Magnesium is an important mineral that plays many roles in the human body. One area of interest is whether magnesium can help relax the uterus during pregnancy. The uterus is the muscular organ where a fetus develops during pregnancy. As the pregnancy progresses, the uterus grows larger to accommodate the growing baby. Contractions of the uterus are important for labor and delivery. However, premature contractions can potentially lead to preterm birth. There has been some research into whether taking magnesium supplements can help relax the uterus and prevent premature contractions and preterm birth. In this article, we’ll explore the evidence around magnesium and uterine relaxation during pregnancy.
Magnesium’s Role in the Body
Magnesium is the fourth most abundant mineral in the body. It plays several important roles including:
– Regulating muscle and nerve function
– Supporting energy production
– Synthesizing proteins
– Stabilizing cell membranes
– Regulating blood pressure
– Supporting bone health
Over 300 enzymes in the body require magnesium to function properly. It helps regulate calcium, potassium, and sodium levels as well.
Magnesium may help relax muscles throughout the body. It appears to regulate calcium flow in muscle cells, preventing over-contraction. Supplementing with magnesium has been shown to reduce muscle cramps and tension in studies.
This characteristic of magnesium has made researchers wonder if it could also help relax uterine muscles during pregnancy.
Magnesium and the Uterus
The uterus is a muscular organ made up of smooth muscle tissue. Throughout pregnancy, the uterus grows dramatically in size. Growth of the uterine muscles causes “stretching” which can trigger contractions.
Contractions of the uterus are stimulated by calcium influx into muscle cells. Magnesium may help relax the uterus by regulating these calcium channels.
By limiting calcium entry, magnesium may prevent excessive contractions and relax uterine muscles. This could potentially prevent preterm labor.
However, more research is needed to understand the exact effects of magnesium on the pregnant uterus.
Magnesium Recommendations During Pregnancy
The recommended dietary allowance (RDA) for magnesium during pregnancy is 350-400 mg per day. Good dietary sources of magnesium include:
– Green leafy vegetables
– Nuts and seeds
– Legumes
– Whole grains
– Fortified cereals
However, many prenatal vitamins do not contain 100% RDA for magnesium. Getting enough magnesium from foods alone can also be challenging.
Studies show that up to 50% of women in the US do not meet the RDA for magnesium intake during pregnancy. Deficiency in magnesium is associated with muscle cramps, migraine headaches, anxiety, and more.
Some healthcare providers may recommend magnesium supplements in addition to prenatal vitamins. Always talk to your doctor before taking any new supplements while pregnant.
Studies on Magnesium and Preterm Birth
Several studies have analyzed whether taking supplemental magnesium during pregnancy can prevent preterm birth:
– A 2018 randomized trial published in the American Journal of Obstetrics & Gynecology involved over 2,000 pregnant women at risk for preterm birth. The magnesium group took a daily magnesium citrate supplement or placebo starting at 12-20 weeks gestation until delivery. Supplemental magnesium did not lower the risk of preterm birth compared to placebo.
– A 2015 meta-analysis in the Journal of Maternal-Fetal and Neonatal Medicine combined data from 14 trials with over 6,000 pregnant women. They found that magnesium supplementation led to a 27% lower risk of preterm birth compared to control groups.
– A 1999 study in the American Journal of Obstetrics & Gynecology gave 384 pregnant women either magnesium chloride or placebo starting at 24-28 weeks gestation. The magnesium group had a lower rate of uterine contractions and less cervical changes compared to the placebo group.
– A 2018 Cochrane review evaluated data from 12 trials with over 5,700 pregnant women at risk for preterm birth. Overall, evidence was inconclusive in terms of magnesium supplementation preventing preterm birth. Larger, high-quality studies are still needed.
So the overall evidence for magnesium supplementation to prevent preterm birth is inconsistent. While some studies show a potential benefit, others show no effect. More research is still needed in this area.
Other Uses of Magnesium in Pregnancy
Aside from potential effects on the uterus, magnesium supplementation during pregnancy may provide other benefits:
Managing Preeclampsia Risk
Preeclampsia is a serious complication marked by high blood pressure and signs of damage to other organs like the kidneys or liver. It typically begins after 20 weeks gestation.
One study found that taking 300 mg of magnesium (alongside 2 grams of calcium) daily after 20 weeks may lower the risk of developing preeclampsia. Researchers believe magnesium and calcium help stabilize blood vessel function. More studies are needed though.
Controlling Glucose Levels
Magnesium may help regulate glucose metabolism and insulin sensitivity. Taking supplements may help lower the risk of impaired glucose tolerance and gestational diabetes in pregnancy.
In one study, pregnant women who took 365 mg of magnesium daily were less likely to develop gestational diabetes compared to a control group.
Alleviating Leg Cramps
Up to 50% of pregnant women experience leg muscle cramps, often at night. Magnesium supplements may help reduce cramping by regulating muscle contractions.
One study found that taking 300 mg of magnesium at bedtime significantly reduced nighttime leg cramps in pregnant women. More research is needed though.
Reducing Risk of Fetal Growth Restriction
Magnesium deficiency in pregnancy may impact placental blood flow and lead to restricted growth of the fetus.
One study showed pregnant women with higher serum magnesium levels had a 15% lower risk of the fetus being small for gestational age. More research is needed in this area.
Managing Depression and Anxiety
Magnesium plays a role in brain neurotransmitter production and neural signaling. Getting adequate magnesium intake in pregnancy may help reduce symptoms of depression and anxiety.
