Table 1. Characteristics of study participants (N =27,768)
Characteristics
|
Statistics
|
25OHD,
Mean (SD) , ng/mL
|
β (95%CI)a
|
P-valuea
|
Maternal serum 25OHD concentrations during pregnancy continuous, Mean (SD) Median (Q1-Q3), ng/mL
|
17.7 (7.9)
16.0 (12.0-22.0)
|
|
|
|
Maternal serum 25OHD concentrations during pregnancy categorical, N (%)
|
|
|
|
|
Deficiency (< 12 ng/mL)
|
6532 (23.5%)
|
|
|
|
Inadequacy (>= 12, < 20 ng/mL)
|
11465 (41.3%)
|
|
|
|
Adequacy ( >= 20 ng/mL)
|
9771 (35.2%)
|
|
|
|
Age tertile, N (%)
|
|
|
|
|
Tertile 1 (15 - 26 y)
|
8605 (30.99%)
|
17.18 (7.70)
|
Reference
|
-
|
Tertile 2 (27 - 29 y)
|
7948 (28.62%)
|
17.57 (7.85)
|
0.39 (0.15, 0.63)
|
0.0013
|
Tertile 3 (30 - 47 y)
|
11215 (40.39%)
|
18.08 (8.03)
|
0.90 (0.68, 1.12)
|
<0.0001
|
P for trend
|
|
|
|
<0.0001
|
Year of blood collection , N (%)
|
|
|
|
|
2016
|
5943 (21.40%)
|
16.28 (7.45)
|
Reference
|
-
|
2017
|
7410 (26.69%)
|
18.10 (7.65)
|
1.82 (1.55, 2.08)
|
<0.0001
|
2018
|
5616 (20.22%)
|
17.68 (8.52)
|
1.40 (1.11, 1.68)
|
<0.0001
|
2019
|
5204 (18.74%)
|
18.38 (7.96)
|
2.10 (1.81, 2.39)
|
<0.0001
|
2020
|
3595 (12.95%)
|
17.94 (7.65)
|
1.65 (1.33, 1.98)
|
<0.0001
|
P for trend
|
|
|
|
< 0.0001
|
Month of blood collection, N (%)
|
|
|
|
|
January
|
2161 (7.78%)
|
13.83 (7.02)
|
Reference
|
-
|
February
|
1549 (5.58%)
|
13.65 (6.69)
|
-0.18 (-0.66, 0.29)
|
0.4535
|
March
|
2285 (8.23%)
|
14.37 (6.91)
|
0.54 (0.11, 0.97)
|
0.0133
|
April
|
2676 (9.64%)
|
16.19 (7.24)
|
2.36 (1.95, 2.77)
|
<0.0001
|
May
|
2578 (9.28%)
|
15.76 (6.80)
|
1.93 (1.52, 2.35)
|
<0.0001
|
June
|
2505 (9.02%)
|
18.98 (7.23)
|
5.15 (4.73, 5.56)
|
<0.0001
|
July
|
2617 (9.42%)
|
20.05 (7.39)
|
6.22 (5.81, 6.64)
|
<0.0001
|
August
|
2381 (8.57%)
|
22.10 (7.97)
|
8.27 (7.85, 8.70)
|
<0.0001
|
September
|
2276 (8.20%)
|
22.45 (8.09)
|
8.62 (8.19, 9.05)
|
<0.0001
|
October
|
2183 (7.86%)
|
20.65 (7.78)
|
6.82 (6.38, 7.25)
|
<0.0001
|
November
|
2273 (8.19%)
|
17.53 (7.27)
|
3.70 (3.27, 4.13)
|
<0.0001
|
December
|
2284 (8.23%)
|
14.79 (6.74)
|
0.96 (0.53, 1.39)
|
<0.0001
|
P for trend
|
|
|
|
< 0.0001
|
Season of blood collection, N (%)
|
|
|
|
|
Spring (March, April and May)
|
7539 (27.15%)
|
15.49 (7.03)
|
Reference
|
-
|
Summer (June, July and August)
|
7503 (27.02%)
|
20.34 (7.64)
|
4.85 (4.61, 5.09)
|
<0.0001
|
Autumn (September, October and November)
|
6732 (24.24%)
|
20.20 (7.98)
|
4.71 (4.47, 4.95)
|
<0.0001
|
Winter (December, January and February)
|
5994 (21.59%)
|
14.15 (6.85)
|
-1.34 (-1.60, -1.09)
|
<0.0001
|
P for trend
|
|
|
|
< 0.0001
|
Abbreviations: 25OHD, 25-hydroxy vitamin D; OR, odds ratio; CI, confidence interval; SD, standard deviation.
aCrude associations with maternal serum 25OHD concentrations during pregnancy continuous.
