A novel inverse association between cord 25-hydroxyvitamin D and leg length in boys up to three years. An Odense Child Cohort study

作者：Christensen Mathilde Egelund; Beck Nielsen Signe Sparre; Dalgard Christine; Larsen Sos Drag**aek; Lykkedegn Sine; Kyhl Henriette Boye; Hu**y Steffen; Christesen Henrik Thybo^*

来源：PLos One, 2018, 13(6): e0198724.

DOI：10.1371/journal.pone.0198724

Background and aim
Long standing vitamin D deficiency in children causes rickets with growth impairment. We investigated whether sub-ischial leg length (SLL) is shorter, and cephalo-caudal length: length (CCL:L) ratio and sitting height:height (SH:H) ratio larger, with lower cord s-25-hydroxyvitamin D (250HD) in the population-based prospective Odense Child Cohort, Denmark.
Methods
We included healthy singletons born to term with available measures of cord 250HD and anthropometrics up to three years' age. Linear regression was stratified by sex a priori and adjusted for maternal ethnicity, pre-pregnancy body mass index and smoking during pregnancy, season of blood sampling and child age.
Results
Median (IQR) cord 250HD was 48.0 (34.0-62.4) nmol/L. At mean age 19.1 months, n = 504, mean (SD) SLL was 31.7 (1.7) cm; CCL:L-ratio 0.62 (0.01). At 36.3 months, n = 956, mean SLL was 42.9 (2.0) cm; SH:H-ratio 0.56 (0.01). No participants had rickets. In adjusted analyses, 19-months-old boys had 0.1 cm shorter SLL (p = 0.009) and 0.1% higher CCL:Lratio (p = 0.04) with every 10 nmol/L increase in cord 250HD. Similar findings were seen for late pregnancy 250HD. In the highest cord 250HD quartile (>60.7 nmol/L), SLL was 0.8 cm shorter (95% C.I.: 1.36;-0.29, linear trend, p = 0.004), and CCL:L-ratio 0.8% higher (95% C.I. 8.0x10(-05) ;0.01, linear trend, p = 0.01), compared to lowest quartile (<30.7 nmol/L). Similar associations with cord 250HD were observed in 3-year-old boys. No consistent associations between 250HD and anthropometrics were seen in girls at either age.
Conclusion
No leg shortening was found with decreasing cord s-250HD in a healthy population of infants. A small, yet significant inverse association between cord 250HD and SLL in boys 11/2-3 years warrants further investigations.