Table 4 |
||||||
Biochemical measures for maternal baseline, maternal delivery, and cord blood specimens, by supplementation group | ||||||
Biomarker (units) | Placebo | Vitamin D | Group difference ^{1} | Group-by-time effect^{2} | ||
(n = 80) | (n = 80) | Mean | 95% CI | Mean | 95% CI | |
25(OH)D (nmol/L) | ||||||
Baseline^{3} | 44.0 ± 20.9 | 45.4 ± 18.4 | 1.4 | [−4.8, 7.5] | – | – |
Delivery (n = 130)^{4} | 38.4 ± 18.1 | 134.4 ± 30.7 | 96.0^{***} | [87.6, 104.8] | 94.6^{***} | [85.0, 104.1] |
Cord (n = 132)^{5} | 39.0 ± 18.7 | 102.8 ± 28.6 | 63.9^{***} | [55.8, 72.0] | – | – |
Calcium (mmol/L) | ||||||
Baseline | 2.27 ± 0.09 | 2.25 ± 0.09 | −0.02 | [−0.04, 0.01] | – | – |
Delivery (n = 130) | 2.31 ± 0.11 | 2.32 ± 0.10 | 0.02 | [−0.02, 0.05] | 0.03 | [−0.01, 0.07] |
Albumin-adjusted calcium (mmol/L) | ||||||
Baseline | 2.36 ± 0.07 | 2.35 ± 0.07 | −0.01 | [−0.03, 0.01] | – | – |
Delivery (n = 130) | 2.40 ± 0.08 | 2.43 ± 0.09 | 0.03^{*} | [0.00, 0.06] | 0.04^{*} | [0.01, 0.07] |
PTH (pmol/L)^{6} | ||||||
Baseline | 2.7 (0.3, 9.3) | 2.9 (0.5, 9.4) | 0.02 | [−0.7, -0.2] | – | – |
Delivery (n = 129)^{7} | 3.9 (0.3, 20.5) | 2.3 (0.3, 9.8) | −0.51^{***} | [−0.8, -0.3] | −0.53^{***} | [−0.8, -0.3] |
Urinary calcium-creatinine ratio (mmol/mmol) ^{8} | ||||||
Baseline | 0.24 (0.0, 0.68) | 0.22 (0.0, 0.88) | −0.01 | [−0.07, 0.05] | – | – |
2 weeks (n = 151)^{9} | 0.26 (0.0, 1.11) | 0.26 (0.0, 1.25) | 0.03 | [−0.04, 0.10] | – | – |
Delivery (n = 125)^{10} | 0.13 (0.0, 1.26) | 0.20 (0.0, 2.26) | 0.04 | [−0.05, 0.14] | 0.07 | [−0.03, 0.16] |
^{1} Mean difference [95% CI] between the placebo and vitamin D group at a given time, by ordinary least square estimation.
^{2} Mean difference [95% CI] in the change for vitamin D versus placebo group (difference in the slope) using generalized estimation equations (GEE) to account for within-subject correlations.
^{3} Mean ± standard deviation (SD).
^{4} Delivery specimens were those collected within +/−1 day of delivery; n = 63 and n = 67 in the placebo and vitamin D groups, respectively;
^{5} Cord serum available for n = 67 in the placebo and n = 65 in the vitamin D group.
^{6} Median (range) summarize maternal PTH concentrations, due to right-skewed distributions. PTH concentrations were log-transformed to approximate normality for regression analyses. The results presented as group differences are log-transformed PTH concentrations.
^{7} PTH concentration at delivery available for n = 63 in placebo group and n = 66 in the vitamin D group.
^{8} Median (Range) summarize Ca: Cr ratios in the first two columns. Ca: Cr ratios were square root-transformed to approximate normality for regression analyses; thus, the regression coefficients and confidence bounds are presented on a square-root scale.
^{9} Two-week specimens were defined as those collected 14 +/−1 days after enrolment.
^{10} Delivery urine samples were taken day of delivery, +/−1 day, n = 60 and n = 65 in the placebo and vitamin D groups, respectively.
*p-value < 0.05; **p-value 0.01; ***p-value < 0.001.
Roth et al.
Roth et al. Nutrition Journal 2013 12:47 doi:10.1186/1475-2891-12-47