Overview

• Pregnancy increases magnesium needs and renal losses by roughly 20%, which can raise the risk of shortfalls despite adequate intake.
• Frequent signs include nighttime leg cramps, muscle twitching, sleep disturbance and inner restlessness, with contractions or early labor symptoms requiring prompt medical assessment.
• Serum testing detects pronounced deficiency, though tissue deficits may not always appear in blood results, and the DGE notes symptoms typically emerge below 0.5 mmol/L.
• Evidence remains split: a Cochrane review from 2014 found insufficient support for routine supplementation, while the Gesellschaft für Magnesiumforschung advises 240–480 mg daily in pregnancy.
• Current advice favors a food-first approach, keeps unsupervised supplement doses near 250 mg per day to limit diarrhea risk, and urges clinician guidance, particularly for people with kidney disease.