To examine cause-of-death terminology written on death certificates for sudden infant death syndrome (SIDS) and to determine the adequacy of this text data in more fully describing circumstances potentially contributing to SIDS deaths.

With 2003 and 2004 US mortality files, we analyzed all deaths that were assigned the underlying cause-of-death code for SIDS (R95). With the terminology written on the death certificates, we grouped cases into SIDS-related cause-of-death subcategories and then assessed the percentage of cases in each subcategory with contributory or possibly causal factors described on the certificate.

Of the 4408 SIDS-coded deaths, we subcategorized 67.2% as “SIDS” and 11.0% as “sudden unexplained (or unexpected) infant death.” The terms “probable SIDS” (2.8%) and “consistent with SIDS” (4.6%) were found less frequently. Of those death certificates that described additional factors, “bedsharing or unsafe sleep environment” was mentioned approximately 80% of the time. Most records (79.4%) did not mention any additional factors.

Our death certificate analysis of the cause-of-death terminology provided a unique opportunity to more accurately characterize SIDS-coded deaths. However, the death certificate was still limited in its ability to more fully describe the circumstances leading to SIDS death, indicating the need for a more comprehensive source of SIDS data, such as a case registry.