Associations of maternal and fetal 25-hydroxyvitamin D levels with
childhood lung function and asthma. The Generation R Study.
Supplementary material
Table E-1
Observed and imputed characteristics of mothers and their children
Table E-2
Characteristics of subjects included and lost to follow-up
Table E-3
Associations of 25-hydroxyvitamin D levels with Rint and FeNO in children at
age 6 years: unadjusted model
Table E-4
Associations of 25-hydroxyvitamin D levels with wheezing patterns and
asthma of children until age 6 years: unadjusted model
Table E-5
Associations of 25-hydroxyvitamin D levels with Rint and FeNO, additionally
adjusted for child’s 25-hydroxyvitamin D level
Table E-6
Associations of 25-hydroxyvitamin D levels with wheezing patterns and
asthma, additionally adjusted for child’s 25-hydroxyvitamin D level
Table E-7
Associations of 25-hydroxyvitamin D levels with Rint and FeNO in children at
age 6 years according to clinical cut-offs of 25-hydroxyvitamin D
Table E-8
Associations of 25-hydroxyvitamin D levels with wheezing patterns and
asthma of children until age 6 years according to clinical cut-offs of 25hydroxyvitamin D
Figure E-1
Flowchart of participants
Table E-1. Observed and imputed characteristics of mothers and their children
Maternal characteristics
Age, years
Missing
Body mass index at enrolment
Missing
Educational level (%)
Primary, or secondary
Higher
Missing
History of asthma or atopy (%)
No
Yes
Missing
Psychological distress
Missing
Parity (%)
0
≥1
Missing
Smoking during pregnancy (%)
No
Yes
Missing
Pet keeping (%)
No
Yes
Missing
Folate level in 1st trimester, nmol/L
Missing
Mid-gestational blood sampling season (%)
Spring
Summer
Autumn
Winter
Missing
Child characteristics
Female sex (%)
Missing
Gestational age at birth (weeks)
Missing
Birth weight (grams)
Missing
Ever breastfeeding (%)
No
Yes
Missing
Observed
Imputed
31.6 (4.2)
0
24.2 (4.0)
0.5 (16)
Not imputed
38.5 (1,159)
61.5 (1,924)
1.5 (47)
37.8 (1,184)
62.2 (1,946)
62.3 (1,762)
37.7 (1,066)
9.6 (302)
0.2 (0.2)
11.3 (353)
63.5 (1,987)
36.5 (1,143)
60.7 (1,901)
39.3 (1,229)
0
Not imputed
88.0 (2,183)
22.0 (688)
8.3 (259)
86.0 (2,380)
24.0 (750)
61.9 (1,612)
38.1 (1,192)
10.4 (326)
20.2 (8.7)
22.2 (694)
57.8 (1,809)
42.2 (1,321)
28.5 (817)
23.2 (665)
24.0 (688)
24.2 (693)
8.5 (267)
28.9 (906)
23.1 (724)
23.8 (744)
24.1 (755)
50.3 (1,573)
0
40.0 (26.7-43.4)
0
3,503 (547)
0.1 (4)
Not imputed
8.5 (249)
91.5 (2,112)
24.6 (769)
9.1 (315)
89.9 (2,815)
24.2
0.2
20.2
Not imputed
3,503
Lower respiratory infections (%)
No
95.9 (2,769)
95.9 (2,999)
Yes
4.1 (119)
4.1 (131)
Missing
7.7 (242)
Inhalant allergies (%)
No
91.2 (2,598)
91.2 (2,853)
Yes
8.8 (250)
8.8 (277)
Missing
9.0 (282)
Eczema (%)
No
84.0 (2,164)
83.6 (2,617)
Yes
16.0 (413)
16.4 (513)
Missing
17.7 (533)
At birth blood sampling season (%)
Spring
25.0 (715)
Not imputed
Summer
25.9 (741)
Autumn
28.4 (811)
Winter
20.7 (591)
Missing
0
Values are means (SD), medians (total range) or percentages (absolute numbers)
