Risk factors
|
RDS 32–36 weeks
|
RDS 37–38 weeks
|
---|
Cases
|
Fetuses at risk
|
Rate/1000a
|
Odds ratiosb [95 % CI]
|
Cases
|
Fetuses at risk
|
Rate/1000a
|
Odds ratiosb [95 % CI]
|
---|
Age
|
<20 years
|
1165
|
426,327
|
2.7
|
1.00 [0.94, 1.06]
|
360
|
386,323
|
0.93
|
0.83 [0.74, 0.92]
|
20–34
|
8969
|
3,265,775
|
2.7
|
Reference
|
3364
|
2,978,793
|
1.13
|
Reference
|
≥35
|
1808
|
610,342
|
3.0
|
1.03 [1.01, 1.04]
|
568
|
545,748
|
1.04
|
0.97 [0.95, 1.00]
|
Multi-fetal gestation
|
2770
|
133,526
|
20.7
|
9.61 [9.21, 10.0]
|
214
|
55,869
|
3.83
|
3.63 [3.16, 4.17]
|
Smoking
|
1613
|
441,604
|
3.7
|
1.37 [1.30, 1.44]
|
632
|
392,595
|
1.61
|
1.55 [1.42, 1.69]
|
Diabetes mellitus
|
996
|
160,801
|
6.2
|
2.35 [2.20, 2.51]
|
414
|
136,882
|
3.02
|
2.95 [2.67, 3.27]
|
Chronic hypertension
|
423
|
44,759
|
9.5
|
3.52 [3.19, 3.88]
|
126
|
35,036
|
3.60
|
3.35 [2.81, 4.01]
|
Congenital anomaly
|
832
|
61,034
|
13.6
|
5.26 [4.90, 5.65]
|
346
|
50,707
|
6.82
|
6.71 [6.01, 7.50]
|
Male sex
|
7130
|
2,200,877
|
3.2
|
1.42 [1.37, 1.47]
|
2739
|
1,994,128
|
1.37
|
1.70 [1.59, 1.81]
|
All
|
11,942
|
4,302,444
|
2.8
|
-
|
4292
|
3,910,864
|
1.10
|
-
|
-
aRates of RDS <32 weeks represent cumulative incidence from 24 to 31 weeks (8 week period) and cannot be directly compared with rates of RDS ≥39 weeks which represent cumulative incidence from 39 to 43 weeks (5 week period)
-
bOdds ratios were estimated by contrasting the RDS rate among those with and those without the risk factor e.g., RDS < 32 weeks among infants of smokers vs nonsmokers. Since odds ratios express the relative effect of risk factors on RDS, the odds ratios for early gestation RDS can be directly compared with the odds ratios for late gestation RDS