Background
Methods
Study population
Primary outcome measures
Statistical analyses
Results
Full Term (N = 11,354) | Preterm (N = 975) | Total (N = 12,340) | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
BV exposed | BV unexposed | BV exposed | BV unexposed | BV exposed | BV unexposed | |||||||
N = 2198 | N = 9156 | N = 267 | N = 708 | N = 2468 | N = 9872 | |||||||
n
|
%
|
n
|
%
|
n
|
%
|
n
|
%
|
n
|
%
|
n
|
%
| |
Age (years)* | ||||||||||||
<20 | 324 |
14.7
| 666 |
7.3
| 39 |
14.6
| 56 |
7.9
| 363 |
14.7
| 723 |
7.3
|
20-24 | 784 |
35.7
| 2095 |
22.9
| 79 |
29.6
| 179 |
25.3
| 866 |
35.1
| 2278 |
23.1
|
25-29 | 620 |
28.2
| 2593 |
28.3
| 66 |
24.7
| 166 |
23.5
| 686 |
27.8
| 2760 |
28.0
|
30-34 | 317 |
14.4
| 2375 |
26.0
| 44 |
16.5
| 188 |
26.6
| 361 |
14.6
| 2564 |
26.0
|
35+ | 153 |
7.0
| 1424 |
15.6
| 39 |
14.6
| 119 |
16.8
| 192 |
7.8
| 1544 |
15.6
|
Race/Ethnicity* | ||||||||||||
White | 1268 |
58.8
| 6842 |
71.7
| 152 |
58.9
| 497 |
71.8
| 1422 |
58.8
| 6981 |
71.7
|
Black | 231 |
10.7
| 416 |
4.6
| 21 |
8.1
| 36 |
5.2
| 252 |
10.4
| 452 |
4.6
|
Asian | 183 |
8.5
| 939 |
10.4
| 28 |
10.9
| 64 |
9.3
| 212 |
8.8
| 1006 |
10.3
|
Hispanic | 410 |
19.0
| 979 |
10.8
| 39 |
15.1
| 73 |
10.6
| 449 |
18.6
| 1054 |
10.8
|
Native American | 62 |
2.9
| 218 |
2.4
| 18 |
7.0
| 22 |
3.2
| 80 |
3.3
| 240 |
2.5
|
Other | 4 |
0.2
| 9 |
0.1
| 0 |
0.0
| 0 |
0.0
| 4 |
0.2
| 9 |
0.1
|
Education* | ||||||||||||
Less than H.S. | 689 |
31.6
| 1639 |
18.1
| 89 |
34.1
| 148 |
21.4
| 779 |
31.9
| 1791 |
18.4
|
H.S. grad/some college | 1132 |
51.9
| 4134 |
45.8
| 129 |
49.4
| 323 |
46.6
| 1263 |
51.7
| 4460 |
45.8
|
College graduate | 360 |
16.5
| 3263 |
36.1
| 43 |
16.5
| 222 |
32.0
| 403 |
16.5
| 3486 |
35.8
|
Nulliparous* | 3733 |
47.2
| 1035 |
41.4
| 118 |
45.2
| 309 |
45.2
| 1154 |
47.0
| 4045 |
41.7
|
Cesarean delivery* | 477 |
21.7
| 2479 |
27.1
| 78 |
29.3
| 269 |
38.1
| 555 |
22.5
| 2751 |
27.9
|
Low Birth Weight (<2500 g)* | 41 |
1.9
| 139 |
1.5
| 158 |
60.1
| 344 |
49.1
| 199 |
8.1
| 483 |
4.9
|
Small for gestational age | 227 |
10.3
| 790 |
8.6
| 22 |
8.2
| 76 |
10.7
| 249 | 10.1 | 866 |
8.8
|
missing | 0 |
(0)
| 12 |
(0.13)
| 20 |
(7.49)
| 15 |
(2.12)
