Table 3.
Growth and Bone Parameters in Sex‐Specific Tertiles of CXM in 12‐Month‐Old Infants According to Vitamin D Intervention Group
| Lowest (first tertile) | Intermediate (second tertile) | Highest (third tertile) | p Value | |
|---|---|---|---|---|
| Mean (95% CI) | ||||
| Group‐10 | ||||
| n | 38 | 40 | 27 | |
| Length (SDS) | −0.73 (−1.03, −0.43) | −0.45 (−0.76, −0.13) | −0.34 (−0.85, 0.16) | 0.28 |
| Length (cm) | 75.0 (74.3, 75.8) | 75.3 (74.5, 76.2) | 75.7 (74.4, 76.9) | 0.65 |
| Growth rate in length (SD unit) | −0.15 (−0.46, 0.15) | 0.18 (−0.10, 0.46) | 0.34 (0.04, 0.65) | 0.062 |
| Length velocity (cm/yr) | 24.5 (23.7, 25.4) | 25.1 (24.3, 25.9) | 25.7 (24.6, 26.8) | 0.22 |
| Tibial length (mm) | 138 (136, 140) | 137 (135, 139) | 138 (135, 141) | 0.77 |
| BMC (mg/mm) | 35.1 (32.6, 37.6) | 35.6 (33.3, 37.8) | 36.7 (33.6, 39.8) | 0.70 |
| vBMD (mg/cm3) | 298 (269, 327) | 309 (282, 336) | 309 (278, 340) | 0.81 |
| CSA (mm2)a | 124 (113, 136) | 121 (110, 132) | 124 (111, 138) | 0.89 |
| PMI (mm4)a | 2737 (2169, 3306) | 2541 (1994, 3089) | 2746 (2080, 3411) | 0.85 |
| PsC (mm) a | 39.1 (37.4, 40.9) | 38.7 (37.0, 40.4) | 39.2 (37.0, 41.2) | 0.91 |
| PTH (pg/mL) | 26.9 (21.3, 32.6) | 27.3 (22.9, 31.7) | 31.2 (26.6, 35.8) | 0.14 |
| iCa (mmol/L) | 1.33 (1.33, 1.34) | 1.33 (1.32, 1.34) | 1.33 (1.32, 1.34) | 0.88 |
| 25(OH)D (nmol/L) | 82.4 (76.3, 88.6) | 81.3 (75.3, 87.3) | 79.2 (71.7, 86.7) | 0.79 |
| Group‐30 | ||||
| n | 48 | 46 | 57 | |
| Length (SDS) | −0.85 (−1.10, −0.60) | −1.00 (−1.30, −0.69) | −0.37 (−0.64, −0.10) | 0.003 b |
| Length (cm) e | 74.4 (73.7, 75.1) | 74.1 (73.3, 74.8) | 75.5 (74.8, 76.1) | 0.012 c |
| Growth rate in length (SD unit) | −0.15 (−0.40, 0.10) | −0.33 (−0.71, 0.05) | 0.16 (−0.07, 0.40) | 0.044 d |
| Length velocity (cm/yr) | 24.1 (23.4, 24.7) | 23.7 (23.0, 24.5) | 25.2 (24.5, 25.8) | 0.008 e |
| Tibial length (mm) | 136 (134, 138) | 136 (134, 138) | 138 (136, 140) | 0.24 |
| BMC (mg/mm) | 34.4 (32.2, 36.6) | 35.0 (32.4, 37.6) | 37.0 (35.0, 39.1) | 0.20 |
| vBMD (mg/cm3) | 306 (283, 328) | 306 (286, 325) | 293 (276, 310) | 0.54 |
| CSA (mm2)a | 117 (107, 126) | 120 (110, 130) | 132 (123, 141) | 0.067 |
| PMI (mm4)a | 2370 (1899, 2841) | 2549 (2069, 3030) | 2997 (2560, 3435) | 0.14 |
| PsC (mm) a | 38.0 (36.6, 40.4) | 38.5 (37.0, 40.0) | 40.3 (39.0, 41.7) | 0.054 |
| PTH (pg/mL) | 20.6 (16.9, 24.3) | 29.2 (23.3, 35.1) | 24.3 (19.8, 28.8) | 0.048 f |
| iCa (mmol/L) | 1.34 (1.33, 1.35) | 1.34 (1.33, 1.35) | 1.33 (1.32, 1.34) | 0.66 |
| 25(OH)D (nmol/L) | 122.0 (112.8, 131.3) | 114.7 (107.1, 122.4) | 117.2 (110.1, 124.3) | 0.44 |
CXM = collagen X biomarker; CI = confidence interval; group‐10 = vitamin D intervention group receiving 10 μg/d; group‐30 = vitamin D intervention group receiving 30 μg/d; SDS = standard deviation score (based on Finnish sex‐ and age‐specific normative data of child size); BMC = total bone mineral content; vBMD = total volumetric bone mineral density; CSA = total cross‐sectional area; PMI = total polar moment of inertia; PsC = periosteal circumference; PTH = parathyroid hormone; iCa = ionized calcium; 25(OH)D = 25‐hydroxy‐vitamin D.
Statistical significance between tertiles analyzed using ANOVA and ANCOVA.
CXM tertiles in girls: lowest, 3.45–31.17 ng/mL; intermediate, 31.97–40.85 ng/mL; highest, 40.99–91.99 ng/mL; and in boys: lowest, 1.59–32.81 ng/mL; intermediate, 32.82–43.22 ng/mL; highest, 43.37–136.62 ng/mL.
Two values missing for tibial length; one BMC outlier excluded; and five values missing for 25(OH)D.
Adjusted for the tibial length (mm) at 12 months.
Significance between first and third tertile (mean difference [95% CI] –0.48 [−0.95, −0.02], p = 0.039) and between second and third tertile (mean difference [95% CI] –0.63 [−1.10, −0.16], p = 0.004).
Significance between second and third tertile (mean difference [95% CI] –1.42 [−2.60, −0.23], p = 0.014).
Significance between second and third tertile (mean difference [95% CI] –0.50 [−0.98, −0.01], p = 0.044).
Significance between second and third tertile (mean difference [95% CI] –1.43 [−2.58, −0.27], p = 0.010); sex‐interaction (MANOVA, p < 0.001); significant differences observed in girls in group‐30 (p = 0.008) and not in group‐10 (p = 0.83) and no differences in boys in either intervention groups (p > 0.12).
Significance between first and second tertile (mean difference in logarithmic scale [95% CI] –0.15 [−0.30, −0.00], p = 0.043).