Table 2. Associations of the maximum cumulative effects of PM and maternal serum 25OHD levels during the second trimester in models adjusted for different temporal and meteorological factors
Model
|
β (95% CI)
P-value
|
45-day moving daily average PM2.5 concentration
|
60-day moving daily average PM10 concentration
|
Crude Modela
|
-0.200 (-0.206, -0.193) <0.00001
|
-0.142 (-0.146, -0.137) <0.00001
|
Model 1 (Age + Year + Season)b
|
-0.113 (-0.125, -0.101) <0.00001
|
-0.090 (-0.099, -0.081) <0.00001
|
Model 2 (Model 1 + Atmospheric Pressure)c
|
-0.042 (-0.055, -0.028) <0.00001
|
-0.039 (-0.049, -0.030) <0.00001
|
Model 3 (Model 2 + Sunshine Duration)d
|
-0.039 (-0.053, -0.026) <0.00001
|
-0.046 (-0.055, -0.036) <0.00001
|
Model 4 (Model 3 + Relative Humidity +Wind Speed)e
|
-0.032 (-0.046, -0.018) <0.00001
|
-0.039 (-0.049, -0.028) <0.00001
|
aNo adjusted.
bAdjusted for year, age and season.
cAdjusted for year, age, season, and corresponding-day moving daily average atmospheric pressure.
dAdjusted for year, age, season, the corresponding-day moving daily average atmospheric pressure and sunshine duration.
eAdjusted for year, age, season, the corresponding-day moving daily average atmospheric pressure, sunshine duration, relative humidity and wind speed.
Abbreviations: PM, particulate matter; PM2.5, particulate matter with an aerodynamic diameter of ≤2.5 μm; PM10, particulate matter with an aerodynamic diameter of ≤10 μm; 25OHD, 25-hydroxy vitamin D; CI, confidence interval.
Table 3A. Threshold effect analysis examining associations between 45-day moving daily average PM2.5 levels and maternal serum 25OHD levels during second trimester in subgroups stratified by season of blood collection
|
Spring
|
Summer
|
Autumn
|
Winter
|
Total
|
Model Aa
|
|
|
|
|
P-interaction: <0.001
|
One line slope, β (95%CI) P-value
|
-0.027 (-0.069, 0.014) 0.1919
|
-0.187 (-0.247, -0.128) <0.0001
|
-0.173 (-0.250, -0.097) <0.0001
|
-0.029 (-0.051, -0.006) 0.0136
|
-0.032 (-0.046, -0.018) <0.0001
|
Model Bb
|
|
|
|
|
P-interaction: <0.001
|
Turning point (K), μg/m3
|
38.62
|
35.4
|
31.11
|
46.31
|
20.07
|
< K, β (95%CI) P-value
|
-0.229 (-0.331, -0.127) <0.0001
|
-0.348 (-0.427, -0.268) <0.0001
|
0.020 (-0.086, 0.125) 0.7130
|
-0.130 (-0.192, -0.068) <0.0001
|
-1.798 (-2.065, -1.532) <0.0001
|
> K, β (95%CI) P-value
|
0.080 (0.016, 0.145) 0.0150
|
0.169 (0.038, 0.300) 0.0115
|
-0.552 (-0.713, -0.390) <0.0001
|
-0.013 (-0.038, 0.011) 0.2825
|
-0.022 (-0.036, -0.008) 0.0018
|
Slope 2 – Slope 1, β (95%CI) P-value
|
0.309 (0.166, 0.452) <0.0001
|
0.516 (0.347, 0.685) <0.0001
|
-0.571 (-0.787, -0.356) <0.0001
|
0.117 (0.050, 0.183) 0.0006
|
1.776 (1.509, 2.044) <0.0001
|
Predicted 25OHD levels at K (95% CI), ng/mL
|
15.977 (15.655, 16.298)
|
18.303 (17.982, 18.625)
|
19.469 (19.137, 19.802)
|
14.284 (14.024, 14.543)
|
20.635 (20.488, 20.782)
|
LRTc, P-value
|
<0.001
|
<0.001
|
<0.001
|
<0.001
|
<0.001
|
Adjusted for year, age, 45-day moving daily average atmospheric pressure, sunshine duration, relative humidity and wind speed.
aLinear analysis, P-value <0.05 indicates a linear relationship.
bNon-linear analysis.
cP <0.05 means Model B is significantly different from Model A, which indicates a non-linear relationship.