| 23 | (0.93) | 35 |
(0.35)
|
Smoking* | 360 |
16.5
| 921 |
10.1
| 42 |
15.9
| 84 |
12.0
| 404 |
16.5
| 1006 |
10.3
|
Kotelchuck Index | ||||||||||||
Inadequate | 374 |
17.8
| 1203 |
15.2
| 29 |
14.2
| 85 |
16.7
| 403 |
17.5
| 1291 |
15.3
|
Intermediate | 475 |
22.6
| 1763 |
22.3
| 39 |
19.1
| 76 |
14.9
| 514 |
22.3
| 1839 |
21.8
|
Adequate | 899 |
42.7
| 3658 |
46.3
| 52 |
25.5
| 150 |
29.5
| 951 |
41.2
| 3808 |
45.2
|
Adequate Plus | 356 |
16.9
| 1283 |
16.2
| 84 |
41.2
| 198 |
38.9
| 440 |
19.1
| 1481 |
17.6
|
missing | 94 |
(4.3)
| 1249 |
(13.6)
| 63 |
(23.6)
| 199 |
(28.1)
| 160 |
(6.5)
| 1453 |
(14.7)
|
STI*† | 296 |
13.5
| 379 |
4.1
| 34 |
12.7
| 42 |
5.9
| 330 |
13.4
| 422 |
4.3
|
Maternal comorbidities‡ | 236 |
10.8
| 1022 |
11.3
| 53 |
20.0
| 184 |
26.3
| 289 |
11.7
| 1207 |
12.4
|
missing | 2 |
(0.1)
| 92 |
(1.0)
| 2 |
(0.8)
| 7 |
(1.0)
| 5 |
(0.2)
| 99 |
(1.0)
|
Chorioamnionitis* | 62 |
2.8
| 265 |
2.9
| 22 |
8.2
| 41 |
5.8
| 84 |
3.4
| 306 |
3.1
|
Meconium (moderate/heavy) | 198 |
9.0
| 510 |
5.6
| 6 |
2.3
| 19 |
2.7
| 204 |
8.3
| 530 |
5.4
|
missing | 4 |
(0.2)
| 98 |
(1.1)
| 20 |
(7.5)
| 26 |
(3.7)
| 25 |
(1.0)
| 126 |
(1.3)
|
BV exposed | BV unexposed | RR | 95 % CI | aRR | 95 % CI | |||
---|---|---|---|---|---|---|---|---|
N = 2198 | N = 9156 | |||||||
n
|
%
|
n
|
%
| |||||
Assisted ventilation at birth | 100 |
4.6
| 331 |
3.6
| 1.26 | 1.01–1.57 | 1.28 | 1.02–1.61 |
Admission to NICU at birth | 89 |
4.1
| 272 |
3.0
| 1.36 | 1.08–1.72 | 1.42 | 1.11–1.82 |
Neonatal sepsis | 48 |
2.2
| 126 |
1.4
| 1.59 | 1.14–2.21 | 1.60 | 1.13–2.27 |
Fetal Mortality | 3 |
0.1
| 13 |
0.1
| 0.96 | 0.27–3.37 | 1.15* | 0.27–4.96 |
Infant mortality | 4 |
0.2
| 24 |
0.3
| 0.69 | 0.24–2.00 | 0.39 | 0.12–1.28 |
BV exposed | BV unexposed | aRR | 95 % CI | |||
---|---|---|---|---|---|---|
N = 2198 | N = 9156 | |||||
n
|
%
|
n
|
%
| |||
Assisted ventilation at birth | 98 |
4.5
| 328 |
3.6
| 1.28 | 1.02–1.61 |
additionally adjusted for chorioamnionitis | 98 |
4.5
| 328 |
3.6
| 1.28 | 1.02–1.61 |
additionally adjusted for meconium | 98 |
4.5
| 328 |
3.7
| 1.22 | 0.97–1.53 |
Admission to NICU at birth | 88 |
4.1
| 269 |
3.0
| 1.42 | 1.11–1.82 |