Table E-2. Characteristics of subjects included and lost to follow-up
Maternal characteristics
Age, years
Body mass index at enrolment
Educational level (%)
Primary, or secondary
Higher
History of asthma or atopy, yes (%)
No
Yes
Psychological distress
Parity (%)
0
≥1
Smoking during pregnancy (%)
No
Yes
Pet keeping (%)
No
Yes
Folate level in 1st trimester, nmol/L
Mid-gestational blood sampling season (%)
Spring
Summer
Autumn
Winter
Child characteristics
Female sex (%)
Gestational age at birth (weeks)
Birth weight (grams)
Ever breastfeeding (%)
No
Yes
Lower respiratory infections (%)
No
Yes
Inhalant allergies (%)
No
Yes
Eczema (%)
No
Yes
At birth blood sampling season (%)
Spring
Included
N= 3,130
Lost to follow-up
n = 297
p-value for
difference
31.6 (4.2)
24.2 (4.0)
29.4 (5.4)
25.2 (4.8)
0.001
0.009
61.5 (1,924)
38.5 (1,159)
87.0 (254)
13.0 (38)
0.001
62.3 (1,762)
37.7 (1,066)
0.2 (0.2)
66.3 (185)
33.7 (94)
0.2 (0.3)
0.195
60.7 (1,901)
39.3 (1,229)
52.5 (156)
42.8 (127)
88.0 (2,183)
22.0 (688)
55.1 (156)
44.9 (127)
0.001
61.9 (1,612)
38.1 (1,192)
20.2 (8.7)
35.4 (105)
57.2 (170)
17.1 (8.9)
0.001
28.5 (817)
23.2 (665)
24.0 (688)
24.2 (693)
27.9 (83)
24.2 (72)
16.5 (49)
18.2 (54)
0.076
50.3 (1,573))
40.0 (26.7, 43.4)
3,503 (547)
43.4 (129)
39.6 (26.7-42.8)
3,383 (585)
0.025
0.002
0.001
8.5 (249)
91.5 (2,112)
24.3 (37)
75.7 (115)
0.001
95.9 (2,769)
4.1 (119)
94.3 (66)
5.7 (4)
0.535
91.2 (2,598)
8.8 (250)
91.7 (66)
8.3 (6)
0.554
84.0 (2,164)
16.0 (413)
83.3 (5)
16.7 (1)
1.000
25.0 (715)
24.3 (157)
0.441
0.028
0.006
0.001
Summer
25.9 (741)
27.7 (179)
Autumn
28.4 (811)
22.9 (148)
Winter
20.7 (591)
25.2 (163)
Values are means (± SD), medians (total ranges) or percentages (absolute numbers) based
on original data. P-value for difference was calculated using Student’s t-test for continuous
normally distributed variables, Mann-Whitney U test for continuous not normally distributed
variables, and chi-square test for categorical variables.
Table E-3. Associations of 25-hydroxyvitamin D levels with Rint and FeNO in children at age
6 years: unadjusted model (n= 3,130)
Rint
FeNO
Z-score
Symmpercent
(95% CI)
(95% CI)
n = 1,929
n = 1,857
0.18 (-0.13, 0.49)
-3.7 (-9.9, 2.5)
597/1,752
612/1,706
2nd tertile, n = 1,081
-0.13 (-0.44, 0.18)
0.3 (-6.1, 6.7)
52.5 – 80.7 nmol/L
584/1,752
549/1,706
3rd tertile, n = 1,079
Reference
Reference
80.9 – 193.2 nmol/L
571/1,752
551/1,706
0.89
0.40
1st tertile, n = 813
-0.33 (-0.66, 0.01)
-0.2 (-7.4, 7.0)
0.1 – 30.5 nmol/L
449/1,326
439/1,238
2nd tertile, n = 793
0.16 (-0.18, 0.50)
1.7 (-5.7, 9.1)
30.6 – 49.0 nmol/L
415/1,326
389/1,238
3rd tertile, n = 801
Reference
Reference
49.2- 144.9 nmol/L
462/1,326
410/1,238
0.05
0.56
25-hydroxy vitamin D in mid-gestation
1st tertile, n = 1,083
2.3 – 52.4 nmol/L
p-value for trend
25-hydroxy vitamin D at birth
p-value for trend
Values are changes in Z-score or sympercent (95% confidence interval) from linear regression
models. “n =” represents number of cases per total group.
