If you've ever been pregnant — or know someone who has — you'll be familiar with the silent suffering of morning sickness. The wave of nausea that hits before you've even got out of bed. The inability to eat. The exhaustion layered on top of exhaustion. And the well-meaning but unhelpful advice: "Just eat some crackers."

Most women are told morning sickness is just part of pregnancy — something to be endured. But nutritional status, including magnesium levels, is one of several factors researchers have looked at as a possible contributor, alongside hormonal changes and blood sugar fluctuations.

Why magnesium is worth understanding during pregnancy

Magnesium is involved in hundreds of processes in the body, from muscle and nerve function to blood sugar regulation and the nervous system's stress response. During pregnancy, magnesium requirements increase to support fetal development, placental growth, and expanded blood volume — and many women enter pregnancy with intakes that are already on the lower side, partly because modern diets and depleted soils make it harder to get enough from food alone.

Low magnesium intake has been associated in research with a range of common pregnancy symptoms, including fatigue, muscle cramps, poor sleep, and nausea — though morning sickness is a multifaceted symptom with several contributing factors, and magnesium is just one piece of that picture.

Why are so many women low in magnesium?

Magnesium is found in leafy greens, nuts, seeds, and wholegrains — but modern soils are increasingly depleted of it, meaning even a good diet may not provide enough. Add the demands of stress, caffeine, refined sugars, and the physiological work of growing a baby, and it's not surprising many women enter pregnancy already running low.

How magnesium may relate to morning sickness

Scientists are still piecing together the exact causes of morning sickness — hormonal changes, rising hCG and oestrogen levels, and blood sugar instability are all thought to play a role. Here's where magnesium's known functions come in:

It's involved in cortisol and blood sugar regulation

Magnesium plays a role in balancing cortisol — the body's primary stress hormone — and in supporting stable blood sugar. During pregnancy, cortisol can shift significantly due to hormonal changes. When blood sugar dips, nausea and dizziness can follow.

It supports the nervous system

Magnesium supports the parasympathetic nervous system — the body's "rest and digest" state. Some research has linked magnesium status to substance P, a neurotransmitter associated with nausea signalling, though this connection is still an active area of study.

It's involved in digestive muscle function

Magnesium plays a role in relaxing smooth muscle tissue, including in the digestive system. Many women also find magnesium helpful for the constipation that often accompanies early pregnancy.

It's involved in neurotransmitter regulation

Magnesium influences the release of serotonin, which plays a role in nausea signalling. Low magnesium may disrupt this balance, potentially contributing to nausea as well as the anxiety and poor sleep that often accompany it.

You are not alone

Morning sickness is real, common, and not a sign you're doing anything wrong. It's also not simply something to endure without question — nutritional status, including magnesium, is a reasonable thing to discuss with your healthcare provider if you're struggling.

Magnesium is not a guaranteed fix — morning sickness is complex and every pregnancy is different — but for many women, ensuring adequate magnesium intake is a safe, well-tolerated, evidence-supported step that supports overall wellbeing at a time when the body is working extraordinarily hard.