THURSDAY, Aug. 4 (HealthDay News) -- The autopsy rate in the United States has declined from about one in five to one in 10 Americans from 1972 to 2007, according to a new federal study.

This accounts for a 58 percent drop between 1972 and 2007, from 19.3 percent to 8.5 percent of deaths, the researchers noted.

In 1972, deaths due to disease accounted for 79 percent of autopsies, while deaths due to external causes such as injury or murder accounted for 19 percent. By 2007, the respective percentages were 46 percent and 50 percent, the investigators found.

External causes of death -- including murder, accidental injury, suicide or undetermined cause -- accounted for nine of the 10 most frequently autopsied causes of death in 2007.

In 2007, autopsy rates declined with age, from 60 percent of deaths of people aged 15 to 24, 55.8 percent at ages 25 to 34, 11 percent at ages 55 to 64, and 4.2 percent at ages 65 to 74, according to the study by the National Center for Health Statistics at the U.S. Centers for Disease Control and Prevention.

The study also reported that while the number of deaths among older people increased from 1972 to 2007, autopsied deaths were increasingly concentrated in the 1 to 34 and 35 to 64 age groups.

Even though 91 percent of deaths in the United States in 2007 were caused by disease, death due to complications of pregnancy, childbirth and puerperium (the state of a woman during and up to six weeks after childbirth) was the only grouped disease condition among the 10 most frequently autopsied causes of death.

Just over half of deaths due to complications of pregnancy, childbirth and puerperium were autopsied in 2007.

Reasons for the changing autopsy rates are not entirely clear, but may be related to hospital accreditation standards, state laws about which deaths should be investigated and regulations created since 1972 about investigating infant deaths, according to the report.

More information

The American Academy of Family Physicians has more about autopsy.