A flurry of recent research has now confirmed that the sun is not only healthy, but it is necessary for pregnant mothers and the health of their babies.
While so many health professionals now recommend the slathering on of toxic sunscreen in fear of skin cancer, more research is illustrating that vitamin D – produced by the body naturally with exposure to the sun’s UVB rays – is needed for a newborn’s health.
This realization was recognized by Chinese hospital researchers who measured the relationship between the vitamin D status of pregnant women and the eventual birth weights of their infants in Beijing. The researchers found that babies born of women with severe vitamin D deficiency within the blood and umbilical cord blood had significantly lower birth weights and shorter body lengths than baby’s born of women with higher vitamin D status.
The researchers also found that baby’s born of mothers with lower vitamin D status also had smaller head circumference.
This research confirms a larger and more recent study to be published in the Journal of Clinical Endocrinology and Metabolism by scientists from the University of Pittsburgh Graduate School of Public Health.
In this study, the medical records of 2,146 mothers from 12 medical centers in the United States between 1959 and 1965 were examined. The testing measured the mothers’ vitamin D status and the relative birth weights of their babies, along with their Ponderal Index, which measures the relative lean weight by comparing weight to body length (height), and head circumference – linked with the baby’s ongoing cognitive development and growth.
This study confirmed that mothers with lower levels of vitamin D had children with lower birth weights and smaller head circumferences. On average, serum vitamin D levels (25(OH)D) of 37.5 nmol per liter or greater resulted in an average of 46 grams greater birth weight and 0.13 centimeter greater head circumferences.
The researchers concluded that, “maternal vitamin D status is independently associated with markers of physiological and pathological growth in term infants.”
The study was led by Dr. Alison Gernand, a professor at the University of Pittsburgh. “A mother’s vitamin D level early in pregnancy may impact the growth of her baby later in pregnancy,” commented Dr. Gernand.
Another recent study has found that a baby’s bone volume is directly associated with the vitamin D status of the mother. In this study, 357 pregnant women and their resulting babies were studied. The mother’s blood was tested, and the ultrasound measurements of their babies’ femurs were analyzed to determine the baby’s relative bone volume.
This study found that the mother’s vitamin D status was directly related to the femur bone volume of the baby. Vitamin D status was also linked with baby size and skinfold status, confirming the same results as found in the two studies mentioned above.
It is one thing to present that a mother’s vitamin D status affects her baby’s growth in early life. It is another to find that the baby’s ongoing metabolism is affected by vitamin D status.
Yet this is precisely what two other recent studies have found.
Researchers from the University College Dublin’s Medical School measured levels of vitamin D in the blood (25-hydroxyvitamin D or 25-OHD) with markers of glucose metabolism health, including glucose, insulin, C-peptide and leptin among mothers during their early pregnancy and again at 28 weeks gestation. This was assembled into the equation called the Homeostasis Model Assessment (HOMA), which measures insulin resistance.
The researchers found that the babies of those mothers with lower vitamin D had higher levels of HOMA – meaning greater levels of insulin resistance.
This relationship was confirmed by another recent study, this from researchers at Boston’s Beth Israel Deaconess Medical Center. In this study researchers examined the relationship between a mother’s vitamin D levels and the tendency for diabetes in pregnancy– also termed gestational diabetes mellitus. The researchers tested 159 pregnant women and their babies and found that those mothers with lower vitamin D levels had more than double the risk of gestational diabetes mellitus.
Other research has found that gestational diabetes mellitus in the mother is linked with diabetes, glucose intolerance and obesity in the child through young adulthood.
The fact that vitamin D status may affect a baby’s brain and neurological development is also underscored in the research. In a recent Cochrane Register of Controlled Studies review of research published in the Journal Nutrients, it was confirmed that vitamin D supplementation among mothers during pregnancy “promotes normal skeletal and brain development” among their children.
Multiple sclerosis is also linked to vitamin D deficiency. And research has confirmed that vitamin D deficiency is linked to cognitive decline in adults.
While vitamin D supplementation is certainly an obvious consideration for mothers, there is significant research indicating that supplemental vitamin D may not relieve conditions associated with vitamin D deficiencies.
The body’s ability to produce natural vitamin D should not be ignored. In the Beijing study discussed above, researchers also found that mothers who lived in Beijing had significantly more vitamin D deficiency than those who lived outside the city. This of course correlates with the fact that city dwellers tend to be outside less and thus receive less sunlight exposure.
The researchers stated that, “the study indicates that pregnant women and neonates residing in Beijing are at high risk of vitamin D deficiency.”
Beijing is also known for its smog, which reduces UVB exposure.
Song SJ, Si S, Liu J, Chen X, Zhou L, Jia G, Liu G, Niu Y, Wu J, Zhang W, Zhang J. Vitamin D status in pregnant women and newborns in Beijing and their relationships to birth size. Public Health Nutr. 2012 Jul 16:1-6.
Gernand AD, Simhan HN, Klebanoff MA, Bodnar LM. Maternal Serum 25-Hydroxyvitamin D and Measures of Newborn and Placental Weight in a U.S. Multicenter Cohort Study. J Clin Endocrinol Metab. 2012 Nov 16.
Ioannou C, Javaid MK, Mahon P, Yaqub MK, Harvey NC, Godfrey KM, Noble JA, Cooper C, Papageorghiou AT. The effect of maternal vitamin d concentration on fetal bone. J Clin Endocrinol Metab. 2012 Nov;97(11):E2070-7.
Walsh JM, McGowan CA, Kilbane M, McKenna MJ, McAuliffe FM. The Relationship Between Maternal and Fetal Vitamin D, Insulin Resistance, and Fetal Growth. Reprod Sci. 2012 Sep 11.
Morse NL. Benefits of docosahexaenoic acid, folic acid, vitamin D and iodine on foetal and infant brain development and function following maternal supplementation during pregnancy and lactation. Nutrients. 2012 Jul;4(7):799-840.
Burris HH, Rifas-Shiman SL, Kleinman K, Litonjua AA, Huh SY, Rich-Edwards JW, Camargo CA Jr, Gillman MW. Vitamin D deficiency in pregnancy and gestational diabetes mellitus. Am J Obstet Gynecol. 2012 Sep;207(3):182.e1-8.
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