Smoking and the sudden infant death syndrome: results from 1993-5 case-control study for confidential inquiry into stillbirths and deaths in infancy. Confidential Enquiry into Stillbirths and Deaths Regional Coordinators and Researchers.
OBJECTIVE
To investigate the effects of exposure to tobacco smoke and of parental consumption of alcohol and illegal drugs as risk factors for the sudden infant death syndrome after a national risk reduction campaign which included advice on prenatal and postnatal avoidance of tobacco smoke.


METHODS
Two year population based case-control study. Parental interviews were conducted for each infant who died and four controls matched for age and date of interview.


METHODS
Three regions in England with a total population of 17 million people.


METHODS
195 babies who died and 780 matched controls.


RESULTS
More index than control mothers (62.6% v 25.1%) smoked during pregnancy (multivariate odds ratio = 2.10; 95% confidence interval 1.24 to 3.54). Paternal smoking had an additional independent effect when other factors were controlled for (2.50; 1.48 to 4.22). The risk of death rose with increasing postnatal exposure to tobacco smoke, which had an additive effect among those also exposed to maternal smoking during pregnancy (2.93; 1.56 to 5.48). The population attributable risk was over 61%, which implies that the numbers of deaths from the syndrome could be reduced by almost two third if parents did not smoke. Alcohol use was higher among index than control mothers but was strongly correlated with smoking and on multivariate analysis was not found to have any additional independent effect. Illegal drug use was more common among the index parents, and paternal use of illegal drugs remained significant in the multivariate model (4.68; 1.56 to 14.05).


CONCLUSIONS
This study confirms the increased risk of the sudden infant death syndrome associated with maternal smoking during pregnancy and shows evidence that household exposure to tobacco smoke has an independent additive effect. Parental drug misuse has an additional small but significant effect.
Blair
P S
PS
Foundation for the Study of Infant Deaths Research Unit, Royal Hospital for Sick Children, Bristol.
Fleming
P J
PJ
Bensley
D
D
Smith
I
I
Bacon
C
C
Taylor
E
E
Berry
J
J
Golding
J
J
Tripp
J
J
D000428:Alcohol Drinking; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D015999:Multivariate Analysis; D011247:Pregnancy; D011248:Pregnancy Complications / Q000209:etiology; D011297:Prenatal Exposure Delayed Effects; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects*; D019966:Substance-Related Disorders; D013398:Sudden Infant Death / Q000209:etiology*