Table E-4. Associations of 25-hydroxyvitamin D levels with wheezing patterns and asthma of children until age 6 years: unadjusted model
(n=3,130)
Early Wheezing
Late Wheezing
Persistent Wheezing
Asthma
Odds Ratio
Odds Ratio
Odds Ratio
Odds Ratio
(95% CI)
(95% CI)
(95% CI)
(95% CI)
n = 604
n = 77
n = 255
n = 158
1.33 (1.03, 1.31)*
1.13 (0.63, 2.02)
0.98 (0.69, 1.38)
1.03 (0.69, 1.53)
192/657
24/657
72/657
51/782
2nd tertile, n = 1,081
1.45 (1.13, 1.86)*
1.09 (0.61, 1.97)
1.13 (0.81, 1.58)
0.88 (0.58, 1.32)
52.5 – 80.7 nmol/L
207/676
23/676
82/676
45/800
3rd tertile, n = 1,079
Reference
Reference
Reference
Reference
80.9 – 193.2 nmol/L
163/686
24/686
83/686
51/801
0.01
0.43
0.91
0.90
1st tertile, n = 813
1.05 (0.78, 1.40)
1.08 (0.58, 2.02)
0.96 (0.65, 1.42)
0.91 (0.57, 1.44)
0.1 – 30.5 nmol/L
130/492
21/492
59/492
37/591
2nd tertile, n = 793
1.11 (0.84, 1.48)
0.59 (0.29, 1.22)
0.88 (0.59, 1.30)
0.87 (0.55, 1.39)
30.6 – 49.0 nmol/L
144/506
12/506
56/506
36/597
Reference
Reference
Reference
Reference
134/525
21/525
66/525
41/599
25-hydroxy vitamin D in mid-gestation
1st tertile, n = 1,083
2.3 – 52.4 nmol/L
p-value for trend
25-hydroxy vitamin D at birth
3rd tertile, n = 801
49.2- 144.9 nmol/L
p-value for trend
0.70
0.44
0.84
0.88
*P<0.05; Values are odds ratios (95% confidence interval) from polynomial regression and logistic regression models. “n =” represents number
of cases per total group.
Table E-5. Associations of 25-hydroxyvitamin D levels with Rint and FeNO in children at age 6 years
additionally adjusted for child’s 25-hydroxyvitamin D level (n = 1,783)
Rint
FeNO
Z-score
Symmpercent
(95% CI)
(95% CI)
n = 1,248
n = 1,227
1st tertile, n = 576
0.47 (-0.04, 0.97)
-0.9 (-10.7, 8.8)
2.3 – 52.4 nmol/L
401/1,142
413/1,129
2nd tertile, n = 549
-0.05 (-0.54, 0.43)
-2.6 (-12.0, 6.8)
52.5 – 80.7 nmol/L
375/1,142
361/1,129
3rd tertile, n = 520
Reference
Reference
80.9 – 193.2 nmol/L
366/1,142
355/1,129
0.20
0.55
1st tertile, n = 416
-0.55 (-1.08, 0.01)
-3.7 (-14.0, 6.6)
0.1 – 30.5 nmol/L
282/849
281/824
2nd tertile, n = 395
0.21 (-0.28, 0.70)
7.0 (-2.4, 16.4)
30.6 – 49.0 nmol/L
277/849
263/824
Reference
Reference
290/849
280/824
0.32
0.93
25-hydroxy vitamin D in mid-gestation
p-value for trend
25-hydroxy vitamin D at birth
3rd tertile, n = 402
49.2- 144.9 nmol/L
p-value for trend
Values are changes in Z-score or sympercent (95% confidence interval) from linear regression
models. “n =” represents number of cases per total group. Models were adjusted for maternal
age, body mass index at enrolment, educational level, history of asthma/allergy, maternal
distress, parity, smoking during pregnancy, pet keeping, folate level, mid-gestational season of
blood sampling, child’s sex, gestational age at birth, birth weight, breastfeeding, child’s lower
respiratory tract infections, inhalant allergies, eczema, at birth season of blood sampling, mutually
for mid-gestational and cord blood 25-hydroxyvitamin D and child’s current 25-hydroxy vitamin D.
