Introduction
Method
Study design and participants
Data collection
Vitamin D level assessment and classification
Maternal and neonatal outcomes
Statistical analysis
Results
General description of vitamin D status
Maternal 25(OH)D status | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Mean(95%CI) | Middle | SE | Min | Max | 5th | 10th | 25th | 50th | 75th | 90th | 95th |
43.17 ± .10 | 42.00 | 15.81 | 2.00 | 124.00 | 20.20 | 23.60 | 30.80 | 42.00 | 53.70 | 64.30 | 70.70 |
Clinical characteristics
Maternal Characteristic | 25(OH)D status (nmol/L) | χ2/H P- value | |||
---|---|---|---|---|---|
< 50 (N = 15,696) | 50–75 (N = 6981) | > 75 (N = 717) | Total (N = 23,394) | ||
Maternal Age(years) | 59.154 <.001* | ||||
<24b | 456(2.90) | 178(2.50) | 8(1.10) | 642(2.70) | |
25-29a | 6894(43.90) | 2807(40.20) | 286(39.90) | 9987(42.70) | |
30-34ab | 6319(40.30) | 2928(41.90) | 294(41.00) | 9541(40.80) | |
≥35ac | 2027(12.90) | 1068(15.30) | 129(18.00) | 3224(13.80) | |
Pre-pregnancy BMI (kg/m2) | 141.771 <.001* | ||||
< 18.5abc | 1932(12.30) | 1037(14.90) | 170(23.70) | 3139(13.40) | |
18.5–23.9bc | 11,448(72.90) | 5142(73.70) | 493(68.80) | 17,083(73.00) | |
≥24abc | 2316(14.80) | 802(11.50) | 54(7.50) | 3172(13.60) | |
Season of blood collection | 397.256 <.001* | ||||
Spring | 4087(26.00) | 1620(23.20) | 171(23.8) | 5878(25.10) | |
Summer | 3268(20.80) | 2055(29.40) | 229(31.9) | 5552(23.70) | |
Autumn | 3835(24.40) | 1928(27.60) | 221(29.4) | 5974(25.50) | |
Winter | 4506(28.70) | 1378(19.70) | 106(14.8) | 5990(25.60) | |
No. of previous pregnancies | 14.132 .007* | ||||
0 | 10,251(63.50) | 4433(63.50) | 451(62.90) | 15,135(64.70) | |
1 | 3817(24.30) | 1732(24.80) | 173(24.10) | 5722(24.50) | |
2 | 1628(10.40) | 816(11.70) | 93(13.00) | 2537(10.80) | |
Male fetus | 8033(51.20) | 3649(52.30) | 381(53.10) | 12,306(51.60) | 3.040 .219* |
Family history of diabetes | 1314(8.40) | 579(8.30) | 56(7.80) | 1914(8.33) | .301 .860* |
Family history of thyroid disease | 3 | 7 | 0 | – | – |
Maternal Age(years) (Mean ± SD)ab | 30.30 ± 3.64 | 30.64 ± 3.70 | 30.93 ± 3.69 | 30.42 ± 3.66 | 58.510 <.001# |
Pre-pregnancy BMI (kg/m2) (Mean ± SD)abc | 21.23 ± 2.77 | 20.87 ± 2.62 | 20.15 ± 2.25 | 21.09 ± 2.72 | 58.643 <.001# |
Maternal outcomes
Maternal Outcomes | 25(OH)D status(nmol/L) | χ2/F/H P- value | |||
---|---|---|---|---|---|
< 50 (N = 15,696) | 50–74.9 (N = 6981) | ≥75 (N = 717) | Total (N = 23,394) | ||
Gestational Age (weeks) (Mean±SD)a | 38.9 ± 1.4 | 38.9 ± 1.4 | 38.8 ± 1.2 | 38.9 ± 1.4 | 3.327 .036& |
