Cases | Controls | Percentage of missing | Complete records Single factor | Complete and imputed data Single factor Selected multivariate | |||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Variable | No | % | No | % | records | OR | 95% CI | OR* | 95% CI | AOR‡ | 95% CI |
Bed sharing No Yes | 1131 323 | 77.8 22.2 | 4192 446 | 90.4 9.6 | 0.9 | 1 2.6 | 2.2 to 3.1 | 1 2.6 | – 2.2 to 3.1 | 1 2.7‡ | – 1.4 to 5.3 |
Feeding Breast Bottle | 504 940 | 34.9 65.1 | 2491 2168 | 53.5 46.5 | 0.8 | 1 2.9 | – 2.5 to 3.3 | 1 2.9 | – 2.5 to 3.3 | 1 1.5 | – 1.2 to 1.8 |
Position last left Back all ages Side Front | 377 438 607 | 26.5 30.8 42.7 | 1972 1869 791 | 42.6 40.3 17.1 | 1.6 | 1 1.6 7.8 | – 1.3 to 1.8 6.4 to 9.5 | 1 1.6 7.9 | – 1.3 to 1.9 6.5 to 9.6 | 1 1.5† 10.5† | – 1.2 to 2.1 7.5 to 14.6 |
Parental smoking Neither Partner only Mother only Both | 314 194 194 703 | 22.4 13.8 13.8 50.0 | 2285 1083 427 774 | 50.0 23.7 9.4 16.9 | 2.9 | 1 1.4 3.7 7.4 | – 1.1 to 1.7 3.0 to 4.6 6.2 to 8.7 | 1 1.4 3.8 7.3 | – 1.1 to 1.7 3.1 to 4.7 6.2 to 8.6 | 1 1.1* 1.5* 2.9* | – 0.8 to 1.4 1.2 to 2.1 2.3 to 3.6 |
Mother took 2 unit or more of alcohol in last 24 h | 61.3 | ||||||||||
No Yes | 478 112 | 81.0 19.0 | 1694 99 | 94.5 5.5 | 1 5.1 | – 3.7 to 7.0 | 1 6.5 | – 4.6 to 9.3 | 1 4.8* | – 2.6 to 8.9 | |
Mother used illegal drugs after birth | 60.5 | ||||||||||
None Any | 582 21 | 96.5 3.5 | 1825 3 | 99.8 0.2 | 1 19.2 | – 5.4 to 68.3 | 1 30.7 | – 8.8 to 106.8 | 1 11.5* | – 2.2 to 59.5 | |
Sex Unmatched studies: Female Male | 351 538 | 39.5 60.5 | 1401 1442 | 49.3 50.7 | 0.3 | 1 1.5 | – 1.3 to 1.8 | 1 1.5 | – 1.3 to 1.7 | 1 1.6 | – 1.3 to 1.9 |
Matched studies: Female Male | 217 360 | 37.6 62.4 | 683 1141 | 37.5 62.5 | 1 1.0 | – 0.8 to 1.2 | 1 1.0 | – 0.8 to 1.2 | 1 0.8 | – 0.6 to 1.1 | |
Race White Non-white | 1181 276 | 81.1 18.9 | 4242 434 | 90.7 9.3 | 0.3 | 1 3.0 | – 2.5 to 3.6 | 1 3.0 | – 2.5 to 3.6 | 1 1.5 | – 1.1 to 1.9 |
Birth Weight group: 3500 g or more 2500 to 3499 g 2000 to 2499 g under 2000 g | 415 760 144 120 | 28.9 52.8 10.0 8.3 | 2293 2092 127 59 | 50.1 45.8 2.8 1.3 | 2.3 | 1 2.0 6.3 13.5 | – 1.7 to 2.3 4.8 to 8.2 9.6 to 18.9 | 1 2.0 6.4 13.8 | – 1.7 to 2.3 4.9 to 8.3 9.8 to 19.4 | 1 1.7 4.2 9.6 | – 1.4 to 2.0 2.9 to 6.0 6.2 to 14.7 |
Mother's age in years Over 30 26 to 30 21 to 25 19 to 20 18 under | 326 419 434 162 113 | 22.4 28.8 29.9 11.1 7.8 | 1921 1552 910 169 111 | 41.2 33.3 19.5 3.6 2.4 | 0.6 | 1 1.8 3.3 6.8 7.1 | – 1.5 to 2.1 2.8 to 3.9 5.2 to 8.8 5.3 to 9.6 | 1 1.8 3.3 6.8 7.2 | – 1.5 to 2.1 2.8 to 3.9 5.3 to 8.8 5.3 to 9.7 | 1 1.9 3.0 7.7 9.1 | – 1.5 to 2.3 2.4 to 3.8 5.2 to 11.4 5.9 to 14.1 |
Number of live births including the present one: | 0.8 | ||||||||||
1 2 3 4 5 or more | 407 491 280 149 122 | 28.1 33.9 19.3 10.3 8.4 | 1836 1566 748 304 200 | 39.4 33.7 16.1 6.5 4.3 | 1 1.4 1.8 2.6 3.5 | – 1.2 to 1.7 1.5 to 2.2 2.1 to 3.3 2.7 to 4.5 | 1 1.4 1.9 2.6 3.5 | – 1.2 to 1.7 1.5 to 2.2 2.1 to 3.3 2.7 to 4.6 | 1 2.3 3.8 5.2 7.7 | – 1.9 to 2.9 2.9 to 4.9 3.7 to 7.4 5.3 to 11.3 | |
Mother's marital status: Married or with partner Single | 996 467 | 68.1 31.9 | 4049 628 | 86.6 13.4 | 0.2 | 1 4.0 | – 3.4 to 4.7 | 1 4.0 | – 3.4 to 4.7 | 1 1.9 | – 1.5 to 2.4 |
Where slept last Parents' room Elsewhere | 817 617 | 56.9 43.1 | 2806 1823 | 60.6 39.4 | 1.4 | 1 1.3 | – 1.1 to 1.5 | 1 1.3 | – 1.2 to 1.5 | 1 2.4 | – 2.0 to 2.9 |
‡Multivariate AORs including AOR for bed sharing pooled for all ages up to 1 year. †Multivariate AOR when baby in a cot in parent's room & age is 3 months or less. The corresponding AOR's when baby is over 3 m are 1.4 (1.1 to 1.8) & 7.7 (5.9 to 10.2) respectively. *Multivariate AOR when baby in a cot in parents' room. AOR, Adjusted OR.