Randomized placebo-controlled trial of high-dose prenatal third-trimester vitamin D3 supplementation in Bangladesh: the AViDD trial

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 effect²
Biomarker (units)	(n = 80)	(n = 80)	Mean	95% CI	Mean	95% CI
25(OH)D (nmol/L)
Baseline³	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.