Gestational Age(weeks) (Category) | 8.023 .431* | ||||
< 28 | 3 | 0 | 0 | 3 | |
28–31 + 6 | 54(0.3) | 26(0.4) | 0 | 80(0.3) | |
32–33 + 6 | 101(0.6) | 31(0.4) | 4(0.6) | 136(0.6) | |
34–36 + 6 | 692(4.4) | 324(4.6) | 32(4.5) | 1048(4.5) | |
≥37 | 14,846(94.6) | 6600(94.5) | 681(95.0) | 22,127(94.6) | |
Cesarean section | 6715(42.8) | 3028(43.4) | 301(42.0) | 10,044(42.9) | 0.969 .616* |
Premature rupture of membranes | 18(0.1) | 12(0.2) | 0 | 30(0.1) | 2.185 .335* |
Gestational diabetesa | 1680(10.7) | 831(11.9) | 73(10.2) | 2584(11.0) | 7.648 .022* |
Preeclampsia | 440(1.9) | 162(2.3) | 11(1.5) | 613(2.6) | 7.832 .020* |
Intrahepatic cholestasis | 108(0.7) | 38(0.5) | 8(1.1) | 154(0.7) | 3.894 .143* |
Intrauterine infection | 330(2.1) | 115(1.6) | 10(1.4) | 455(1.9) | 6.422 .040* |
2-h postpartum hemorrhage(ml) | 256 ± 149 | 255 ± 106 | 244 ± 84 | 255 ± 137 | .001 .797# |
Neonatal outcomes
Neonatal Outcomes | Maternal 25(OH)D status(nmol/L) | χ2/F/H P-value | |||
---|---|---|---|---|---|
< 50 (N = 15,696) | 50–75 (N = 6981) | > 75 (N = 717) | Total (N = 23,394) | ||
Birth weight (Mean ± SD) | 3346 ± 448 | 3340 ± 437 | 3329 ± 412 | 3343 ± 443 | .833 .435& |
Birth weight z score (Mean ± SD) | .005 ± 1.010 | −.008 ± .985 | −.032 ± .928 | – | |
Low birth weight: < 2500 g | 372(2.4) | 141(2.0) | 14(2.0) | 527(2.3) | 2.995 .224* |
Very low birth weight: < 1500 g | 42(0.3) | 20(0.3) | 1(0.1) | 63(0.3) | 0.529 .768* |
Small for gestational age: <10th percentile (3 case excluded) | 322(2.1) | 135(1.9) | 15(2.1) | 472(2.0) | 1.833 .766* |
High birth weight: > 4000 g | 955(6.1) | 390(5.6) | 38(5.3) | 1383(5.9) | 2.650 .266* |
Large for gestational age: >90th percentile | 3679(23.4) | 1612(23.1) | 160(22.3) | 5451(23.3) | 2.212 .697* |
Birth length (Mean ± SD) | 49.9 ± 1.4 | 49.8 ± 1.4 | 49.9 ± 1.1 | 49.9 ± 1.4 | .689 .502& |
Apgar score (Mean ± SD) | 9.7 ± .9 | 9.7 ± 1.0 | 9.7 ± .8 | 9.7 ± .9 | 1.938 .144& |
Apgar score | 7.144 .308* | ||||
0–3 | 28(.2) | 17(.2) | 0 | 45(.2) | – |
4–6 | 106(.7) | 43(.6) | 2(.3) | 151(.6) | |
7–8 | 270(1.7) | 137(2.0) | 9(1.3) | 416(1.8) | |
9–10 | 15,292(97.4) | 6784(97.2) | 706(98.5) | 22,782(97.4) | |
Admission to neonatal intensive care unit | 1918(12.2) | 761(10.9) | 67(9.3) | 2746(11.7) | 12.200 .002* |
Admission to neonatal intensive care unit (Mean ± SD) | 6.2 ± 4.1 | 5.9 ± 3.1 | 5.1 ± 2.1 | 6.1 ± 3.2 | .010# |
Any respiratory disorders¶ | 334(2.1) | 131(1.9) | 16(2.2) | 481(2.1) | 1.205 .300* |
