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Vitamin D Deficiency in Pregnancy Could Lead to Risk of Language Problems for Children

Vitamin D Deficiency and Pregnancy, Pregnancy Nutrition

Vitamin D is one of the most studied vitamins of recent times, as it appears that there is widespread deficiency that leads to multiple health issues. A particular group that may not be receiving enough of the vitamin is pregnant women. Not only do they risk conditions such as preeclampsia and gestational diabetes when deficient, but their children are also at risk for low birth weight, asthma, and – in a new finding – future language delays.

Andrew Whitehouse PhD of the University of Western Australia’s Telethon Institute for Child Health Research and colleagues assessed data collected in the Western Australian Pregnancy Cohort (Raine) Study conducted in Perth. The study included 743 white women who provided blood samples at 18 weeks gestation, a key time for fetal neurodevelopment. The researchers tested for 25-hydroxy vitamin D, the most accurate measure of the body’s vitamin D status.

The researchers followed up with the offspring born to the women at ages 2, 5, 8, 10, 14, and 17 using the Child Behavior Checklist. At ages 5 and 10, the children were tested for receptive language skills using the Peabody Picture Vocabulary Test-Revised.

Overall, there was no correlation between maternal vitamin D status and any behavioral or emotional behaviors in the children. However, children born to women whose 25(OH)D levels were less than 46 nmol/L in the second trimester were nearly twice as likely to have clinically significant language problems.

The Australian study uses SI units (international units) as its measure for vitamin D status. The National Institutes of Health uses conventional units, or ng/mL. To convert the findings to data that would correlate better to American guidelines, we need to divide by a conversion factor of 2.496 – meaning women whose vitamin D status was below 18.4 ng/mL would be at greater risk for having children with language delays. This is significantly below the normal reference range for 25(OH) D which is 30.0-74 ng/mL.

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Vitamin D is important in neurodevelopment, including “a signaling role in neuronal differentiation, a regulation role in the metabolism of neurotrophic factors and neurotoxins, and a protective role during brain inflammation." The vitamin may also be involved directly in fetal brain growth.

"Randomized controlled trials of vitamin D supplementation are required to verify these observational data that suggest that an adequate maternal vitamin D status during pregnancy is necessary for optimal language development in offspring," says Dr. Whitehouse.

The recommendation for vitamin D intake during pregnancy by the Institute of Medicine is 600 IU each day. Being compliant with prenatal vitamins that contain Vitamin D may help prevent health issues in both mother and child. Most contain 1,200 IU; those deficient may need additional supplementation.

Foods that contain vitamin D include milk, egg yolks, fish (swordfish, salmon and tuna) and fortified cereals and beverages (such as orange juice or soy milk).

Exercising outdoors is also a good way to obtain vitamin D. This vitamin is the only one the body can make on its own using UV rays from sunlight. A previous study has found that those who exercise outdoors often have higher levels of vitamin D.

Journal reference:
Whitehouse A, et al. "Maternal serum vitamin D levels during pregnancy and offspring neurocognitive development"Pediatrics 2012; DOI: 10.1542/peds.2011-2644.

Other Resources:
25-hydroxy vitamin D test. Medline Plus, a service of the US National Library of Medicine and the National Institutes of Health.
The Clinician’s Ultimate Reference Guide – Table of Conversion from Conventional Units to International Units
Office of Dietary Supplements, National Institutes of Health, “Dietary Supplement Fact Sheet – Vitamin D”