Data Release Policy for Vital Statistics Micro-data Files
Over the years, confidentiality standards have changed for the public release of certain details on vital statistics micro-data files. Given these changes to confidentiality requirements, specific geographic and date information found in micro-data files will vary depending on the year in which the files were released.
The National Center for Health Statistics (NCHS) revised its policy on the release of and access to vital statistics micro-data effective with the 2005 data year. This document outlines the current NCHS/Division of Vital Statistics (DVS) policy on micro-data for births, deaths, fetal deaths, linked birth/infant death, and matched multiple births.
This revised policy is consistent with CDC and NCHS goals to make data available as widely as possible while protecting respondent confidentiality, assuring data quality, and conforming to state laws and regulations around vital statistics data.
Access to Micro-data
Micro-data refers to records for individual cases. Micro-data files released by DVS may include a single record for each birth or death.
Researchers who require exact dates or geographic information that is not available in the public-use files or through CDC WONDER may request access to restricted-use files from NCHS through the process outlined on the restricted-use vital statistics data page or request access to the data through the NCHS Research Data Center.
In exceptional cases involving critical issues related to public health surveillance, the DVS Director may provide data that have not yet been publicly released to certain federal agencies following direct submission of a written request.
Release of Micro-data
Final public-use and restricted-use micro-data files are typically released on the following schedules:
- Birth files: 7-8 months after the end of a data year; for example, the 2018 files were released in July 2019
- Death (multiple-cause) files: 11-12 months after the end of a data year; for example, the 2017 files were released in December 2018
- Fetal death files: 12 months after the end of the data year
- Period linked birth/infant death files: 8 months after the release of the death files for a data year
Web-based Systems for Constructing Your Own Tabulations
Public-use interactive web-based systems like WONDER (Wide-ranging ON-line Data for Epidemiological Research) and WISQARS (Web-based Injury Statistics Query and Reporting System) allow users to access data and construct their own tabulations.
Some of these interactive systems allow users to build tables based on micro-data; however, only tabulated data are presented to the user. Users can construct their own tabulations of births and deaths with geographic detail subject to population and/or cell size limitations. CDC WONDER includes more geographic detail than the downloadable public-use files.
Confidentiality Changes in Micro-data Files
All public-use micro-data files from 2005-present contain individual-level vital event data at the national level only. Specifically, these files contain no geographic identifiers at the state, county, or city level. They do not contain exact dates, but information on year, month, and day of week (e.g. Monday) are available. These files will generally include most other items and detail from the vital record. Items may vary from year to year.
Files released prior to 2005 may contain exact dates or geographic identifiers, as follows:
- Birth, death, and fetal death files
- 1988 and before: Birth, death, and fetal death public-use micro-data files contain geographic identifiers for all counties. Exact dates (year, month, and day) of birth and death are included.
- 1989-2004: Birth, death and fetal death public-use micro-data files contain geographic identifiers only for counties and cities with a population of 100,000 or greater. They do not contain exact dates, but information on year, month, and day of week (e.g. Monday) are available.
- Linked birth/infant death files
- 2004 and before: Linked birth/infant death public-use micro-data files contain geographic identifiers only for counties and cities with 250,000 or greater population. They do not contain exact dates, but information on year, month, and day of week (e.g. Monday) are available.
- Matched multiple birth files
The Matched Multiple Birth file combines data from the six years 1995 to 2000 but excludes all geographic identifiers and exact dates of births and deaths. The file also excludes year, month and day of week (e.g. Monday). The Matched Multiple Birth file for 1995-2000 and an earlier version for 1995-98 are available for downloading.
Availability of Geographic and Date Details in Public-Use Micro-data Files
|File||Year||State||County||City||Exact date of vital event (year, month, and day)|
|Birth, Death (multiple-cause), and Fetal Death||1988 and before||Yes||All||All||Yes|
|1989-2004||Yes||Population size ≥ 100,000||Population size ≥ 100,000||Year, month and day of the week|
|2005-latest||No||No||No||Year, month and day of the week|
|Linked birth/infant death (period or cohort)||2004 and before||Yes||Population size ≥ 250,000||Population size ≥ 250,000||Year, month and day of the week|
|2005 and after||No||No||No||Year, month and day of the week|
|Matched multiple birth||1995-2000||No||No||No||No|
Restricted-Use Micro-data Files
Restricted-use micro-data files contain dates and specific geographic information not available in the public-use files. Researchers interested in applying for access to these files can find detailed information on the restricted-use vital statistics data page.
The following files and variables are available under restricted conditions:
- All counties identified:
Researchers may request micro-data files (birth, death, fetal death, and linked birth/infant death) and compressed files (death only) containing geographic detail for all states and counties for those data years with limited (1989-2004) or no (2005 forward) geographic detail in the public-use files. NCHS will evaluate the research request. If approved, the applicant will have access to the files upon submission of a signed NCHS Data Use Agreement.
- Exact dates of vital events:
Researchers in federal agencies, as well as their on-site contractors, can submit project proposals that request exact dates of vital events. If needed, the file with the exact dates can also include geographic detail.Non-federal researchers (including federal grantees) can gain controlled access to exact dates of vital event files only through the NCHS Research Data Center after NCHS approval.
- Matched Multiple Birth file:
The Matched Multiple Birth file with all states and counties or exact dates included is accessible only through the NCHS Research Data Center. See the NCHS Research Data Center for specific procedures.
- Other files available under restricted conditions:
Restricted-use birth files for 1960, 1961, and 1967 are available from the NCHS Research Data Center upon special request and approval.
Different than a micro-data file, “compressed” data files do not contain as much detail as single-record micro-data files. A compressed data file is created by replacing groups of identical records with a single record and the number of times that record occurs in the file. This reduces the total number of records in the file. Compressed mortality data files produced by NCHS use broad age groupings and list only the following information: year and county of death, race, cause of death, and sex. They are available only for data years 2016 and prior.
More information about and access to public-use files is available from the compressed mortality file page. Note that specific geographic information is restricted on the 1989 to 2016 compressed mortality data files. Researchers may find more information about applying for access to these restricted files on the restricted-use vital statistics data page.
Availability of restricted-use files and of geographic and date details per file
|File||Year||State||County||City||Exact date of vital event (year, month, and day)*|
|Microdata:||Birth – Limited Geography||1989-latest||Yes||Population size ≥ 100,000||Population size ≥ 100,000||Year, month and day of the week|
|Death – Limited Geography||2005-latest||Yes||No||No||Year, month and day of the week|
|Birth – All Counties and Death – All Counties||1989-latest||Yes||All||Population size ≥ 100,000||Year, month and day of the week|
|Fetal death – All Counties||1989-latest||Yes||All||Population size ≥ 250,000||Year, month and day of the week|
|Period-linked birth/infant death – All Counties||1995-latest||Yes||All||Population size ≥ 250,000||Year, month and day of the week|
|Cohort-linked birth/infant death – All Counties||1983-1991, 1995-2013||Yes||All||Population size ≥ 250,000||Year, month and day of the week|
|Matched multiple birth||1995-2000||All states and counties or exact dates are available only through the NCHS Research Data Center|
* Exact dates are available only to federal employees and contractors; non-federal researchers, including federal grantees, may access this information through the NCHS Research Data Center.