Dyspnea (clinical diagnosis) | 8(0.1) | 5(0.1) | 0 | 13(0.1) | .782 .676* |
Wet lung | 266(1.7) | 107(1.5) | 13(1.8) | 386(1.6) | .902 .637* |
Aspiration pneumonia | 5 | 3 | 0 | 8 | – |
Pulmonary arterial hypertension | 2 | 0 | 0 | 2 | – |
Pneumothorax | 30(0.2) | 6(0.1) | 1(0.1) | 37(0.2) | 3.402 .183* |
Bronchopulmonary dysplasia | 2 | 0 | 0 | 2 | – |
Neonatal convulsion | 6 | 6 | 1 | 13 | – |
Hyperbilirubinemia | 971(6.2) | 434(6.2) | 30(4.2) | 1435(6.1) | 4.487 .087* |
Necrotizing enterocolitis | 79(0.5) | 26(0.4) | 4(0.6) | 109(0.5) | 1.919 .383* |
Sepsis | 29(0.2) | 14(0.2) | 2(0.3) | 45(0.2) | – |
Retinopathy of prematurity | 19 | 7 | 0 | 26 | – |
Neonatal death | 1 | 1 | 0 | 2 | – |
Unadjusted and adjusted risk factors analysis
Unadjusted OR (95% CI) and P Value | Adjusted ORa (95% CI) And P Value | |||||
---|---|---|---|---|---|---|
Maternal outcomes | ≥75 | 50–74.9 | < 50 | ≥75 | 50–74.9 | < 50 |
Preterm birth | 1.00 - | 1.092(.769–1.551) .623 | 1.086(.771–1.529) .637 | 1.00 - | 1.080(.760–1.535) .667 | 1.078(.765–1.520) .667 |
Gestational diabetes | 1.00 - | 1.192(.926–1.535) .173 | 1.057(.826–1.354) .658 | 1.00 - | 1.145(.886–1.478) .300 | 1.014(.789–1.303) .915 |
Preeclampsia | 1.00 - | 1.525(.824–2.822) .179 | 1.851(1.013–3.383) .045 | 1.00 - | 1.387(.748–2.571) .299 | 1.609(.879–2.948) .123 |
Intrauterine inflammation | 1.00 - | 1.184(.618–2.270) .611 | 1.518(.806–2.861) .196 | 1.00 - | 1.187(.618–2.278) .607 | 1.545(.817–2.920) .181 |
Cesarean section | 1.00 - | 1.059(.906–1.237) .437 | 1.033(.888–1.203) .672 | 1.00 - | 1.049(.895–1.230) .556 | 1.040(.890–1.214) .622 |
Intrahepatic cholestasis | 1.00 - | .485(.225–1.044) .064 | .614(.298–1.264) .186 | 1.00 - | .501(.232–1.079) .078 | .633(.306–1.308) .217 |
Neonatal outcomes | ||||||
Low birth weight | 1.00 - | 1.035(.594–1.803) .903 | 1.219(.711–2.090) .471 | 1.00 - | 1.055(.606–1.839) .849 | 1.263(.736–2.169) .397 |
Small for gestational age | 1.00 - | .923(.538–1.582) .770 | .980(.581–1.654) .941 | 1.00 - | .991(.822–1.196) .927 | .999(.832–1.199) .989 |
Large for gestational age | 1.00 - | 1.045(.869–1.257) .638 | 1.066(.891–1.276) .485 | 1.00 - | .978(.569–1.678) .935 | 1.060(.626–1.793) .829 |
Admission to neonatal intensive care unit | 1.00 - | 1.187(.913–1.543) .201 | 1.350(1.045–1.744) .022 | 1.00 - | 1.160(.892–1.509) .269 | 1.305(1.010–1.687) .042 |
Any respiratory disorders | 1.00 - | .838(.496–1.416) .509 | .950(.572–1.578) .842 | 1.00 - | .824(.487–1.394) .470 | .937(.563–1.559) .803 |