Table E-6. Associations of 25-hydroxyvitamin D levels with wheezing patterns and asthma of children until age 6 years additionally adjusted for
child’s 25-hydroxyvitamin D level (n = 1,783)
Early Wheezing
Late Wheezing
Persistent Wheezing
Asthma
Odds Ratio
Odds Ratio
Odds Ratio
Odds Ratio
(95% CI)
(95% CI)
(95% CI)
(95% CI)
n = 346
n = 49
n = 135
n = 86
1st tertile, n = 576
1.15 (0.70, 1.90)
0.78 (0.24, 2.49)
0.78 (0.35, 1.73)
1.11 (0.45, 2.76)
2.3 – 52.4 nmol/L
117/403
19/403
38/403
24/468
2 tertile, n = 549
1.28 (0.81, 2.00)
0.91 (0.31, 2.66)
1.55 (0.79, 3.06)
1.64 (0.73, 3.70)
52.5 – 80.7 nmol/L
125/396
13/396
50/396
30/478
Reference
Reference
Reference
Reference
88/367
15/367
40/367
26/438
0.51
0.82
0.57
0.65
1st tertile, n = 416
0.80 (0.46, 1.40)
1.61 (0.47, 5.53)
1.33 (0.57, 3.11)
1.45 (0.60, 3.50)
0.1 – 30.5 nmol/L
68/278
13/278
33/278
22/339
2 tertile, n = 395
1.01 (0.64, 1.59)
1.18 (0.39, 3.56)
1.05 (0.51, 2.18)
1.18 (0.52, 2.69)
30.6 – 49.0 nmol/L
80/279
9/279
25/279
17/337
Reference
Reference
Reference
Reference
80/298
15/298
32/298
20/338
0.58
0.14
0.77
0.35
25-hydroxy vitamin D in mid-gestation
nd
3rd tertile, n = 520
80.9 – 193.2 nmol/L
p-value for trend
25-hydroxy vitamin D at birth
nd
3rd tertile, n = 402
49.2- 144.9 nmol/L
p-value for trend
Values are odds ratios (95% confidence interval) from multivariate polynomial regression and logistic regression models. “n =” represents
number of cases per total group. Models were adjusted for maternal age, body mass index at enrolment, educational level, history of
asthma/allergy, maternal distress, parity, smoking during pregnancy, pet keeping, folate level, mid-gestational season of blood sampling, child’s
sex, gestational age at birth, birth weight, breastfeeding, child’s lower respiratory tract infections, inhalant allergies, eczema, at birth season of
blood sampling, mutually for mid-gestational and cord blood 25-hydroxyvitamin D and child’s current 25-hydroxy vitamin D.
Table E-7. Associations of 25-hydroxyvitamin D levels with Rint and FeNO in children at age 6
years according to clinical cut-offs of 25-hydroxyvitamin D (n = 3,130)
Rint
FeNO
Z-score
Symmpercent
(95% CI)
(95% CI)
n = 1,929
n = 1,857
0.20 (-0.15, 0.54)
-2.2 (-9.1, 4.6)
528/1,754
541/1,707
-0.15 (-0.49, 0.18)
-2.0 (-8.8, 4.7)
50-74.9 nmol/L
547/1,754
509/1,707
Optimal n = 1,138
Reference
Reference
≥75.0 nmol/L
679/1,754
657/1,707
0.75
0.27
-0.27 (-0.63, 0.08)
-0.4 (-8.1, 7.3)
893/1,332
846/1,241
0.17 (-0.21, 0.55)
3.9 (-4.3, 12.1)
50-74.9 nmol/L
354/1,332
319/1,241
Optimal n = 150
Reference
Reference
94/1,332
76/1,241
0.03
0.77
25-hydroxy vitamin D in mid-gestation
Deficient, n = 856
<50.0 nmol/L
Sufficient n = 867
p-value for trend
25-hydroxy vitamin D at birth
Deficient, n = 1,459
<50.0 nmol/L
Sufficient n = 532
≥75.0 nmol/L
p-value for trend
Values are changes in Z-score or sympercent (95% confidence interval) from linear
regression models. “n =” represents number of cases per total group. Models were adjusted
for maternal age, body mass index at enrolment, educational level, history of asthma/allergy,
maternal distress, parity, smoking during pregnancy, pet keeping, folate level, midgestational season of blood sampling, child’s sex, gestational age at birth, birth weight,
breastfeeding, child’s lower respiratory tract infections, inhalant allergies, eczema, at birth
season of blood sampling, mutually for mid-gestational and cord blood 25-hydroxyvitamin D.
