How reliable is reported sleeping position in cases of unexpected infant death?

Examination of sudden infant death syndrome (SIDS) deaths in South Australia over a 7-year period from 2000 to 2006 was undertaken. There were 32 out of 35 cases where details of position when found were known. The data confirmed a marked decline in deaths in the prone position over the past decade, but showed no significant decline in cases reportedly found dead in the supine position. Posterior lividity was present in most cases (n = 30), 10 of whom also had anterior lividity. Posterior lividity was attributable either to the position of the body after death or to the effect of supine postmortem storage. In six cases, however, fixed anterior lividity indicated that death had occurred in the prone position despite statements that the infants had been found on the side (n = 1) and in the supine position (n = 5). This contradiction indicates that caregivers' descriptions of terminal sleeping positions may not be supported by autopsy findings. The numbers of SIDS deaths reported in the supine position in South Australia may not, therefore, represent a genuine tally, but instead may be a function of inaccurate reporting. This may act as a confounding factor in studies attempting to link sleeping position with other risk factors.