National Vital Statistics System

Restricted-Use Vital Statistics Data

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Since 2005, national vital statistics microdata files containing state, county, or large-city geographic details have not been available without prior approval. This restriction is necessary to protect confidentiality, as the level of detail in these files makes them inappropriate for public release.

Access to, and use of, restricted versions of national vital statistics 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 provided below. Please review the Data Release Policy for Vital Statistics Micro-data Files before preparing an application.

Descriptions of data files/record layouts

The following data file descriptions and record layouts are available for different types of restricted data:

NCHS made changes to how maternal mortality data are coded, published, and released beginning with 2018 data (see National Vital Statistics Reports Volume 69, Number 2 January, 2020). The official data files for 2003–2017, which had already been released, were not revised. These public-use files, along with corresponding documentation and user guides, remain available for download. In addition, NCHS has produced special research files reflecting alternative methods, as described below.

For the data files previously released for 2003–2017, additional recoded restricted-use files are available to researchers. These files provide access to cause-of-death codes generated using alternate coding methods and allow maximum flexibility for analyses based on different methods and assumptions.

As discussed in the publication noted above, the pre-2003 method underestimated maternal deaths, the 2003–2017 method overestimated maternal deaths (particularly among older women), and the 2018 method was designed to reduce the effect of likely errors in the checkbox. Trend analyses of pre-2018 data using either the 2003–2017 or 2018 method are limited by the incremental implementation of the pregnancy checkbox.

Unlike the publicly available files, the restricted-use research files contain geographic variables related to the decedent. See Documentation on variables and notes on how to analyze the data  [PDF – 296 KB] for detailed information.

How to apply

Those interested in accessing restricted datasets must complete the Project Review Form  [PDF – 499 KB]. Email the completed form (do not alter the form name), along with all supporting material (see below), to nvssrestricteddata@cdc.gov.

  • Include CVs of all individuals who will have access to the dataset(s).
    • PDF files only; please name each file as: “CV – Last_Name”
    • Do not send a ZIP file or combine multiple CVs into a single document.
  • 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 include the following:

  • Advisor’s CV
    • PDF file only; please name the file as: “CV – Last_Name”
  • Letter of support from advisor
    • Must be a signed letter on the advisor’s letterhead
    • PDF file only; please name the file as: “LOS – Last_Name_of_PI”

Failure to include all required information, as outlined above and in the application, will delay processing.

If you are working under a deadline, please note the date in your original email submission. While we cannot guarantee processing by a specific date, we will take your deadline into consideration.

Please note: NCHS will no longer accept applications based on the previous 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: Such requests should be directed to the corresponding state vital records office)
  • Requests for geographic data below the levels described in the file descriptions
  • Requests requiring exact dates (month and year are available, but exact day is not; see the data release policy for details)
  • Requests for data files to be sent to, or accessed remotely from, outside the United States or its territories
  • Requests to link the data to other datasets in ways that may re-identify cases
  • Requests that involve using NCHS data for commercial or resale purposes

Submitted applications

NCHS will evaluate each request; please allow up to 4 weeks for processing. During the process, NCHS reviewers may request additional information from the applicant by email. Applicants should monitor their email and respond promptly to avoid delays.

If approved, the applicant will gain access to the files upon submission of a signed NCHS Data Use Agreement (DUA). The DUA must be executed by an official authorized to sign agreements on behalf of the applicant’s institution or organization (i.e., a dean of a college, vice president of a company, or government division director). The signatory must not be the project’s Principal Investigator(s), co-investigators, or analysts. If files will be housed at more than one institution, a separate agreement is required for each institution.

The NCHS DUA requires valid digital signatures generated using a digital certificate and bound through Public Key Infrastructure.

NCHS does not provide blanket approvals; all approvals are project-specific, time-specific, and individual/institution-specific.

If an application is denied, applicants will be informed of the reason(s) for denial.

If you have not received a decision within 4 weeks, you may check the status of your application by forwarding your original application and requesting an update at nvssrestricteddata@cdc.gov.

Conditions of use for restricted data

Once researchers are approved to access restricted-use data, all data users associated with the approved research project must agree to the following conditions:

  1. Researchers and associates will use a data file only for the purpose stated in the proposed scope of work.
  2. The researcher will 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, or permit others to attempt to link the dataset with individually identifiable records from any other NCHS or non-NCHS dataset.
  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.
  8. Student researchers must store data files on the secure computer system of their university.
  9. Storage and access of data files using portable storage devices or commercial cloud services (e.g., Dropbox, Google Drive, Microsoft Azure, Amazon Web Services, etc.) are prohibited.

Compliance with all NCHS data protection requirements is mandatory