National Vital Statistics System (NVSS)

Overview

NVSS collects and publishes official national statistics on births, deaths, and, before 1996, marriages and divorces occurring in the United States, based on U.S. standard certificates. The vital statistics files—Birth, Mortality Multiple Cause-of-Death, and Compressed Mortality—are detailed as follows.

Coverage

NVSS collects and presents U.S. resident data for the aggregate of 50 states, New York City, and the District of Columbia (D.C.), as well as for each state, D.C., and the U.S. territories of American Samoa, Guam, Northern Mariana Islands, Puerto Rico, and U.S. Virgin Islands. Vital events occurring in the United States to non-U.S. residents and vital events occurring abroad to U.S. residents are excluded.

Methodology

NCHS’ Division of Vital Statistics obtains information on births and deaths from the registration offices of each of the 50 states, New York City, D.C., American Samoa, Guam, Northern Mariana Islands, Puerto Rico, and U.S. Virgin Islands. Until 1972, NCHS processed microfilm copies of all death certificates and a 50% sample of birth certificates received from all registration areas. In 1972, some states began sending their data to NCHS through the Cooperative Health Statistics System (CHSS). States that participated in the CHSS program processed 100% of their death and birth records and sent the entire data file to NCHS on computer tapes. Currently, data are sent to NCHS following procedures similar to those under CHSS. The number of participating states grew from 6 in 1972 to 46 in 1984. Starting in 1985, all 50 states and D.C. participate in the Vital Statistics Cooperative Program.

U.S. Standard Certificates of Live Birth and Death Reports are revised periodically, allowing evaluation and the addition, modification, and deletion of items. Beginning with 1989, revised standard certificates replaced the 1978 versions. The 1989 revision of the death certificate included items on educational attainment and Hispanic origin of decedents, as well as changes to improve the medical certification of cause of death. Standard certificates recommended by NCHS are modified in each registration area to serve the area’s needs. However, most certificates conform closely in content and arrangement to the standard certificate, and all certificates contain a minimum data set specified by NCHS. The 2003 revision of vital records was implemented by some states and territories beginning in 2003 and by increasingly more areas so that full implementation in all states and D.C. was achieved in 2016 for birth data and 2018 for death data. The 2003 revision of the birth and death certificates included changes in the determination of multiple races and education level, among others.

Birth File

Overview

Vital statistics natality data are a fundamental source of demographic, geographic, and medical and health information on all births occurring in the United States. This is one of the few sources of comparable health-related data for small geographic areas over an extended time period. The data are used to present the characteristics of babies and their mothers, track trends such as birth rates for teenagers, and compare natality trends with those in other countries.

The birth file includes characteristics of the baby, such as sex, birthweight, and weeks of gestation; demographic information about the parents, such as age, race, Hispanic origin, parity, educational attainment, marital status, and state of residence; medical and health information, such as prenatal care based on hospital records; and behavioral risk factors for the birth, such as mother’s tobacco use during pregnancy.

Coverage

Birth data presented in Health, United States are based on reporting from all 50 states and D.C. Data for Alaska have been included starting in 1959, and data for Hawaii starting in 1960, after each gained statehood. Beginning with 1970, births to nonresidents of the United States are excluded.

Methodology

In the United States, state laws require birth certificates to be completed for all births. The registration of births is the responsibility of the professional attendant at birth, generally a physician or midwife. The birth certificate must be filed with the local registrar of the district in which the birth occurs. Each birth must be reported promptly; the reporting requirements vary from state to state, ranging from 24 hours to 10 days after the birth.

Federal law mandates national collection and publication of birth and other vital statistics data (Pub. L. 93-353). NVSS is the result of cooperation between NCHS and the states to provide access to statistical information from birth certificates. Standard forms for the collection of the data, and model procedures for uniform registration of the events, are developed and recommended for state use through cooperative activities of the states and NCHS. NCHS shares the costs incurred by the states in providing vital statistics data for national use.

