Table 2 Mean serum vitamin D levels in relation to reproductive history, life–style factors and season

Age (years)

 ≤50

162

84.4 (80.3–88.6)

Ref.

 >50 – ≤55

164

88.6 (84.3–92.8)

0.10

 >55 – ≤60

141

87.7 (83.0–92.5)

0.29

 >60 – ≤65

146

88.5 (84.6–92.5)

0.13

 >65

114

93.6 (88.3–98.9)

0.01

0.107

BMI (kg/m2)

 <20

41

93.2 (83.6–102.8)

0.62

 ≥20 – <25

336

91.0 (88.1–93.9)

Ref.

 ≥25 – <30

259

87.9 (84.6–91.1)

0.16

 ≥30

91

77.3 (71.7–82.9)

<0.001

<0.001

Oral contraception

 No

366

86.9 (84.2–89.5)

Ref.

 Yes

361

89.7 (86.8–92.6)

0.011

0.011

Menopausal status

 Pre

187

85.0 (81.1–88.8)

Ref.

 Peri/Post

540

89.4 (87.1–91.7)

0.056

0.056

MHT** (n = 537)

 No

422

89.2 (86.6–91.8)

Ref.

 Yes

115

90.8 (85.7–95.9)

0.57

0.27

Smoking status

 Never

306

87.9 (85.0–90.8)

Ref.

 Current

201

87.3 (83.3–91.3)

0.813

 Ex

220

89.7 (86.0–93.4)

0.443

0.635

Alcohol consumption

 Zero

57

80.3 (72.8–87.8)

Ref.

 <15 g/day

457

88.9 (86.4–91.4)

0.025

 15 – 30 g/day

100

89.5 (84.8–94.3)

0.032

 >30 g/day

20

82.7 (66.3–99.1)

0.762

 Infrequent

93

89.7 (83.9–95.5)

0.049

0.169

Baseline season

 Spring

199

78.6 (74.8–82.4)

Ref.

 Summer

203

99.0 (95.2–102.7)

<0.001

 Autumn

149

89.6 (85.8–93.5)

<0.001

 Winter

176

85.7 (81.8–89.6)

0.011

<0.001

Education

 O–level college

496

89.3 (86.9–91.7)

Ref.

 A–level college

57

83.4 (75.8–91.0)

0.128

 University

174

87.0 (83.0–91.0)

0.324

0.236

Socio–economic index

 Manual

274

89.0 (85.6–92.5)

Ref.

 Non–manual

396

88.5 (85.9–91.1)

0.796

 Employer

56

83.9 (77.3–90.5)

0.221

0.158

Born in Sweden

 Yes

657

89.3 (87.2–91.4)

Ref.

 No

70

78.6 (72.0 –85.3)

0.002

0.00