National Vital Statistics System

Restricted-Use Vital Statistics Data

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Since 2005, national vital statistics micro-data files that include state, county, or larger city geography are no longer available without approval. This restriction was necessary to preserve confidentiality. The data in the restricted files are at such a level of detail that open access to the public is not appropriate.

Access to, and use of, restricted versions of national vital statistical files require research-proposal review and approval by the National Center for Health Statistics (NCHS). Information on available restricted data files and how to apply is below. Please review our Data Release Policy for Vital Statistics Micro-data Files before preparing an application.

Descriptions of Data Files/Record Layouts

Following are Data File Descriptions/Record Layouts for different types of restricted data:

NCHS made changes in how code, publish, and release maternal mortality data beginning with 2018 data (National Vital Statistics Reports Volume 69, Number 2 January, 2020). The official data files for 2003–2017 already released were not changed. These publicly-available files are available for download, along with data documentation/users’ guides. However, NCHS produced special research files reflecting different methods as discussed below.

For the data files that have been released previously (2003–2017), an additional, separate restricted-use data file will be available to researchers through the NCHS Research Data Center. These data will provide researchers with access to cause-of-death codes using alternate coding methods and provide maximum flexibility for analysis using different methods and assumptions. As addressed in the publication noted above, the pre-2003 method underestimated maternal deaths, the 2003–2017 method overestimated maternal deaths especially for older women, and the 2018 method is designed to lessen the effect of likely errors in the checkbox. Trend analyses for data pre-2018 using either the 2003–2017 or 2018 method are limited by the incremental implementation of the checkbox. Unlike the publicly-available files, the restricted research files contain geographical variables about the decedent. Documentation on variables and notes on how to analyze the data [PDF – 296 KB].

How to Apply

Those interested in accessing restricted datasets must complete the Project Review Form [PDF – 499 KB]. Email the completed form, along with ALL supporting material (see below), to nvssrestricteddata@cdc.gov.

  • Include CVs of all individuals who will have access to the dataset(s)
  • Provide any additional details about the project needed to help us understand how you will use the data. This helps avoid additional queries from NCHS that can create delays in processing.
  • Submit only one application per project, regardless of the number of co-investigators.

Student applicants must also always include the following:

  • Advisor’s CV
  • Letter of support from advisor
    • This may be in the form of a signed letter on the advisor’s letterhead (which can be attached to the application as a PDF) or an email sent directly from the advisor to NCHS

Failure to include all required information listed above and in the application will delay processing.

If you are working on a deadline, please include the date in your original email submission. While we are unable to guarantee processing by any specific date, we will make note of the deadline provided.

Please note: NCHS will no longer accept applications based on the previous (NAPHSIS) Project Review Form.

Preparing a Successful Application

Appropriate requests will demonstrate:

  • An intended use that focuses on studies of health and the factors affecting heath
  • A reasonable likelihood of contributing to knowledge on a health-related issue

Types of requests that are NOT appropriate include:

  • Requests that do not involve an evaluation of health or factors related to health
  • Requests that plan to assess a single state (Note: single state data request should be directed to the corresponding state vital records office).
  • Requests for geographic data below the levels described in the file descriptions
  • Requests that require exact dates (month and year are available, exact day is not. See the data release policy for details)
  • Requests for data files that would be sent, or accessed remotely from, outside the United States or its territories
  • Requests that would link the data to other data sets which may re-identify cases
  • Requests that involve using the data for commercial or resale purposes

Submitted Applications

NCHS will evaluate the data request. Please allow 4-6 weeks for processing. During the process, NCHS reviewers may request further information from the applicant by email – please check your emails and respond to any NCHS queries as quickly as possible to avoid further delays.

If approved, the applicant will have access to the files upon submission of a signed NCHS Data Use Agreement.  An official who is authorized to execute agreements on behalf of the applicant’s institution or organization must signify compliance with the terms of the Agreement; this should be someone other than the project’s Principal Investigator(s), co-investigators, or analysts. If copies of the files will be housed at more than one institution, an Agreement is required for each institution.

If denied, the applicant will be provided the reason(s) for denial.

If you have not been notified about a decision after 4-6 weeks, you may check on the status of your application. Please forward your original application and request a status update by emailing NCHS at nvssrestricteddata@cdc.gov.

Conditions of Use for Restricted Data

Once researchers have applied for and received approval to access restricted-use data, all data users associated with an approved research project must agree to specific conditions of usage, including the following:

  1. Researchers and associates will use a data file only for the purpose stated in the proposed scope of work.
  2. The researcher will return the micro-data or compressed files to NCHS or destroy the data files after the approved project period unless renewal is requested and approved.
  3. The data files cannot be shared with any other individual not listed in the data use agreement.
  4. The data files cannot be accessed directly or remotely outside the United States by any individual listed in the data use agreement.
  5. Researchers and associates will not attempt to link nor permit others to attempt to link the data set with individually identifiable records from any other NCHS or non-NCHS data set.
  6. Researchers and associates will not attempt to use the data sets nor permit others to use them to learn the identity of any person or establishment included in any data set.
  7. The data files should be stored on, and accessed from, the secure computer system of the researcher’s affiliated organization or institution. This means that files will be housed on a server that is behind a firewall, has data encryption, permits file access only to the approved researchers, and has encrypted network communications; the researcher would then access the files from a password-protected institutional desktop or laptop. If a secure computer system is not available, files should be stored on an encrypted, password-protected, stand-alone computer or laptop protected by anti-virus and anti-malware software. The computer or laptop should be air-gapped for additional security as feasible. Permission from NCHS is required to store data files on a personal computer or laptop.
  8. Student researchers are required to store data files on the secure computer system of their university.
  9. Storage and access of data files using a cloud-based system is not permitted.