additionally adjusted for chorioamnionitis | 88 |
4.1
| 269 |
3.0
| 1.45 | 1.13–1.85 |
additionally adjusted for meconium | 88 |
4.1
| 267 |
3.0
| 1.34 | 1.05–1.72 |
Neonatal sepsis | 48 |
2.2
| 125 |
1.4
| 1.60 | 1.13–2.27 |
additionally adjusted for chorioamnionitis | 48 |
2.2
| 125 |
1.4
| 1.67 | 1.19–2.35 |
additionally adjusted for meconium | 48 |
2.2
| 125 |
1.4
| 1.51 | 1.06–2.14 |
Fetal Mortality | 3 |
0.1
| 12 |
0.1
| 1.15* | 0.27–4.96 |
additionally adjusted for chorioamnionitis | 3 |
0.1
| 12 |
0.1
| 1.14* | 0.27–4.88 |
additionally adjusted for meconium | 0 |
0.0
| 3 |
0.0
| - | - |
Infant mortality | 3 |
0.1
| 24 |
0.3
| 0.39 | 0.12–1.28 |
additionally adjusted for chorioamnionitis | 3 |
0.1
| 24 |
0.3
| 0.39 | 0.12–1.27 |
additionally adjusted for meconium | 3 |
0.1
| 23 |
0.3
| 0.40 | 0.12–1.34 |
BV exposed | BV unexposed | RR | 95 % CI | aRR | 95 % CI | |||
---|---|---|---|---|---|---|---|---|
N = 267 | N = 708 | |||||||
n
|
%
|
n
|
%
| |||||
Assisted ventilation at birth | 51 |
19.1
| 94 |
13.3
| 1.44 | 1.05–1.96 | 1.23 | 0.89–1.73 |
Admission to NICU at birth | 124 |
50.4
| 246 |
36.0
| 1.40 | 1.20–1.64 | 1.24 | 1.04–1.46 |
Neonatal sepsis | 47 |
17.6
| 82 |
11.6
| 1.52 | 1.09–2.11 | 1.31 | 0.91–1.89 |
Fetal Mortality | 21 |
7.9
| 21 |
3.0
| 2.65 | 1.47–4.78 | 1.25 | 0.67–2.33 |
Infant mortality | 17 |
6.9
| 21 |
3.1
| 2.26 | 1.21–4.22 | 1.10 | 0.66–1.84 |
BV exposed | BV unexposed | RR | 95 % CI | aRR | 95 % CI | |||
---|---|---|---|---|---|---|---|---|
N = 2468 | N = 9872 | |||||||
n
|
%
|
n
|
%
| |||||
Preterm birth |
267
|
10.8
|
708
|
7.2
| 1.51 | 1.32–1.72 | 1.55 | 1.34–1.78 |
Assisted ventilation at birth | 151 |
6.1
| 425 |
4.3
| 1.42 | 1.19–1.70 | 1.45 | 1.21–1.75 |
Admission to NICU at birth | 213 |
8.7
| 519 |
5.3
| 1.65 | 1.42–1.92 | 1.73 | 1.47–2.03 |
Neonatal sepsis | 95 |
3.9
| 209 |
2.1
| 1.82 | 1.43–2.31 | 1.86 | 1.44–2.41 |
Fetal Mortality | 25 |
1.0
| 35 |
0.4
| 2.86 | 1.71–4.76 | 2.79* | 1.54–5.05 |
2nd trimester
| 16 |
0.7
| 7 |
0.1
| 12.22 | 4.29–34.79 | 10.42* | 3.55–30.61 |
3rd trimester
| 9 |
0.4
| 28 |
0.3
| 1.49 | 0.65–3.40 | 1.31* | 0.55–3.11 |
Infant mortality | 21 |
0.9
| 45 |
0.5
| 1.89 | 1.12–3.15 | 1.61 | 0.90–2.90 |