Magnesium May Help Moms-to-Be Maintain Healthy Blood Pressure

Magnesium May Help Moms-to-Be Maintain Healthy Blood Pressure: Main Image
Compared with the placebo group, the magnesium group experienced significantly lower blood pressure
Maintaining healthy blood pressure levels—defined as less than 120/80—is an important part of a healthy pregnancy. Yet some expectant moms experience unhealthy increases in blood pressure, especially during the last weeks of pregnancy. Magnesium, an inexpensive mineral supplement, may help pregnant women minimize these blood pressure changes.

More magnesium for new moms

Researchers randomly selected 61 first-time pregnant women to take a daily 300 mg magnesium supplement or no magnesium (placebo pill), beginning at the 25th week of pregnancy. They continued supplementing through delivery, and blood pressure was monitored throughout the study. Urinary magnesium excretion—the amount of magnesium in a standardized urine sample—was measured at the 25th and 37th weeks of pregnancy.

  • Compared with the placebo group, the magnesium group experienced significantly lower blood pressure by the 37th week of pregnancy; the average diastolic blood pressure (lower number) in the magnesium group was 72 vs. 77 in the placebo group.
  • More women in the placebo group experienced a diastolic blood pressure increase of 15 or greater compared with women in the magnesium group.

Mastering dietary and supplemental magnesium

This study was small, and did not collect any information on dietary (food) magnesium sources. Still, it points to the importance of getting enough magnesium to ensure a healthy pregnancy. Our tips will help you factor the mineral into your pregnancy plans:

  • Ask your doctor. Always ask your doctor before taking any new supplements. This is especially important for pregnant women, to avoid accidentally taking things that may harm a developing fetus.
  • Avoid self-treating. If a pregnant woman’s blood pressure reaches 140/90 and is accompanied by protein in the urine, the condition is diagnosed as pre-eclampsia, which can lead to eclampsia, a potentially fatal condition for both mother and baby. Do not self-treat high blood pressure with magnesium; take only if directed by your doctor to do so.
  • Master moderation. The recommended dietary allowance (RDA) for magnesium ranges from 350 to 400 mg per day for pregnant women, depending on age. The study used 300 mg of magnesium in citrate form, a moderate dose that doesn’t reach the RDA for pregnant women of any age.
  • Note side effects. Magnesium can act as a laxative, causing loose stools. Many pregnant women experience constipation during pregnancy, so this may be a welcome side effect. However, chronic loose stools can upset electrolyte balance, which is dangerous for you and your baby. Talk to your doctor before you begin magnesium supplements.
  • Focus on food. Good food sources of magnesium, without the side effects seen in supplements, include whole grains—particularly buckwheat, bulgur wheat, oat bran, and wheat bran—nuts and seeds, beans and lentils, dark green leafy vegetables, bananas and raisins, potatoes and sweet potatoes, and dark chocolate—a favorite of pregnant and non-pregnant women everywhere!

(Arch Gynecol Obstet 2013; doi:10.1007/s00404-013-2900-2)

Suzanne Dixon, MPH, MS, RD, an author, speaker, and internationally recognized expert in chronic disease prevention, epidemiology, and nutrition, has taught medical, nursing, public health, and alternative medicine coursework. She has delivered over 150 invited lectures to health professionals and consumers and is the creator of a nutrition website acclaimed by the New York Times and Time magazine. Suzanne received her training in epidemiology and nutrition at the University of Michigan, School of Public Health at Ann Arbor.

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