TABLE 2.

Comparison of pregnant women's serum total 25(OH)D, 25(OH)D₂, 25(OH)D₃, and 3-epi-25(OH)D₃ concentrations across trimesters of pregnancy¹

	First trimester (9.9–14.7 wk)	Second trimester (20.7–25.3 wk)	Third trimester (31.6–34.6 wk)	P value
25(OH)D2,2 nmol/L	1.8 ± 0.9b	2.2 ± 1.4a	2.9 ± 2.2a	<0.0001
25(OH)D3, nmol/L	65.7 ± 20.6b	84.3 ± 30.9a	85.3 ± 28.9a	<0.0001
Total 25(OH)D, nmol/L	67.5 ± 20.4b	86.5 ± 30.9a	88.3 ± 29.0a	<0.0001
3-epi-25(OH)D3,3 nmol/L	3.0 ± 1.7	3.1 ± 2.4	3.8 ± 2.2	0.57

¹Values are means ± SDs, n = 79.

²25(OH)D₂ concentrations were under the detection limit of 3 nmol/L for 70, 60, and 44 participants in the first, second, and third trimesters, respectively. In those cases, a value of 1.5 nmol/L was used.

³3-epi-25(OH)D₃ concentrations were under the detection limit of 2.5 nmol/L for 31, 34, and 40 participants in the first, second, and third trimesters, respectively. In those cases, a value of 1.25 nmol/L was used. All P values refer to repeated-measures ANOVA adjusted for season at the time of sampling, prepregnancy BMI, and vitamin D intake from supplements. Labeled means in a row without a common letter differ, P < 0.05. 3-epi-25(OH)D₃, 3-epi-25-hydroxyvitamin D₃; 25(OH)D, 25-hydroxyvitamin D; 25(OH)D₂, 25-hydroxyergocalciferol; 25(OH)D₃, 25-hydroxycholecalciferol.