Background
Methods
Design, setting and study population
Data collection and variables
Primary outcome measure
Explanatory factors
The recommendation of vitamin D supplementation
Ethics
Study sample
Statistics
Results
Total | Western Europea
| South Asia | Middle East | Sub-Saharan Africa | East Asia | Other | ||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
n = 748 | n = 304 | n = 189 | n = 113 | n = 51 | n = 40 | n = 51 | ||||||||
100 % | 41 % | 25 % | 15 % | 6.8 % | 5.3 % | 6.8 % | ||||||||
Pre-pregnancy maternal status | ||||||||||||||
Years of maternal age; mean (SD) | 29.9 (4.9) | 30.9 (4.5) | 28.7 (4.5) | 29.6 (5.5) | 28.1 (5.2) | 31.1 (4.5) | 29.3 (5.1) | |||||||
Parity; n (%) | ||||||||||||||
Para 0 | 340 (46) | 156 (51) | 78 (41) | 39 (35) | 22 (43) | 17 (42) | 28 (55) | |||||||
Para 1 | 259 (34) | 113 (37) | 63 (33) | 39 (35) | 11 (22) | 16 (40) | 17 (33) | |||||||
Para ≥2 | 149 (20) | 35 (12) | 48 (25) | 35 (30) | 18 (35) | 7 (18) | 6 (12) | |||||||
ᅟEducation level; n (%)b
| ||||||||||||||
ᅟᅟ<10 years | 119 (16) | 10 (3.3) | 33 (18) | 41 (36) | 22 (43) | 8 (20) | 5 (9.8) | |||||||
ᅟᅟ10-12 years | 296 (40) | 93 (30) | 95 (50) | 51 (45) | 22 (43) | 16 (40) | 19 (37) | |||||||
ᅟᅟ>12 years | 327 (44) | 199 (66) | 60 (32) | 19 (17) | 7 (14) | 16 (40) | 26 (51) | |||||||
ᅟPre-pregnancy BMIb (kg/m2); mean (SD) | 24.6 (4.8) | 24.6 (4.8) | 23.7 (4.1) | 25.8 (5.0) | 26.1 (6.1) | 22.2 (3.4) | 24.9 (5.4) | |||||||
Status at inclusion | ||||||||||||||
ᅟGestational week; mean (SD) | 15.4 (3.6) | 14.5 (2.4) | 15.9 (4.1) | 15.6 (3.3) | 17.9 (5.4) | 16.4 (4.3) | 15.5 (3.4) | |||||||
ᅟSeason of blood sample; n (%) | ||||||||||||||
ᅟᅟWinter | 395 (53) | 158 (52) | 92 (49) | 70 (62) | 32 (63) | 22 (55) | 21 (41) | |||||||
ᅟVitamin D supplements; n (%)b
| ||||||||||||||
ᅟᅟNo or <10 μg daily past two weeks | 307 (41) | 104 (34) | 93 (49) | 55 (49) | 25 (49) | 12 (30) | 18 (35) | |||||||
Status at gestational week 28 | ||||||||||||||
ᅟGestational week; mean (SD) | 28.8 (1.4) | 28.7 (1.3) | 28.7 (1.4) | 29.0 (1.6) | 29.0 (1.5) | 28.7 (1.2) | 29.0 (1.7) | |||||||
ᅟWeight gain (week 28 minus 15); mean (SD) | 6.6 (3.2) | 6.7 (2.7) | 6.5 (3.3) | 6.7 (3.6) | 4.6 (3.0) | 6.2 (2.5) | 8.0 (3.9) | |||||||
ᅟSeason of blood sample; n (%) | ||||||||||||||
ᅟᅟWinter | 410 (55) | 178 (59) | 97 (51) | 65 (57) | 28 (55) | 17 (57) | 25 (49) | |||||||
ᅟVitamin D supplements; n (%)b
| ||||||||||||||
ᅟᅟNo or <10 μg daily past two weeks | 243 (33) | 115 (38) | 41 (22) | 37 (33) | 20 (40) | 14 (35) | 16 (31) |
Vitamin D status in early pregnancy at gestational week 15
At inclusion | At gestational week 28 | |||
---|---|---|---|---|
n = 748 |
n = 748 | |||
Mean | (SD) | Mean | (SD) | |
Overall mean 25(OH)D | 50 | (27) | 59 | (29) |
Age at inclusion | ||||
≤30 years | 47 | (25) | 55 | (27) |
>30 years | 54 | (28) | 62 | (30) |
Parity (Para 0 ref) | 53 | (26) | 61 | (29) |
Para 1 | 52 | (28) | 59 | (27) |
Para ≥2 | 42 | (25) | 52 | (30) |
Western Europe (ref) | 69 | (24) | 72 | (28) |
South Asia | 32 | (19) | 46 | (23) |
Middle East | 34 | (20) | 51 | (29) |
