The Linked BirthInfant Death Data Set TJ Mathews

The Linked Birth/Infant Death Data Set TJ Mathews Thanks to Joyce Martin, Stephanie Ventura, Marian Mac. Dorman, and Paul Sutton NCHS Data Users Conference July 10 -12, 2006 Washington, DC

The Revised Death Certificate

Important items from Main Mortality File Characteristics of the decedent Age Race Hispanic origin Sex Cause of Death

The Revised Birth Certificate

Important items from Birth File Birthweight Period of gestation Age Marital Status Education Maternal medical and other risk factors

Race and Ethnicity reporting The linked file uses the race and ethnicity as self reported by the mother on the birth certificate. The race and ethnicity from the main mortality file is reported by others for the decedent. These different reporting methods can lead to different race/ethnicity specific infant mortality rates between the two files.

Birth Certificate checkbox items add many variables to the Linked file Tobacco Use Weight Gain Obstetric Procedures Complications of Labor

Geographic suppression is used to protect confidentiality Only Cities and Counties with populations over 250, 000 are identified in the data set.

Cohort File – data based on all deaths to infants born in a given year 2002 Cohort File = 2002 births, 2002 and 2003 deaths

Period File – data based on all infant deaths in a given year 2003 Period File = 2003 deaths, 2002 and 2003 births

Creating the Linked file Birth Certificate Hospital (99% of US births) State Vital Statistics Office NCHS File and Publication Production

Timing and Dissemination of data First linked data in 1985 No files for 1992 -1994 Period linked file began in 1995 2002 Cohort and 2004 Period file now in process

Linked file data available on CD ROM Cohort file – 1985 -91 and 1995 -2001 Period file available on the Perinatal CD ROM – 1995 -2002 Period file for 2003 (with revised format) now available in ASCII

Infant Mortality Rate by Race and Ethnicity of Mother, 2003 Total U. S. Note: Rates are per 1, 000 live births. Source: NCHS/CDC/National Vital Statistics System

Birthweight Breakout for Births and Infant Deaths, 2003 Source: NCHS/CDC/National Vital Statistics System

Gestation Breakout for Births and Infant Deaths, 2003 Source: NCHS/CDC/National Vital Statistics System

Infant Mortality Rates by State, 20012003 Source: NCHS/CDC/National Vital Statistics System

Infant Mortality Rate: United States, 1990 -2003 Overall decline 26% Source: NCHS/CDC/National Vital Statistics System

Research from the 2002 Linked Birth/Infant Death File The US infant mortality rate increased in 2002, the first increase since 1958. NCHS researchers, using the linked birth/infant death files, were able to determine the primary reason for the increase. The number of infants <750 grams increased. These infants are at high risk of infant death. In 2003 the rate returned to that observed in 2001. Source: NCHS/CDC/National Vital Statistics System

A more refined Infant Mortality Rate To improve sensitivity and precision the infant mortality rate is now published with two decimal places. Rates by cause of death which are per 100, 000 continue to show one decimal. The overall rate in 2003 was 6. 84 per 1, 000 live births. Source: NCHS/CDC/National Vital Statistics System