A new study shows that taking prenatal vitamins around the time of conception- four weeks before and eight weeks after a woman’s last period- can reduce preterm (premature) births and the chances of having a smaller-than-normal baby.

The study included 36,000 pregnant Danish women who reported whether or not they had taken vitamins around the time of conception.  Among the group of women who had taken multivitamins at least eight weeks out of the 12 week period, there were 4.3 percent births before 37 weeks, while there were 5.3% preterm births among those who did not take multivitamins.

 While many studies look at supplementation during pregnancy, this study examined a unique time period- around the time of conception.  This is an especially important phase of pregnancy for a mother to have good nutrition and supplement with important vitamins and minerals- namely folic acid, iron, and calcium.

Women should begin supplementing with 400 mg per day of the B vitamin folic acid four weeks prior to conception and continue through the first trimester.  This vitamin can reduce the baby’s risk of neural tube defects such as spina bifida and anecephaly by 50-70 percent, as well as reduce the risk of other defects such as cleft palate and certain heart defects.  The body actually absorbs the synthetic form of folic acid better than it absorbs it from food sources, so supplementation is strongly recommended. Greater than 1000 mg is not recommended, though, as this amount can mask a B12 deficiency. 

Iron must also be supplemented as requirements increase from 18 to 27 mg per day during pregnancy.  A deficiency can cause anemia which increases risk of preterm delivery, low birth weight, and infant mortality.  Thirty milligrams per day is the recommended dose to prevent iron deficiency anemia. 

Lastly, a calcium supplement should be taken, which helps develop the bones and teeth of the baby as well as help it grow a healthy heart, nerves, and muscles.  If you don’t get enough in your diet, the baby will draw calcium from your bones putting you at risk for osteoporosis later on. A prenatal vitamin usually provides 150 to 200 mg of calcium- not enough to meet the1000 mg daily requirement (and 1300 mg requirement for woman 18 years old and younger). It is a good idea to take an additional 500 mg supplement separately.  Be sure not to get more than 2500 mg of calcium per day as high doses can cause constipation, increase risk of kidney stones, and affect the absorption of zinc and iron from foods.  For this reason, take your iron supplement separately from your iron pill as they affect each other’s absorption. 

And remember, it’s not only what a prenatal vitamin does have that’s important during pregnancy, but also what it doesn’t have.  It will provide no more than the recommended amounts of nutrients, especially vitamin A, which can be harmful to the baby if taken in high doses.  The supplement will provide this vitamin partly in the form of beta-carotene, the precursor to vitamin A found in plants.  Beta carotene is considered safe even in high doses. 

If you’re trying to become pregnant speak with your doctor and dietitian to find the prenatal vitamins that are right for you.  This is one of the most important times for you to back up your diet with a little “nutrition insurance”- but don’t let it replace a varied diet full of nutrient-rich fruits, vegetables, lean proteins, and whole grains!

 

Source: The American Journal of Clinical Nutrition:  http://www.ajcn.org/content/94/3/906.full

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