Issues Affecting Interpretation

The 2003 revision of the U.S Standard Certificate of Live Birth uses revised race and ethnicity sections conforming to the 1997 “Revisions to the Standards for the Classification of Federal Data on Race and Ethnicity.” Starting with 2003 data, some states began using the 2003 revision of the U.S. Standard Certificate of Live Birth, which incorporated the 1997 federal Office of Management and Budget (OMB) standards allowing the reporting of more than one race (multiple races). Until all states adopted the 2003 revision and the 1997 OMB standards, data needed to be bridged to the 1977 standards. As of 2016, all states, territories (except American Samoa), and reporting areas had adopted the 2003 revision of the birth certificate, making it possible to report data using the 1997 categories. While the 1997 standard allows for the reporting of more than one race, estimates are presented for single-race groups (those only reporting one race). Consequently, data for race groups for 2016 and subsequent years are not completely comparable with earlier data. Interpretation of trend data should take into consideration changes to reporting areas and standards. For methodological and reporting area changes on specific birth certificate items, see Sources and Definitions, Age; Hispanic origin; Marital status; Race.

Reference

Martin JA, Hamilton BE, Osterman MJK, Driscoll AK. Births: Final data for 2019. National Vital Statistics Reports; vol 70 no 2. Hyattsville, MD: National Center for Health Statistics. 2021. Available from: https://www.cdc.gov/nchs/data/nvsr/nvsr70/nvsr70-02-508.pdf.

For more information, see the NVSS Birth Data website at: https://www.cdc.gov/nchs/nvss/births.htm, and the Vital Statistics Online Data Portal at: https://www.cdc.gov/nchs/data_access/Vitalstatsonline.htm.

Mortality Multiple Cause-of-Death File

Overview

Vital statistics mortality data are a fundamental source of demographic, geographic, and underlying and multiple cause-of-death information. Multiple cause-of-death data reflect all medical information reported on death certificates and complement traditional underlying cause-of-death data. Multiple-cause data give information on diseases that are a factor in death, whether or not they are the underlying cause of death; on associations among diseases; and on injuries leading to death.

The mortality multiple cause-of-death file includes demographic information on age, sex, race, Hispanic origin, state of residence, and educational attainment, as well as medical information on causes of death. This data set is one of the few sources of comparable health-related data for small geographic areas over an extended time period. The data are used to present the characteristics of those who die in the United States, determine life expectancy, and compare mortality trends with those in other countries.

Coverage

Mortality data presented in Health, United States are based on reporting from all 50 states and D.C. Data for Alaska have been included starting in 1959, and data for Hawaii starting in 1960, after each gained statehood. Beginning with 1970, mortality statistics for the United States exclude deaths of U.S. nonresidents.

Methodology

The registration of deaths is the responsibility of the funeral director. The funeral director obtains demographic data for the death certificate from an informant. The physician in attendance at the death is required to certify the cause of death. Where cause of death is from other than natural causes, a coroner or medical examiner may be required to examine the body and certify the cause of death. For more information on the funeral director’s role in death registration reporting, see Curtin et al. For more information on the role of the medical examiner and coroner systems for data quality, see Miniño et al.

NCHS is responsible for compiling and publishing annual national statistics on causes of death. In carrying out this responsibility, NCHS adheres to World Health Organization (WHO) Nomenclature Regulations. These regulations require a) that cause of death be coded according to the applicable revision of the International Classification of Diseases (ICD) (see Sources and Definitions, International Classification of Diseases [ICD]); and b) that underlying cause of death be selected according to international rules. Traditionally, national mortality statistics have been based on a count of deaths, with one underlying cause assigned for each death.

Before 1968, mortality medical data were based on manual coding of an underlying cause of death for each certificate according to WHO rules. Starting with 1968, NCHS converted to computerized coding of the underlying cause and manual coding of all causes (multiple causes) on the death certificate. In this system, called Automated Classification of Medical Entities (ACME), multiple-cause codes serve as inputs to the computer software, which uses WHO rules to select the underlying cause. ACME is used to select the underlying cause of death for all death certificates in the United States, and cause-of-death data in Health, United States are coded using ACME.

