Table 1

Baseline comparisons between groups of vitamin D status (deficient/insufficient/sufficient) at 3 months postpartum and between tertiles of PTH at 3 months postpartum

Vitamin D statusPTertiles of PTHP
Deficient 
(25-OH-D <50 nmol/L)Insufficient 
(50 nmol/L ≤ 
25-OH-D < 75 nmol/L)Sufficient 
(25-OH-D ≥75 nmol/L)1st 
(PTH ≤2.6 pmol/L)2nd 
(2.6 pmol/L < PTH ≤ 3.8 pmol/L)3rd 
(PTH >3.8 pmol/L)
n161178155167174153
Months postpartum3 (3–4)3 (3–4)3 (3–4)0.103 (3–4)3 (3–4)3 (3–4)0.05
Age (years)34.5 ± 4.234.9 ± 4.535.0 ± 4.10.4734.8 ± 4.434.8 ± 4.534.6 ± 3.90.88
Ethnicity (%)<0.0010.06
 White60.073.681.971.475.967.3
 Asian14.311.29.014.311.09.1
 Other25.515.29.014.313.223.5
Family history of T2DM (%)57.054.043.20.0447.650.356.90.25
Current smoking (%)8.13.31.30.0083.04.65.20.58
Season of blood sample collection (%)0.470.19
 Winter27.920.220.718.425.924.2
 Spring 27.928.023.923.227.629.4
 Summer17.421.323.927.418.417.0
 Fall26.730.331.630.128.229.4
Total physical activity4.7 ± 1.05.0 ± 1.05.1 ± 1.00.0015.0 ± 0.95.0 ± 1.14.8 ± 1.00.06
 Sport index1.8 (1.5–2.3)2.0 (1.5–2.5)2.0 (1.8–2.5)0.032.0 (1.5–2.5)2.0 (1.5–2.5)1.8 (1.5–2.6)0.32
 Leisure-time index2.8 (2.5–3.3)3.0 (2.5–3.3)3.0 (2.5–3.5)0.0023.0 (2.8–3.5)3.0 (2.5–3.2)2.8 (2.5–3.3)0.03
Duration of breast-feeding (months)3.0 (2.0–4.0)3.0 (2.5–3.0)3.0 (3.0–3.5)0.303.0 (3.0–3.0)3.0 (3.0–4.0)3.0 (2.0–4.0)0.75
25-OH-D (nmol/L)35.7 ± 10.264.4 ± 7.491.9 ± 12.5<0.00172.6 ± 21.864.1 ± 24.150.1 ± 23.3<0.001
PTH (pmol/L)4.0 (3.2–4.8)2.9 (2.2–3.7)2.7 (2.1–3.5)<0.0012.1 (1.8–2.4)3.2 (2.9–3.5)4.8 (4.3–5.6)<0.001
BMI (kg/m2)27.8 (23.9–32.3)25.3 (23.4–28.9)24.5 (22.1–27.6)<0.00124.5 (22.3–27.6)26.0 (23.2–29.2)27.6 (24.1–32.1)<0.001
Waist circumference (cm)90.0 (83–100)88.0 (82–96)86.0 (81–93)0.0385.5 (80–92)88.5 (81–97)91.0 (83–100)<0.001
Matsuda index7.7 (5.0–11.6)11.6 (7.8–15.5)14.0 (9.0–17.6)<0.00112.2 (8.4–16.6)11.1 (6.9–15.8)8.8 (5.8–12.9)<0.001
ISSI-2706 (543–933)733 (625–994)797 (602–1,045)0.04810 (622–1,009)721 (581–958)741 (565–955)0.06
Fasting glucose on OGTT (mmol/L)4.7 ± 0.64.6 ± 0.44.5 ± 0.4<0.0014.5 ± 0.44.6 ± 0.54.7 ± 0.50.004
2-h glucose on OGTT (mmol/L)6.3 (5.3–7.5)6.0 (5.1–7.3)5.7 (4.8–6.7)0.0025.8 (5.1–7.0)6.1 (5.2–7.4)6.0 (4.9–7.2)0.16
  • Continuous data are presented as mean ± SD (if normally distributed) or median (25th–75th) if skewed.