Serious Mental Illness in Parents Significantly Increases Infants' Risk for SIDS
By Pam Harrison
Medscape Medical News
January 11, 2010 — The risk for sudden infant death syndrome (SIDS) among infants born to parents who have received psychiatric inpatient care is significantly higher than in the general population. The risk is especially high if both parents have been admitted for any psychiatric reason or if the mother or both parents have been diagnosed as having an alcohol or drug disorder, new research suggests.
Roger Webb, MD, PhD, University of Manchester, England, and colleagues, report that of approximately 2.5 million live births recorded in Sweden between 1978 and 2004, the risk for SIDS was almost 7 times higher than in the general population if both parents had a history of any mental illness requiring hospital admission.
It was also almost 7 times higher than the general population if the mother had an alcohol or drug disorder, and it was more than 9 times higher than in the general population if both parents had an alcohol or drug disorder.
The risk for SIDS among infants was also 2-fold higher than in the general population if either the mother or the father had a history of hospital admission for any psychiatric illness other than an alcohol or drug disorder.
"Regardless of what group we are looking at, SIDS is a rare outcome so it’s important to recognize this, but clearly these families require greater levels of support than other families, and part of this is talking to these women about standard risk factors for SIDS, particularly stopping smoking during pregnancy, which we really need to encourage these women to do," Dr. Webb told Medscape Psychiatry.
The study is published in the January issue of Archives of General Psychiatry.
Relative SIDS Risk
For the study, investigators estimated the relative risk for SIDS in parents with a history of psychiatric inpatient care vs the general population and compared the prevalence of risk factors in infants with and without a parental psychiatric inpatient history.
They also explored how the Swedish risk reduction campaign against SIDS, introduced in 1992, modified risk factors for SIDS. The 27-year birth cohort was then categorized into 2 periods — 1978 through 1991 and 1992 through 2004.
A total of 1531 SIDS cases occurred in the whole cohort at a rate of 0.6 per 1000 live births. Furthermore, in 11.2% of all cases there had been at least 1 parental psychiatric inpatient admission before the birth, with almost half of this group having been admitted for alcohol or drug disorders, the study authors report.
Specifically, 118 instances of SIDS occurred in association with maternal admission histories and 82 episodes with paternal admission histories. The risk for SIDS was also highest among infants whose mothers were admitted with an alcohol or drug disorder if the last admission was within a year of the birth of the infant and lowest if it was 5 or more years previously.
In contrast, the risk for SIDS was higher among infants whose mothers were admitted for other types of psychiatric illnesses 5 or more years before the birth of the child.
Table. Odds Ratios for SIDS Stratified by Number of Years Since Last Maternal Psychiatric Inpatient Episode Before Birth
Diagnostic Group and Years Since Last Inpatient Episode No. of Deaths Risk per 1000 Live Births Adjusted OR (95% CI)
Admitted with any diagnosis ? ? ?
<1 12 1.8 3.3 (1.9 – 5.8)
1 – 4 46 1.8 3.1 (2.3 – 4.1)
?5 60 1.6 3.1 (2.4 – 4.1)
Alcohol or drug disorders ? ? ?
<1 8 5.2 9.0 (4.5 – 18.1)
1 – 4 25 3.6 6.9 (4.6 – 10.2)
?5 16 2.6 5.4 (3.3 – 8.8)
All diagnoses other than alcohol or drug disorders ? ? ?
<1 4 0.8 1.4 (0.5 – 3.9)
1 – 4 21 1.1 1.8 (1.2 – 2.8)
?5 44 1.4 2.7 (2.0 – 3.7)
CI = confidence interval; OR = odds ratio; SIDS = sudden infant death syndrome.
Modifiable Risk Factors
As investigators point out, known modifiable risk factors for SIDS include maternal smoking and the infant’s sleeping position. National risk reduction campaigns for the prevention of SIDS have successfully targeted these factors in the general population, where maternal smoking rates decreased by almost half.
However, the campaign had a much smaller effect on rates of maternal smoking among the highest-risk groups, where more than half of mothers with an alcohol- or drug-related admission still smoked antenatally after the campaign.
Indeed, "among infants with any parental psychiatric admission history (mother, father, or both parents), the relative risk [for SIDS] increased significantly after the campaign," the study authors write, a reflection of the risk reduction campaign not working as well in the at-risk population relative to the general population.
"In these particular groups of patients, a lot of problems coalesce, and if a family is experiencing a whole range of intractable social difficulties, it may be very difficult for women to stop smoking or to put the baby to sleep on their back because babies don’t sleep as well on their backs and this can be very stressful,” said Dr. Webb "So there are wider messages for health promotion for these families, and I think a key thing is better communication between medicine and other public health services."
Maternal Depression and SIDS
Peter Blair, PhD, University of Bristol, United Kingdom, told Medscape Psychiatry that previous work looking at maternal depression and increased SIDS risk has shown a link.
"On the surface, this study shows a significantly strong link between parents with mental health illnesses and SIDS, the risk being even higher when both parents have mental health issues, which suggests there is a biological gradient," he said.
However, as with all large cohort studies, "you have only so much detail and the mechanism by which mental health illness is causing an increase in SIDS risk is difficult to identify."
For example, the risk for SIDS among infants born to parents with alcohol and drug disorders seems to be highest, but the study is not able to tease out whether this risk is attributable to infant care practices in general, including whether the infant was correctly placed on its back while sleeping, or the alcohol and drug disorder per se, said Dr. Blair.
"I think it’s right that investigators reported these findings and what they have done they have done correctly, but you are standing too far away from the problem in studies like these to know for sure," he said.
Dr. Blair nevertheless agrees with the study authors’ conclusion that parents with mental health and alcohol or drug disorders should be targeted for special intervention so that they are more likely to adhere to preventive measures such as antenatal smoking cessation.
The project was funded by a grant from both the Wellcome Trust and the Foundation for the Study of Infant Deaths. The authors have disclosed no relevant financial relationships.