Hyperbilirubinemia | 1.00 - | 1.518(1.042–2.189) .031 | 1.510(1.042–2.189) .030 | 1.00 - | 1.451(.993–2.118) .054 | 1.397(.963–2.027) .079 |
Necrotizing enterocolitis | 1.00 - | .666(.232–1.915) .451 | .902(.329–2.469) .840 | 1.00 - | .684(.238–1.969) .482 | .947(.345–2.603) .916 |
Sepsis | 1.00 - | .718(.163–3.167) .662 | .662(.158–2.779) .662 | 1.00 - | .668(.151–2.951) .594 | .597(.141–2.523) .483 |
Maternal characteristics and Pregnant outcomes | Admission to neonatal intensive care unit | χ2/Z/ P- value | |
---|---|---|---|
Without (N = 20,648) | With (N = 2746) | ||
25(OH)D levels (Mean ± SD) | 43.283 ± 15.893 | 42.319 ± 15.183 | −2.590 .010& |
25(OH)D levels (N%) | 12.200 .002* | ||
<50a | 13,778 (66.7) | 1918 (69.8) | |
50–74.9a | 6220 (30.1) | 761 (27.7) | |
≥75a | 650 (3.1) | 67(2.4) | |
Maternal Age(years) (Mean ± SD) | 30.5 ± 3.7 | 30.2 ± 3.5 | −2.759 .006& |
Maternal Age(years) (N(%)) | 17.364 .001* | ||
<24a | 628 (2.8) | 14 (2.1) | |
25-29a | 9775 (42.4) | 212 (44.9) | |
30–34 | 9351 (40.7) | 244 (41.2) | |
≥35a | 3165 (14.1) | 114 (11.7) | |
Pre-pregnancy BMI (kg/m2) (Mean ± SD) | 20.8 ± 3.6 | 21.1 ± 3.4 | 20.731 <.001# |
Pre-pregnancy BMI (kg/m) (N(%)) | |||
< 18.5a | 2813 (13.6) | 326 (11.9) | |
18.5–23.9 | 15,105 (73.2) | 1978 (72.0) | |
≥24a | 2730(13.2) | 442 (16.1) | |
Season of blood collection | 8.109 .044* | ||
Spring a | 5132(24.9) | 746 (27.2) | |
Summer | 4910 (23.8) | 642 (23.4) | |
Autumn | 5314 (25.7) | 660 (24.0) | |
Winter | 5292(25.6) | 698 (25.4) | |
No. of previous pregnancies | 4.758 .093* | ||
0a | 13,311 (64.5) | 1824 (66.4) | |
1 | 5072 (24.6) | 650 (23.7) | |
2+ | 2265 (11.0) | 272 (9.9) | |
Gestational age at birth, weeks (Mean ± SD) | 39.0 ± 1.2 | 38.2 ± 2.4 | −10.445 <.001& |
Gestational age at birth (N(%)) | 1976.277 <.001* | ||
< 28 | 2 | 1 | |
28–31 + 6 | 32 (.2) | 48 (1.7) | |
32–33 + 6 | 13 (.1) | 123 (4.5) | |
34–36 + 6 | 614 (3.0) | 434 (15.8) | |
≥37 | 19,987 (96.8) | 2140 (83.5) | |
Male (N%) | 10,600 (51.3) | 1463 (53.3) | 3.655 .056* |
Cesarean section (N%) | 8975 (43.5) | 1069 (38.9) | 22.366 <.001* |
2-h postpartum hemorrhage(ml) | 241 ± 155 | 255 ± 137 | −7.964 <.001& |
Apgar score(Mean ± SD) | 9.9 ± .6 | 9.7 ± .9 | −18.128 <.001& |
Apgar score (N%) | 233.297 <.001* | ||
0–3 | 37(.2) | 8(.3) | |
4-6a | 97(.5) | 54(2.0) | |
7-8a | 289(1.4) | 127(4.6) | |
9-10a | 20,225(98.0) | 2557(93.1) | |
Neonatal birth weight(g) | 3366 ± 409 | 3172 ± 619 | −12.208 <.001& |
Neonatal birth height(cm) | 49.9 ± 1.1 | 49.2 ± 2.4 | −12.976 <.001& |