In addition, NCHS has developed two computer systems as inputs to ACME. Beginning with 1990 data, the Mortality Medical Indexing, Classification, and Retrieval system (MICAR) was introduced to automate coding of multiple causes of death. MICAR provides more detailed information on the conditions reported on death certificates than is available through the ICD code structure. Then, beginning with data year 1993, SuperMICAR, an enhancement of MICAR, was introduced. SuperMICAR allows for literal entry of the multiple cause-of-death text as reported by the certifier. This information is then processed automatically by the MICAR and ACME computer systems. Records that cannot be processed automatically by MICAR or SuperMICAR are multiple-cause-coded manually and then further processed through ACME. Starting in 2003, SuperMICAR was used to process all of the country’s death records.

Data for the entire United States refer to events occurring within the 50 states and D.C.; data for geographic areas are by place of residence. For methodological and reporting area changes for specific death certificate items, see Sources and Definitions, Hispanic origin; Race.

Issues Affecting Interpretation

ICD, by which cause of death is coded and classified, is revised about every 10 to 20 years. Because ICD revisions may cause discontinuities in trend data by cause of death, comparison of death rates by cause of death across ICD revisions should be done with caution and with reference to the comparability ratio (see Sources and Definitions, Comparability ratio). Before 1999, modifications to ICD were made only when a new ICD revision was implemented. A process for updating ICD was introduced with the 10th revision (ICD–10) that allows for midrevision changes. These changes, however, may affect comparability of data between years for select causes of death. Minor changes may be implemented every year, whereas major changes may be implemented every 3 years (for example, 2003 data year). In data year 2006, major changes were implemented, including the addition and deletion of several ICD codes. For more information, see Heron et al.

Multiple-cause data were obtained from all certificates for 1968–1971, 1973–1980, and 1983–present. Data were obtained from a 50% sample of certificates for 1972. Multiple-cause data for 1981 and 1982 were obtained from a 50% sample of certificates from 19 registration areas. For the other states, data were obtained from all certificates.

The death certificate has been revised periodically. A revised U.S. Standard Certificate of Death was recommended for state use as of January 1, 1989. Among the changes were the addition of new items on educational attainment and Hispanic origin of the decedent, and changes to improve the medical certification of cause of death. The U.S. Standard Certificate of Death was revised again in 2003; states adopted this new certificate on a rolling basis.

The 2003 revision of the U.S Standard Certificate of Live Birth uses revised race and ethnicity sections conforming to the 1997 “Revisions to the Standards for the Classification of Federal Data on Race and Ethnicity.” Starting with 2003 data, some states began using the 2003 revision of the U.S. Standard Certificate of Death, which incorporated the 1997 OMB standards allowing the reporting of more than one race (multiple races). Until all states adopted the 2003 revision and the 1997 OMB standards, data needed to be bridged to the 1977 standards. As of 2018, all states reported deaths using the 2003 revision of the death certificate, making it possible to report data using the 1997 categories. While the 1997 standard allows for the reporting of more than one race, estimates are presented for single-race groups (those reporting only one race). Consequently, data for race groups for 2018 and subsequent years are not completely comparable with earlier data. Interpretation of trend data should take into consideration changes to standards. For more information on the impact of the 2003 certificate revisions on mortality data presented in Health, United States, see Sources and Definitions, Race.

References

• Heron M, Hoyert DL, Murphy SL, Xu JQ, Kochanek KD, Tejada-Vera B. Deaths: Final data for 2006. National Vital Statistics Reports; vol 57 no 14. Hyattsville, MD: National Center for Health Statistics. 2009. Available from: https://www.cdc.gov/nchs/data/nvsr/nvsr57/nvsr57_14.pdf.
• Miniño AM, Anderson RN, Fingerhut LA, Boudreault MA, Warner M. Deaths: Injuries, 2002. National Vital Statistics Reports; vol 54 no 10. Hyattsville, MD: National Center for Health Statistics. 2006. Available from: https://www.cdc.gov/nchs/data/nvsr/nvsr54/nvsr54_10.pdf.
• National Center for Health Statistics. Multiple causes of death in the United States. Monthly Vital Statistics Report; vol 32 no 10 suppl 2. Hyattsville, MD: National Center for Health Statistics. 1984. Available from: https://www.cdc.gov/nchs/data/mvsr/supp/mv32_10s2.pdf.

For more information, see the NCHS Mortality Statistics website at: https://www.cdc.gov/nchs/deaths.htm.