In one study, depressed pregnant women who took 248 mg magnesium daily had improved depression scores compared to a control group after 6 weeks.
So while the effects of magnesium on preterm birth are unclear, supplements may offer other benefits in pregnancy. Always talk to your doctor before taking new supplements.
Safety and Side Effects of Magnesium in Pregnancy
When taken in recommended dosages, magnesium is considered safe during pregnancy. The upper limit is set at 350 mg per day in addition to dietary intake.
Getting magnesium from a balanced diet is preferable to supplements during pregnancy. Food sources allow you to more easily control dosage.
Side effects of too much magnesium from supplements may include:
– Diarrhea
– Nausea
– Abdominal cramping
– Low blood pressure
Magnesium can interact with certain medications like antibiotics and diuretics. Large doses may also interfere with absorption of other minerals like calcium.
Women with kidney problems should be cautious with magnesium intake and avoid supplements. Always let your doctor know about any supplements you are taking.
Too much magnesium from supplements can be dangerous. It???s important not to exceed 350 mg per day from supplements unless directed by your doctor.
Forms of Magnesium Supplements
Magnesium supplements are available in many forms like magnesium oxide, magnesium citrate, magnesium chloride, magnesium glycinate, etc.
Some absorption and bioavailability data:
| Form of Magnesium | Absorption Rate | Bioavailability |
|---|---|---|
| Magnesium Oxide | 4% | Low |
| Magnesium Citrate | 17% | Moderate |
| Magnesium Chloride | 12% | High |
| Magnesium Glycinate | 15% | High |
Forms like magnesium glycinate and chloride tend to have higher bioavailability than magnesium oxide. Talk to your doctor about the best form for your needs.
Some magnesium supplements are labeled as “chelated” – which means the magnesium molecules are bound to proteins or amino acids that improve absorption. Chelated forms like magnesium glycinate may be preferable.
Magnesium Dosage Recommendations
The recommended magnesium intake for pregnant women over 19 years old is:
– 350-400 mg per day from food
– No more than 350 mg per day from supplements
Unless directed by your doctor, total magnesium intake from both food and supplements should not exceed 650-750 mg per day.
Deficiency is possible even with magnesium intake under 350 mg. Work with your healthcare provider to determine optimal magnesium dosage based on your health, diet, and risk factors.
Magnesium Rich Foods to Eat During Pregnancy
The best sources of magnesium are whole, unprocessed foods. Try to meet your daily needs from dietary sources instead of supplements when possible.
Good food sources of magnesium include:
Nuts and Seeds
– Almonds: 80 mg per oz
– Cashews: 74 mg per oz
– Pumpkin seeds: 151 mg per oz
– Flaxseeds: 105 mg per oz
– Sesame seeds: 101 mg per oz
Legumes
– Soybeans: 148 mg per cup
– Lentils: 71 mg per cup
– Black beans: 120 mg per cup
– Kidney beans: 74 mg per cup
Whole Grains
– Quinoa: 118 mg per cup
– Brown rice: 84 mg per cup
– Oats: 56 mg per cup
– Whole wheat bread: 46 mg per slice
Dairy and Eggs
– Yogurt: 42 mg per 8 ounces
– Milk: 37 mg per cup
– Cheese: 20 mg per oz
– Eggs: 6 mg per large egg
Leafy Greens
– Spinach: 157 mg per cup
– Collard greens: 52 mg per cup
– Kale: 24 mg per cup
– Broccoli: 12 mg per cup
Aim for a balanced diet with a variety of magnesium-rich foods. Consider tracking your intake with an app to ensure you meet daily needs.
Should You Take Magnesium Supplements to Help Relax the Uterus?
The research is still inconclusive on whether taking magnesium supplements actually prevents preterm birth. While some studies show a potential benefit, others show no effect.
More large, high-quality studies are needed. The best evidence seems to be for women at high risk for preterm birth due to issues like a history of preterm labor.
Magnesium supplements appear safe when taken in moderation during pregnancy. But getting adequate magnesium from your diet should be the priority.
Talk to your doctor about your individual risk factors for preterm birth. If you are at higher risk, your doctor may recommend a magnesium supplement as part of your care plan. The typical dose used in studies showing benefits for preterm birth prevention is around 250-500 mg elemental magnesium daily.
But magnesium supplements have not been definitively shown to relax the uterus and prevent preterm birth. More research is still needed before definitive recommendations can be made.
Bottom Line
Magnesium plays many important roles in the body and supports a healthy pregnancy. Exactly how magnesium affects the uterus during pregnancy is still unclear.
Some research shows potential for magnesium supplementation to help prevent preterm birth, especially in high-risk women. However, the evidence is not conclusive.
Magnesium supplements may offer other benefits like managing leg cramps, blood pressure, and anxiety. But getting adequate magnesium from your diet should be the priority.
Talk to your doctor about your individual health factors and risk for preterm birth. If you are at higher risk, your doctor may recommend a magnesium supplement as part of your care plan. But more research is still needed before making definitive recommendations.
Always check with your doctor before taking any new supplements during pregnancy. Focus on eating a balanced diet with good sources of magnesium. Monitor your intake to ensure you meet the RDA.
While more research is still needed, there are some promising indications that magnesium supplementation could help support uterine health during pregnancy. But for now, magnesium’s ability to definitively relax the uterus and prevent preterm birth is inconclusive.