TABLE 3

SIDS Risk Factors by Age Groupa

Pre-BTS 1991–1993BTS Era 1996–2008
<2 mo2–4 mo≥5 moP Value<2 mo2–4 mo≥5 moP Value
No. of SIDS cases38111208017354
Twin or triplet1 (2.7%)7 (6.9%)1 (5.3%).641 (1.3%)14 (8.4%)1 (2.0%).04
Ever breastfed8 (72.7%)41 (82.0%)3 (75.0%).7652 (88.1%)80 (77.7%)23 (65.7%).04
Breastfed at time of death6 (16.7%)18 (17.5%)2 (11.8%).8432 (41.0%)32 (19.6%)9 (18.4%)<.001
Sleep siteb.48<.001
 Crib, toddler bed, stroller lying flat19 (50.0%)68 (62.4%)13 (65.0%)14 (17.7%)80 (46.2%)18 (33.3%)
 Adult bed11 (29.0%)24 (22.0%)4 (20.0%)50 (63.3%)62 (35.8%)27 (50.0%)
 Couch, recliner, other soft chair5 (13.2%)6 (5.5%)1 (5.0%)7 (8.9%)9 (5.2%)2 (3.7%)
 Waterbed or inflatable bed0 (0.0%)3 (2.8%)0 (0.0%)0 (0.0%)0 (0.0%)0 (0.0%)
 Car seat, car bed, bouncy chair0 (0.0%)2 (1.8%)1 (5.0%)4 (5.1%)9 (5.2%)1 (1.9%)
 Floor, possibly on pillow or blanket1 (2.6%)3 (2.8%)0 (0.0%)1 (1.3%)8 (4.6%)2 (3.7%)
 Playpen1 (2.6%)2 (1.8%)0 (0.0%)2 (2.5%)5 (2.9%)3 (5.6%)
 Being held, breastfeeding, in a sling1 (2.6%)1 (0.9%)1 (5.0%)1 (1.3%)0 (0.0%)0 (0.0%)
 Other0 (0.0%)0 (0.0%)0 (0.0%)0 (0.0%)0 (0.0%)1 (1.9%)
 Unknownc020100
Sleep position foundd.66.08
 Prone26 (81.3%)74 (87.1%)10 (71.4%)23 (33.8%)84 (53.9%)25 (52.1%)
 Side2 (6.3%)6 (7.1%)1 (7.1%)14 (20.6%)26 (16.7%)7 (14.6%)
 Supine3 (9.4%)4 (4.7%)2 (14.3%)27 (39.7%)37 (23.7%)15 (31.3%)
 Car seat/bouncy seat0 (0.0%)1 (1.2%)1 (7.1%)4 (5.9%)9 (5.8%)1 (2.1%)
 Being held1 (3.1%)0 (0.0%)0 (0.0%)0 (0.0%)0 (0.0%)0 (0.0%)
 Unknownc626612176
Face position.19.03
 Down13 (56.5%)25 (37.9%)9 (60.0%)12 (20.0%)54 (39.7%)12 (34.3%)
 Side9 (39.1%)37 (56.1%)4 (26.7%)35 (58.3%)55 (40.5%)12 (34.3%)
 Up1 (4.4%)4 (6.1%)2 (13.3%)13 (21.7%)27 (19.9%)11 (31.4%)
 Unknownc15455203719
Face obstructed2 (6.1%)7 (6.5%)3 (15.8%).351 (1.4%)9 (5.6%)6 (13.3%).02
Bed-sharing11 (29.0%)19 (17.4%)2 (10.0%).1651 (63.8%)48 (28.7%)15 (27.8%)<.001
No. of known intrinsic risk factors1.3 ± 1.01.3 ± 1.01.7 ± 1.2.321.3 ± 0.91.5 ± 1.01.1 ± 0.9.09
 ≥1 intrinsic risk factor29 (76.3%)87 (78.4%)18 (90.0%).4469 (86.3%)149 (86.1%)42 (77.8%).30
 ≥2 intrinsic risk factors14 (36.8%)43 (38.7%)9 (45.0%).8329 (36.3%)65 (37.6%)16 (29.6%).57
No. of known extrinsic risk factors2.3 ± 1.12.1 ± 1.42.0 ± 1.4.452.3 ± 1.22.0 ± 1.32.0 ± 1.3.23
 ≥1 extrinsic risk factor38 (100.0%)100 (90.1%)17 (85.0%).08274 (92.5%)152 (87.9%)48 (88.9%).54
 ≥2 extrinsic risk factors28 (73.7%)69 (62.2%)12 (60.0%).4063 (78.8%)114 (65.9%)34 (63.0%).07
  • a Continuous variables are summarized as mean ± SD and analyzed with analysis of variance; categorical variables are presented as n (%) and analyzed with χ2 tests. P values reflect differences between age groups within time period. Some risk factors contain missing data. The following risk factors showed no difference by age group and are therefore not included in the table: gender, race, death in winter, prematurity, maternal smoking, alcohol use, and drug use, URTI, and bed-sharing with other children.

  • b Because of the inadequate sample size of most categories, the P value reflects a test of crib/bassinet/toddler bed/stroller lying flat versus adult bed. A toddler bed uses a crib mattress.

  • c The category “unknown” was excluded from statistical comparisons. It is presented only for completeness of data.

  • d Because of the inadequate sample size of some categories, the P value reflects a test of prone versus side versus supine.