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Table 2 Odds of vitamin D deficiency early in pregnancy (n = 204)

From: Vitamin D status and its determinants in healthy pregnant women living in Switzerland in the first trimester of pregnancy

 

Univariable models

Multivariable model 1g

Multivariable model 2h

Multivariable model 3i

OR

95% CI

OR

95% CI

OR

95% CI

OR

95% CI

Age

0.93

0.87–0.99

0.98

0.90–1.06

–

–

–

–

Week of pregnancy

1.04

0.87–1.25

0.86

0.68–1.08

–

–

–

–

Nulliparitya

1.26

0.70–2.28

–

–

–

–

–

–

First pregnancyb

1.23

0.68–2.24

1.16

0.49–2.75

–

–

–

–

BMI before pregnancy

1.10

1.01–1.20

–

–

–

–

–

–

BMI current

1.10

1.02–1.21

1.08

0.98–1.20

1.08

0.99–1.19

–

–

Melanin index

 Melanin index as a continuous variable

1.04

1.00–1.08

–

–

–

–

–

–

 Melanin index Group 1c

1.14

0.56–2.34

–

–

–

–

–

–

 Melanin index Group 2c

1.00

(ref)

–

–

–

–

–

–

 Melanin index Group 3c

2.01

0.96–4.27

–

–

–

–

–

–

Skin colour

 Light

1

(ref)

–

–

–

–

–

–

 Dark

3.92

1.84–9.16

–

–

–

–

–

–

Country of origind

 Group 1

1

(ref)

1

(ref)

1

(ref)

1

(ref)

 Group 2

2.56

1.17–5.79

2.29

0.88–6.16

2.57

1.1–6.2

2.32

1.07–5.17

 Group 3

1.45

0.54–3.92

1.07

0.32–3.51

1.57

0.55–4.54

1.85

0.69–5.06

 Group 4

12.94

3.77–60.91

11.71

2.62–67.84

14.57

3.84–73.97

13.35

3.8–64.68

 Group 5

15.75

4.65–73.58

9.38

2.12–54.11

14.48

3.93–71.71

17.89

5.24–84.42

Education e

 Level 1

1

(ref)

1

(ref)

–

–

–

–

 Level 2

0.31

0.10–0.80

0.64

0.17–2.26

–

–

–

–

 Level 3

0.26

0.09–0.64

0.63

0.15–2.48

–

–

–

–

Education of the partnere

 Level 1

1

(ref)

–

–

–

–

–

–

 Level 2

0.55

0.19–1.47

–

–

–

–

–

–

 Level 3

0.24

0.08–0.62

–

–

–

–

–

–

Smoking status

 Never

1

(ref)

1

(ref)

1

(ref)

–

–

 Ever

0.34

0.18–0.67

0.40

0.17–0.91

0.49

0.23–1.04

–

–

 Current

0.86

0.31–2.64

1.88

0.64–7.23

2.65

0.88–8.91

–

–

Season

 Winter

1

(ref)

1

(ref)

–

–

–

–

 Spring

1.36

0.57–3.35

1.23

0.42–3.65

–

–

–

–

 Summer

0.57

0.26–1.24

0.51

0.20–1.31

–

–

–

–

 Fall

0.93

0.41–2.13

0.88

0.32–2.42

–

–

–

–

Days per week spent at least 1 h outdoor in the past 6 months

1.07

0.95–1.20

0.95

0.81–1.11

–

–

–

–

Using sun protection in summer

 Never

1

(ref)

1

(ref)

–

–

–

–

 Sometimes

0.27

0.11–0.61

0.51

0.17–1.47

–

–

–

–

 Always

0.42

0.17–0.95

0.65

0.2–2.01

–

–

–

–

Fish consumption at least once a week

0.57

0.27–1.13

0.69

0.28–1.65

–

–

–

–

Vitamin D supplement intakef

0.44

0.24–0.80

0.30

0.14–0.63

0.33

0.16–0.65

0.37

0.19–0.71

Comparison of linear regression models: Goodness of fit and best prediction power assessments

 AIC

  

253.19

 

216.14

 

220.09

 

 c-index (95% CI)

  

0.821

(0.761–0.881)

0.796

(0.731–0.860)

0.765

(0.698–0.832)

  1. anon nulliparous
  2. bnot the first pregnancy
  3. cMelanin index: Group 1 = values between 16.6–31.9; Group 2 = values between 31.9–37.1; Group 3 = values between 37.1–68.00
  4. dGroup 1 = Switzerland and Germany; Group 2 = North America, Northern Europe, Caucasus, Central Asia and New Zealand (excluding Switzerland and Germany); Group 3 = Southern Europe, Australia, Latin America and the Caribbean; Group 4 = South East Asia Pacific; Group 5 = Africa and Middle East
  5. eLevel 1 = Less than compulsory education and Compulsory education; Level 2 = Secondary education; Level 3 = Tertiary education
  6. fAll types of supplements containing vitamin D (multivitamin included)
  7. gModel 1: Full model - selection of categorical variables according to Cramer’s V correlation analysis. Selection of continuous variables according to Pearson’s correlation coefficient
  8. hModel 2: model selected using AIC-based forward backward selection
  9. iModel 3: Parsimonious model
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BMC Pregnancy and Childbirth

ISSN: 1471-2393

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