Vitamin D During Pregnancy Essential for Brain Development of Fetus, Researchers Say

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Vitamin D is already considered crucial for pregnant mothers; it helps aid in bone formation of the fetus. But researchers from the Center for Research in Environmental Epidemiology in Barcelona are now saying that vitamin D is even more important than previously thought. After a recent study, they believe that vitamin D is also important for brain function later in life.

The Spanish researchers evaluated nearly 2,000 pregnant women over the course of their study. During the first or second trimester, vitamin D blood levels were measured. Approximately 20 percent of those women were considered to be vitamin D-deficient by the researchers. Another 32 percent were said to have insufficient levels of vitamin-D.

After the pregnancies were completed, the researchers then conducted evaluations on the children born to those mothers; all of the children were around 14 months of age at the time of testing.

According to their data, children born to mothers “deficient” in vitamin D scored 2.6 points lower on a mental test and 2.3 points lower on a psychomotor test than children born to mothers who had a sufficient amount of vitamin D during pregnancy. This was found to be true even after the researchers accounted for maternal age at the time of conception, mother’s educational level, birth weight, social class, and whether or not the mother smoked or drank during pregnancy.

While the differences may not make a big difference on an individual level, researchers believe the reduction of four and five points in these types of neuropsychological tests could reduce the number of children with above-average intelligence scores by 50 percent.

“These differences in the mental and psychomotor developmental scores do not likely make any difference at the individual level, but might have an important impact at the population level,” said lead author Dr. Eva Morales, medical epidemiologist in the Center for Research in Environmental Epidemiology in Barcelona.

But how much is enough? It seems there’s a bit of a debate on that.

The Institute of Medicine, an independent U.S. group that advises the public on health, says that pregnant women should get at least 600 international units (IU) per day of vitamin D, and that they should take no more than 4,000 IU per day.

The Endocrine Society says that 600 IUs per day just isn’t enough. They believe that the minimum amount should be closer to 1,500 to 2,000 IUs per day.

Bruce Hollis, director of pediatric nutritional sciences at the Medical University of South Carolina in Charleston agrees. He says that 600 IUs per day may be sufficient for promoting good bone health in children, but that level “basically does nothing” to prevent other diseases. He’s done previous studies that suggest higher amounts of vitamin D might help reduce the chances of high blood pressure and pregnancy-related diabetes.

Hollis says vitamin D levels should fall around 4,000 IUs for women who are pregnant or trying to conceive. Just to grasp how much vitamin D that actually is…Hollis says that it would be impossible to intake that much on dietary foods alone. He suggests 10-15 minutes of sunlight per day for fair-skinned individuals. Hollis also says that earlier studies regarding high levels of vitamin D and birth defects were bogus. He says that women can receive up to 50,000 IUs per day without having to worry about issues like spiked calcium levels, which can lead to nerve damage, abnormal heart rhythms and kidney damage.

Of course, not everyone is fully convinced on the evidence presented in the recent study. Dr. Ruth Lawrence, medical director of the Breastfeeding and Human Lactation Study Center at the University of Rochester Medical Center in New York doesn’t refute the importance of vitamin D.

“We have realized that vitamin D has a lot more impact than to prevent rickets,” Lawrence said.

She does not believe, however, that this study shows sufficient evidence to claim that brain function is impaired by a lack of vitamin D.  She says the authors could get a better idea of just how much brain function is disrupted by vitamin D deficiency if they evaluated the children again at 7 or 8 years of age, right around the time the children would be learning how to read and write. She also pointed out that the study failed to look at the diet of the infants after birth.

Vitamin D can be found in both breast milk and in formula. However, only breast milk contains healthy cholesterol and the amino acid taurine. Lawrence says that these two ingredients are very important for brain function as well.

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About the Author

Kate Givans is a wife and a mother of five—four sons (one with autism) and a daughter. She’s an advocate for breastfeeding, women’s rights, against domestic violence, and equality for all. When not writing—be it creating her next romance novel or here on Growing Your Baby—Kate can be found discussing humanitarian issues, animal rights, eco-awareness, food, parenting, and her favorite books and shows on Twitter or Facebook. Laundry is the bane of her existence, but armed with a cup of coffee, she sometimes she gets it done. Find out more about Kate’s books at

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