Relationship Observed Between Cord Blood Vitamin D and Child's Adiponectin Levels

Norra MacReady

October 31, 2010

October 31, 2010 (San Diego, California) — Higher cord blood levels of 25-hydroxyvitamin D [25(OH)D] show an association with higher adiponectin levels in children at age 3 years, Susanna Y. Huh, MD, MPH, reported here at Obesity 2010: The Obesity Society 28th Annual Scientific Meeting.

Each 25 nmol/L increment in cord blood 25(OH)D also was associated with a decrement of 0.15 in the child's body mass index (BMI) z-score at age 3 years, but the association became null after further adjustment for maternal BMI, according to Dr. Huh, from Children's Hospital Boston and instructor of pediatrics at Harvard Medical School in Boston, Massachusetts.

Dr. Huh and colleagues found no association between cord blood vitamin D levels and any of the other parameters measured, including skinfold thickness, blood pressure, and leptin levels at age 3 years.

One important finding that emerged from this study is that "it's pretty clear that pregnant women are not getting enough vitamin D," Dr. Huh told Medscape Medical News. She noted that the American Academy of Pediatrics recommends that children receive 400 IU vitamin D daily to ensure adequate blood levels.

An inverse association has been observed between serum adiponectin levels and body fat stores in adults, Dr. Huh explained. The exact metabolic relationship between vitamin D and obesity is unclear, but in animal studies, it appears to influence the function of pancreatic cells and endothelial cells lining the blood vessels. "There's actually a host of potential mechanisms by which it might affect obesity and related conditions."

Vitamin D deficiency is common in pregnancy and has been associated with other conditions, she added. "That, along with the animal data, is what prompted us to look at this association."

"To some extent, our findings were surprising because we know that at older ages, it is well-established that adiponectin is related to obesity, but that relationship has not been studied that extensively in the preschool years. So from that standpoint, it is definitely possible that this relationship could exist in the absence of a relationship between vitamin D and obesity," she told Medscape Medical News.

Dr. Huh and colleagues measured 25(OH)D levels in maternal blood during the second trimester (n = 990) and in cord blood at delivery (n = 629) among women participating in Project Viva, a longitudinal research study of women and children designed to examine the effect of maternal diet and other health factors on the health of both mother and child. They then examined the associations, if any, between maternal and cord blood vitamin D levels between the child's BMI z-score (a measure of how far the parameter deviates from the mean, expressed in terms of the standard deviation), central and overall adiposity (as measured by the ratio and sum, respectively, of subscapular and triceps skinfold thickness), plasma leptin and adiponectin, and systolic blood pressure at age 3 years.

Of all of these measures, the only association seen was between cord blood 25(OH)D and subsequent adiponectin levels (β 1.4 mcg/mL; 95% confidence interval, 0.29 - 2.56) after adjustment for covariates including maternal BMI, said Dr. Huh. No relationship was seen between maternal 25(OH)D levels in the second trimester and any of the child outcomes in the multivariate model.

It is still premature to speculate on the clinical implications of these findings, she noted. "What we can say is that vitamin D deficiency was fairly common among the women we studied: 40% of the babies had blood levels less than 15 nmol/L, and an additional 21% had levels between 50 and less than 75 nmol/L. Many vitamin D experts consider a level less than 75 nmol/L to be insufficient. So one implication of our findings is that if lower vitamin D levels at birth are associated with lower adiponectin levels at age 3 [years], then pregnant women probably should be taking more vitamin D to protect against that."

Dr. Huh has disclosed no relevant financial relationships.

Obesity 2010: The Obesity Society 28th Annual Scientific Meeting: Abstract 78-OR. Presented October 12, 2010.

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