1000 B.C. In Egypt, women found to have accidentally smothered a baby as they slept together are condemned to hold the dead infant for three days as punishment.

600 B.C. In the Bibles First Book of Kings, the prophet Jeremiah tells of how King Solomon settles a dispute between two women over custody of a baby boy after the other one had lost her baby when she laid on him in her sleep.

1800s After centuries of alternating suspicion that parents either accidentally or deliberately stifled their babies in their sleep and sympathy for the seemingly mysterious deaths of healthy infants, a few doctors in Britain and the United States attempt to record patterns in infant deaths.

Circa 1900 A small group of doctors begin to suspect that some breathing defect kills many infants, but most babies with no apparent illness are still presumed to have suffocated.

1934 Dr. Sidney Farber publishes a report on fulminating streptococcus infections in infancy as a cause of sudden death in The New England Journal of Medicine, the first major medical journal report to suggest an alternative cause to suffocation.

1944 Dr. Harold Abramson in New York City analyzes infant deaths attributed to accidental mechanical suffocation in the previous four years, and finds 68 percent were sleeping on their stomachs and almost half were discovered with their nose and mouth in contact with bedding.

1947-1953 Drs. Jacob Werne and Irene Garrow, pathologists in Queens, N.Y., publish a refutation of Abramsons findings, saying claims of accidental suffocation increased the feeling of culpable negligence experienced by the mother. They find possible medical causes, mainly related to infections, for most deaths previously blamed on suffocation.

1949 Parents who have lost infants to sudden death press the Childrens Bureau of the National Institutes of Health to fund a conference on the topic in Washington, chaired by Farber.

1956 Dr. Lester Adelson, a pathologist who was deputy coroner for Cuyahoga County (Cleveland), Ohio, working under a contract from the Childrens Bureau, reports on autopsies of 126 infants, finding that in the majority of infants and children who die suddenly and unexpectedly there is an inflammatory process in some portion of the respiratory tract.

1962-68 Families of sudden infant death victims in several cities organize The Guild for Infant Survival and the National SIDS Foundation, to support other grieving parents and to back research.

1963 The first international conference on causes of sudden infant death is held in Seattle, and experts suggest labeling the cause a syndrome that implies a constellation of possible causes.

1967 Dr. Marie Valdes-Dapena, a pathologist at St. Christophers Childrens Hospital in Philadelphia, publishes a landmark paper that downplays the risk of suffocation by bed clothing, and examines various possible physical causes, while noting great numbers of these deaths remain inexplicable.

1969 During a second international conference, the term SIDS is formally coined and defined as the sudden death of an infant or young child that is unexpected by history and in which a thorough postmortem examination fails to demonstrate an adequate cause of death.

1970 The Guild for Infant Survival surveys chief medical officers of each state and finds that 16 different names were used for SIDS, that no uniform classification system exists for reporting SIDS deaths nationally, and that as a result, only 1,155 cases were reported in 1970, about a tenth the number researchers thought were actually dying.

1969-1973 Parental groups put increasing pressure on the NIH to fund more research and on Congress to hold hearings on SIDS.

1974 Congress passes the Sudden Infant Death Syndrome Act, which assigns research responsibility to the National Institute of Child Health and Human Development, and the Maternal and Child Health Bureau to set up educational and counseling programs about SIDS.

1979 The World Health Organization formally recognizes SIDS as a cause of death.

1980s By the end of the decade, the federal government has devoted tens of millions of dollars to SIDS research, and a growing database of results based on infant autopsies and other research suggests congenital defects may be responsible for many of the deaths.

1992-94 Extensive international research finds that babies who sleep on their stomachs are at significantly increased risk from SIDS. U.S. agencies, medical groups and parent-advocates launch the Back to Sleep campaign encouraging all new parents to have the infants sleep on their backs exclusively during the first six months of life.

1995 SIDS Network launched as an online information site for SIDS. A number of new SIDS support and educational groups spring up in the next decade, linked by the Web.

1996 The federal Centers for Disease Control and Prevention issues national guidelines for the investigation of sudden unexplained infant deaths. Standard autopsy and death scene investigation forms are published.

1998 By some estimates, the back sleeping program reduces SIDS deaths by 30 percent to 50 percent. But the overall number of unexplained infant deaths begins to level off, even as the SIDS death rate declines, prompting many experts to wonder if stricter investigative guidelines are code-shifting the causes of infant deaths.

2001 More infant deaths are being classified as unexplained or undetermined because investigators are finding evidence that doesnt allow for a SIDS diagnosis. In many jurisdictions investigators are finding that many infants are dying in adult beds or on soft bedding.

2005 The American Academy of Pediatrics issues a new policy on SIDS that recognizes shifts in coding and additional risks from infants sleep environments, including the need to avoid soft bedding, the hazards of adults sleeping with an infant, and the need to reinforce the back-to-sleep message to all caregivers. The SIDS Alliance begins spreading similar messages.

2006 Concerned about the quality of data on infant deaths, the CDC releases the new Sudden, Unexplained Infant Death Investigation Reporting Form and begins efforts to train and encourage investigators and death certifiers to collect more accurate data.