Table E-8. Associations of 25-hydroxyvitamin D levels with wheezing patterns and asthma of children until age 6 years according to
clinical cut-offs of 25-hydroxyvitamin D (n = 3,130)
Early Wheezing
Late Wheezing
Persistent Wheezing
Asthma
Odds Ratio
Odds Ratio
Odds Ratio
Odds Ratio
(95% CI)
(95% CI)
(95% CI)
(95% CI)
n = 604
n = 77
n = 255
n = 158
1.21 (0.92, 1.61)
1.20 (0.60, 2.41)
1.23 (0.81, 1.87)
1.20 (0.75, 1.94)
171/591
22/591
69/591
47/698
1.20 (0.92, 1.56)
1.07 (0.55, 2.07)
1.16 (0.78, 1.71)
1.09 (0.69, 1.72)
181/614
21/614
69/614
43/733
Reference
Reference
Reference
Reference
211/817
28/817
99/817
57/954
0.01
0.50
0.54
0.86
1.02 (0.62, 1.67)
n/a
0.75 (0.36, 1.54)
0.70 (0.32, 1.52)
286/1,029
35/1,029
119/1,029
75/1,219
0.89 (0.53, 1.49)
n/a
0.79 (0.38, 1.66)
0.74 (0.32, 1.72)
50-75.0 nmol/L
94/386
18/386
48/386
29/440
Optimal n = 150
Reference
Reference
Reference
Reference
30/112
1/112
15/112
10/131
0.61
0.05
0.47
0.21
25-hydroxy vitamin D in mid-gestation
Deficient, n = 856
<50.0 nmol/L
Sufficient n = 867
50-75.0 nmol/L
Optimal n = 1,138
>75.0 nmol/L
p-value for trend
25-hydroxy vitamin D at birth
Deficient, n = 1,459
<50.0 nmol/L
Sufficient n = 532
>75.0 nmol/L
p-value for trend
n/a – not applicable; Values are odds ratios (95% confidence interval) from multivariate polynomial regression and logistic regression
models. “n =” represents number of cases per total group. Models were adjusted for maternal age, body mass index at enrolment,
12
educational level, history of asthma/allergy, maternal distress, parity, smoking during pregnancy, pet keeping, folate level, midgestational season of blood sampling, child’s sex, gestational age at birth, birth weight, breastfeeding, child’s lower respiratory tract
infections, inhalant allergies, eczema, at birth season of blood sampling, mutually for mid-gestational and cord blood 25hydroxyvitamin D.
13
Figure E-1. Flowchart of participants
n = 4,236
Cohort with consent for follow-up of
Dutch subjects until age 6 years
n = 809
Data on twins (n = 135) and missing
data on 25-hydroxy vitamin D levels in
mid-gestation and at birth (n = 674)
excluded
n = 3,427
Data on any 25-hydroxyvitamin D
level in mid-gestation or at birth
available
n = 297
Missing data on all Rint, FeNO,
wheezing patterns and asthma
excluded
n =3,130
Data on Rint, FeNO, wheezing
pattern or asthma available
Rint
FeNO
Wheezing patterns
Asthma
n = 1,929
n = 1,857
n = 2,181
n = 2,591
14
15