Abbreviations: PM2.5, particulate matter with an aerodynamic diameter of ≤2.5 μm; 25OHD, 25-hydroxy vitamin D; CI, confidence interval; LRT, logarithmic likelihood ratio test.
Table 3B. Threshold effect analysis examining associations between 60-day moving daily average PM10 level and maternal serum 25OHD levels during second trimester in subgroups stratified by season of blood collection
|
Spring
|
Summer
|
Autumn
|
Winter
|
Total
|
Model Aa
|
|
|
|
|
P-interaction: <0.001
|
One line slope, β (95%CI) P-value
|
-0.102 (-0.142, -0.061) <0.0001
|
-0.058 (-0.098, -0.019) 0.0040
|
-0.003 (-0.062, 0.057) 0.9227
|
-0.023 (-0.044, -0.002) 0.0313
|
-0.039 (-0.049, -0.028) <0.0001
|
Model Bb
|
|
|
|
|
P-interaction: 0.383
|
Turning point (K), μg/m3
|
93.15
|
45.07
|
38.10
|
113.18
|
38.28
|
< K, β (95%CI) P-value
|
-0.080 (-0.122, -0.038) 0.0002
|
-0.310 (-0.430, -0.189) <0.0001
|
-1.121 (-1.513, -0.728) <0.0001
|
-0.012 (-0.034, 0.010) 0.2946
|
-0.711 (-0.841, -0.580) <0.0001
|
> K, β (95%CI) P-value
|
-0.530 (-0.734, -0.325) <0.0001
|
-0.030 (-0.071, 0.012) 0.1648
|
-0.046 (-0.108, 0.015) 0.1383
|
-0.379 (-0.576, -0.182) 0.0002
|
-0.038 (-0.049, -0.027) <0.0001
|
Slope 2 – Slope 1, β (95%CI) P-value
|
-0.450 (-0.661, -0.239) <0.0001
|
0.280 (0.154, 0.407) <0.0001
|
1.074 (0.702, 1.447) <0.0001
|
-0.367 (-0.570, -0.165) 0.0004
|
0.673 (0.542, 0.803) <0.0001
|
Predicted 25OHD levels at K (95% CI), ng/mL
|
14.927 (14.625, 15.230)
|
20.666 (20.345, 20.988)
|
20.828 (20.475, 21.180)
|
12.769 (12.366, 13.172)
|
20.950 (20.789, 21.112)
|
LRTc, P-value
|
<0.001
|
<0.001
|
<0.001
|
<0.001
|
<0.001
|
Adjusted for year, age, 60-day moving daily average atmospheric pressure, sunshine duration, relative humidity and wind speed.
aLinear analysis, P-value <0.05 indicates a linear relationship.
bNon-linear analysis.
cP <0.05 means Model B is significantly different from Model A, which indicates a non-linear relationship.
Abbreviations: PM10, particulate matter with an aerodynamic diameter of ≤10 μm; 25OHD, 25-hydroxy vitamin D; CI, confidence interval; LRT, logarithmic likelihood ratio test.