Sub-Saharan Africa | 38 | (18) | 45 | (25) |
East Asia | 51 | (17) | 53 | (19) |
Other | 56 | (21) | 63 | (26) |
Season of blood sample | ||||
Summer | 56 | (29) | 60 | (29) |
Winter | 46 | (24) | 57 | (27) |
Education level (>12 years ref) | 60 | (27) | 67 | (27) |
10-12 years | 46 | (25) | 56 | (29) |
<10 years | 37 | (20) | 44 | (23) |
Vitamin D supplements | ||||
≥10 μga
| 57 | (26) | 61 | (28) |
No or <10 μg | 42 | (26) | 53 | (29) |
Pre-pregnancy BMI; kg/m2 (normal weight (<25) ref) | 51 | (27) | 59 | (29) |
Overweight (≥25/<30) | 51 | (27) | 61 | (31) |
Obesity (≥30) | 48 | (24) | 54 | (24) |
At inclusion | At gestational week 28 | |||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Univariate analysis | Multiple analysis | Univariate analysis | Multiple analysis | |||||||||||||||
n = 735, R2 adj. = 0.46 | n = 730, R2 adj. = 0.24 | |||||||||||||||||
Independent variable | R2 adj. | B | 95 % CI | B | 95 % CI | R2 adj. | B | 95 % CI | B | 95 % CI | ||||||||
Lower | Upper | Lower | Upper | Lower | Upper | Lower | Upper | |||||||||||
Gestational week at inclusion (<15 ref) | −0.001 | 0.01 | ||||||||||||||||
ᅟ≥15 | −0.56 | −4.4 | 3.3 |
−6.4
|
−10
|
−2.3
|
**
|
−4.6
|
−8.3
|
−0.92
|
*
| |||||||
Age at inclusion | 0.03 |
0.94
|
0.55
|
1.3
|
**
| 0.14 | −0.21 | 0.49 | 0.03 |
1.1
|
0.64
|
1.5
|
**
|
0.70
|
0.26
|
1.1
|
**
| |
Parity (para 0 ref) | 0.02 | 0.01 | ||||||||||||||||
ᅟPara1 | −1.2 | −5.4 | 3.1 | 0.24 | −3.1 | 3.6 | −2.8 | −7.4 | 1.8 |
−4.4
|
−8.7
|
−0.22
|
*
| |||||
ᅟPara ≥2 |
−11
|
−17
|
−6.3
|
**
| −3.2 | −7.6 | 1.3 |
−9.3
|
−15
|
−3.8
|
**
| −5.4 | −11 | 0.25 | ||||
Geographic region (Western Europe ref) | 0.38 | 0.16 | ||||||||||||||||
ᅟSouth Asia |
−37
|
−40
|
−33
|
**
|
−28
|
−33
|
−23
|
**
|
−26
|
−31
|
−21
|
**
|
−17
|
−23
|
−11
|
**
| ||
ᅟMiddle East |
−34
|
−39
|
−30
|
**
|
−24
|
−29
|
−18
|
**
|
−21
|
−26
|
−15
|
**
|
−9.5
|
−16
|
−2.9
|
**
| ||
ᅟSub-Saharan Africa |
−31
|
−37
|
−25
|
**
|
−20
|
−27
|
−13
|
**
|
−26
|
−34
|
−19
|
**
|
−12
|
−20
|
−3.1
|
**
| ||
ᅟEast Asia |
−17
|
−24
|
−10
|
**
|
−11
|
−18
|
−3.9
|
**
|
−19
|
−28
|
−11
|
**
|
−11
|
−20
|
−1.6
|
*
| ||
ᅟOther |
−13
|
−19
|
−6.4
|
**
|
−7.6
|
−14
|
−0.90
|
*
|
−9.0
|
−17
|
−1.3
|
*
| −1.4 | −9.6 | 6.9 | |||
Season (Summer ref) | 0.03 | 0.01 | ||||||||||||||||
ᅟWinter |
−9.9
|
−14
|
−6.1
|
**
|
−5.2
|
−8.9
|
−1.4
|
**
|
−5.7
|
−9.8
|
−1.6
|
**
| −1.3 | −6.1 | 3.4 | |||
Geographic region*Seasona
|
−11
|
−16
|
−4.8
|
**
|
−15
|
−22
|
−7.4
|
**
| ||||||||||
Education level (>12 y ref) | 0.11 | 0.08 | ||||||||||||||||
ᅟ10-12 year |
−14
|
−18
|
−10
|
**
|
−3.7
|
−7.1
|
−0.30
|
*
|
−11
|
−15
|
−6.8
|
**
| −1.8 | −6.1 | 2.5 | |||
ᅟ<10 year |
−23
|
−28
|
−17
|
**
|
−5.2
|
−10
|
−0.31
|
*
|
−23
|
−29
|
−17
|
**
|
−8.6
|
−15
|
−2.5
|
**
| ||
Vitamin D supplements (≥10μgb ref) | 0.08 | 0.02 | ||||||||||||||||
ᅟNo or <10 μg |
−15
|
−19
|
−11
|
**
|
−11
|
−14
|
−7.7
|
**
|
−8.2
|
−13
|
−3.8
|
**
|
−9.8
|
−14
|
−5.8
|
**
| ||
Pre-pregnancy BMI (<25 kg/m2ref) | −0.001 | −0.001 | ||||||||||||||||
ᅟ≥25 kg/m2
| −0.76 | −4.7 | 3.2 | −0.11 | −4.4 | 4.2 |