can be unreliable. For instance, women who eat more sodium may also eat more sugar (think processed, salty, sugary foods), and higher sugar intake is linked to higher preeclampsia riskOpens in a new tab. 

Sodium restriction can also come with its own downsidesOpens in a new tab, from increasing cortisol to triggering sodium-deficiency symptoms like headaches and muscle cramps. That said, if you’re concerned about preeclampsia while pregnant, you should consult your OB regarding your personal needs and situation.

Sodium While Breastfeeding and Beyond

After birth, electrolytes continue to support both mother and child. Sodium in particular may support a woman’s milk supply while nursing. And research suggests that getting that sodium to the baby may help with cognitive function down the road.

Sodium and milk supply

First, the milk supply point. A cool tidbit is that increasing a cow’s sodium intake boosts its milk productionOpens in a new tab. Dairy farmers love this trick. We don’t have studies on this in humans, but I’ve heard many stories from moms who insist that LMNT has increased their milk supply. I know that’s anecdotal, but it’s been such a common story that it’s hard to ignore. 

To be clear, sodium is just one piece of the milk supply puzzle. Nursing frequency, proper nutrition, and other factors play a role, too. Read our article on supporting milk supplyOpens in a new tab to go deeper.

Sodium and baby’s development

All humans need some amount of sodium for their cells to function; babies are no exception. And their sodium supply comes from breastmilk or formula.

An interesting data point is that sodium concentrations in human milk are elevatedOpens in a new tab in the early stages of breastfeeding when the milk takes the form of colostrum, the antibody-rich “first milk” that seeds the infant’s immune system. It’s possible this early hit of sodium evolved to support a child’s cognitive development. In one studyOpens in a new tab, giving salt supplements to premature infants was linked to better motor function, IQ, and memory when these kids turned 10–13. This result doesn’t mean that all babies should be given extra salt; it may only apply to premature babies. But again, it’s an interesting note.

Other Electrolytes for Pregnancy and Nursing

Besides sodium, here’s how other electrolytes can support pregnancy and nursing.

• Potassium can support blood pressure, blood sugar, and the nervous system — it can be an important electrolyte for any stage of your health journey, pregnant or not. Check our guide to potassiumOpens in a new tab to level up your knowledge here.
• Pregnancy can raise magnesium needs, and magnesium deficiency during pregnancy may affect fetal health. In one studyOpens in a new tab, pregnant women supplementing 300 mg of magnesium daily had fewer pregnancy complications than those at 100 mg/day. Learn about the benefits of magnesium hereOpens in a new tab.
• Calcium. Calcium supports bone health for mom and child. Taking calcium supplements, however, does not appear to improve bone healthOpens in a new tab in women or their babies. The “why” isn’t clear, but the evidence still supports getting calcium from dietary sources such as dairy. Here’s our guide to calciumOpens in a new tab to learn more. 

A balanced whole foods dietOpens in a new tab full of electrolyte-rich foodsOpens in a new tab is the place to start when optimizing your electrolyte intake. Don’t be afraid to test out different intakes and see what works best for you, especially in this unique stage when your body’s supporting your little one, too. You’ll feel the difference when you get it right.

My final parting advice is to try not to stress too much. There are plenty of things I wish I knew earlier in my journey to motherhood — we learn as we go, just like everybody else. On that note, I hope this article taught you something new to help you along your journey.