Table 4A. Associations between 45-day moving daily average PM2.5 levels and maternal serum 25OHD levels during second trimester of pregnancy in subgroups stratified by meteorological factors
|
N
|
β (95% CI) P-value
|
P-value for interaction
|
45-day moving daily average atmospheric pressure
|
|
|
<0.0001
|
Tertile 1 (1002.65 - 1010.69 hPa)
|
9247
|
-0.191 (-0.250, -0.132) <0.0001
|
|
Tertile 2 (1010.74 - 1020.73 hPa)
|
9260
|
-0.042 (-0.077, -0.007) 0.0193
|
|
Tertile 3 (1020.75 - 1028.82 hPa)
|
9261
|
-0.023 (-0.041, -0.005) 0.0141
|
|
45-day moving daily average relative humidity
|
|
|
<0.0001
|
Tertile 1 (62.58 - 71.11 %)
|
9220
|
0.140 (0.105, 0.175) <0.0001
|
|
Tertile 2 (71.13 - 77.04 %)
|
9275
|
-0.086 (-0.111, -0.060) <0.0001
|
|
Tertile 3 (77.07 - 94.33 %)
|
9273
|
-0.135 (-0.169, -0.102) <0.0001
|
|
45-day moving daily average sunshine duration
|
|
|
<0.0001
|
Tertile 1 (1.28 - 4.10 hours)
|
9136
|
-0.044 (-0.064, -0.024) <0.0001
|
|
Tertile 2 (4.12 - 5.14 hours)
|
9303
|
-0.030 (-0.063, 0.003) 0.0717
|
|
Tertile 3 (5.15 - 8.68 hours)
|
9329
|
-0.190 (-0.242, -0.137) <0.0001
|
|
45-day moving daily average wind speed
|
|
|
0.2390
|
Tertile 1 (1.36 - 1.87 m/s)
|
9138
|
-0.068 (-0.088, -0.049) <0.0001
|
|
Tertile 2 (1.88 - 2.12 m/s)
|
9117
|
-0.040 (-0.069, -0.011) 0.0066
|
|
Tertile 3 (2.13 - 2.65 m/s)
|
9513
|
-0.047 (-0.091, -0.004) 0.0331
|
|
Adjusted for year, season, 45-day moving daily average atmospheric pressure, sunshine duration, relative humidity and wind speed except the subgroup variable.
Abbreviations: PM2.5, particulate matter with an aerodynamic diameter of ≤2.5 μm; 25OHD, 25-hydroxy vitamin D; CI, confidence interval.
Table 4B. Associations between 60-day moving daily average PM10 levels and maternal serum 25OHD levels during second trimester of pregnancy in subgroups stratified by meteorological factors
|
N
|
β (95% CI) P-value
|
P-value for interaction
|
60-day moving daily average atmospheric pressure
|
|
|
<0.0001
|
Tertile 1 (1003.24 - 1010.76 hPa)
|
9241
|
-0.154 (-0.190, -0.118) <0.0001
|
|
Tertile 2 (1010.78 - 1020.92 hPa)
|
9270
|
-0.132 (-0.157, -0.108) <0.0001
|
|
Tertile 3 (1020.97 - 1028.09 hPa)
|
9257
|
-0.021 (-0.037, -0.005) 0.0100
|
|
60-day moving daily average relative humidity
|
|
|
<0.0001
|
Tertile 1 (63.32 - 71.30 %)
|
9189
|
0.071 (0.044, 0.099) <0.0001
|
|
Tertile 2 (71.32 - 77.18 %)
|
9289
|
-0.053 (-0.071, -0.035) <0.0001
|
|
Tertile 3 (77.23 - 92.27 %)
|
9290
|
-0.074 (-0.096, -0.051) <0.0001
|
|
60-day moving daily average sunshine duration
|
|
|
<0.0001
|
Tertile 1 (1.84 - 4.07 hours)
|
9237
|
-0.026 (-0.043, -0.008) 0.0034
|
|
Tertile 2 (4.08 - 5.15 hours)
|
9234
|
-0.057 (-0.078, -0.035) <0.0001
|
|
Tertile 3 ( 5.16 - 7.90 hours)
|
9297
|
-0.128 (-0.157, -0.099) <0.0001
|
|
60-day moving daily average wind speed
|
|
|
0.0032
|
Tertile 1 (1.34 - 1.89 m/s)
|
8993
|
-0.043 (-0.059, -0.027) <0.0001
|
|
Tertile 2 (1.90 - 2.11 m/s)
|
9306
|
-0.078 (-0.102, -0.054) <0.0001
|
|
Tertile 3 (2.12 - 2.58 m/s)
|
9469
|
-0.094 (-0.124, -0.065) <0.0001
|
|
Adjusted for year, season, 60-day moving daily average atmospheric pressure, sunshine duration, relative humidity and wind speed except the subgroup variable.
Abbreviations: PM10, particulate matter with an aerodynamic diameter of ≤10 μm; 25OHD, 25-hydroxy vitamin D; CI, confidence interval.