Table 5.

Combined Effect of Position Placed to Sleep the Last Time and Prenatal and Maternal Risk Factors, and the Risk of SIDS

ModifierSleeping PositionSIDS (%)Controls (%)OR95% CITest for Additive Interaction*
Birth weight
 ≥2500 gSupine29 (14.9)362 (43.6)1ReferentP< .001, 2 df
Side59 (30.3)303 (36.5)2.71.6 –4.5
Prone107 (54.9)165 (19.9)11.66.8 –20
 <2500 gSupine2 (4.8)9 (39.1)1.40.29 –7.1
Side19 (45.2)9 (39.1)36.613 –107
Prone21 (50.0)5 (21.7)83.225 –276
Gestational age
 TermSupine25 (13.2)357 (44.2)1ReferentP= .002, 2 df
Side58 (30.5)296 (36.6)3.31.9 –5.9
Prone107 (56.3)155 (19.2)15.68.7 –28
 PretermSupine4 (9.1)12 (38.7)2.90.79 –10
Side19 (43.2)9 (29.0)40.514 –115
Prone21 (47.7)10 (32.3)48.819 –128
Intrauterine growth at term
 NormalSupine21 (13.8)332 (44.3)1ReferentP= .01, 2 df
Side41 (27.0)272 (36.3)2.61.4 –4.7
Prone90 (59.2)145 (19.4)13.67.5 –25
 Growth retardedSupine4 (10.5)25 (42.4)1.40.39 –4.7
Side17 (44.7)24 (40.7)9.64.3 –22
Prone17 (44.7)10 (16.9)38.814 –108
Any illness 1st week of life
 NoSupine27 (15.5)299 (43.6)1ReferentP= .02, 2 df
Side54 (31.0)253 (36.9)2.71.6 –4.7
Prone93 (53.4)133 (19.4)12.37.0 –22
 YesSupine4 (6.3)73 (43.7)0.620.20 –1.9
Side24 (38.1)57 (34.1)5.52.8 –11
Prone35 (55.6)37 (22.0)16.98.4 –34
Smoking in pregnancy
 NoSupine9 (9.9)258 (43.1)1ReferentP< .001, 2 df
Side23 (25.3)219 (36.6)2.91.3 –6.7
Prone59 (64.8)122 (20.4)16.77.6 –37
 YesSupine22 (15.1)114 (45.4)4.92.1 –11
Side54 (37.0)89 (35.5)16.57.4 –37
Prone70 (47.9)48 (19.1)55.324 –127
Maternal age (y)
 ≥25Supine19 (11.2)310 (43.7)1ReferentP= .10, 2 df
Side52 (30.8)261 (36.8)3.62.0 –6.6
Prone98 (58.0)138 (19.5)17.99.6 –33
 <25Supine12 (17.4)64 (43.5)3.01.3 –6.9
Side26 (37.7)51 (34.7)11.05.2 –23
Prone31 (44.9)32 (21.8)28.713 –64
Birth order
 FirstSupine10 (18.5)164 (47.4)1ReferentP= .05, 2 df
Side25 (46.3)125 (36.1)4.11.7 –9.5
Prone19 (35.2)57 (16.5)10.34.0 –26
 Second or higherSupine21 (11.4)209 (41.1)1.80.79 –4.1
Side53 (28.8)187 (36.8)5.52.5 –12
Prone110 (59.8)112 (22.0)23.111 –51
Maternal education (y)
 ≥10Supine23 (14.6)339 (46.3)1ReferentP= .003, 2 df
Side48 (30.4)242 (33.1)3.82.1 –6.9
Prone87 (55.1)151 (20.6)13.77.6 –25
 <10Supine8 (10.4)33 (28.9)4.61.7 –12
Side28 (36.4)63 (55.3)8.44.1 –17
Prone41 (53.2)18 (15.8)55.224 –128
Marital status at birth
 Married/cohabitantSupine30 (14.2)364 (44.2)1ReferentP= .01, 2 df
Side68 (32.1)298 (36.0)3.21.9 –5.3
Prone114 (53.8)163 (19.8)12.77.4 –22
 SingleSupine1 (3.8)10 (31.3)0.970.11 –8.3
Side10 (38.5)15 (46.9)7.22.8 –18
Prone15 (57.7)7 (21.9)56.018 –176
  • * Test for interaction in conditional logistic regression with additive relative risk model (EGRET).

  • Term infants with birth weight <10 percentile (2967 g).