Brain weight-body weight ratio in sudden infant death syndrome revisited.

Aims: To determine whether the brain-body weight ratio is increased in sudden infant death syndrome (SIDS).

Methods: Review of autopsy files from Forensic Science SA, South Australia was undertaken over an eight-year period from 1999 to 2006, with classification of cases according to the San Diego definition. Sudden and/or unexpected deaths in previously healthy infants due to asphyxia or infection were selected as controls.

Results: There were 42 SIDS cases and 25 controls. The SIDS cases were aged from 1 to 42 weeks (mean: 16.26 ± 1.5 weeks) with a male to female ratio of 26:16. The control infants were aged from 3 to 48 weeks (mean: 19.24 ± 2.9 weeks) (P > 0.05) (M:F = 16:9) and included 13 cases of asphyxia and 12 cases of sepsis. Comparison of the brain-body weight ratios failed to demonstrate a significant difference: SIDS mean = 0.121 ± 0.003; control mean = 0.115 ± 0.003 (P > 0.05).

Conclusion: Although, there was a trend towards higher brain-body weight ratios in SIDS infants, this did not reach significance. The role of brain weight in the aetiology of SIDS remains controversial.