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National Vital Statistics System (NVSS)

National Center for Health Statistics (NCHS)

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Updated June 9, 2025

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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, Fetal Death, Period Linked Birth/Infant Death, and Mortality Multiple Cause-of-Death—are detailed as follows.

Coverage

NVSS collects and presents U.S. resident data for all 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’s 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. The revision was fully implemented in all states and D.C. and 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

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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 birthweight, sex, and weeks of gestation; demographic information about the parents, such as age, educational attainment, marital status, parity, race and Hispanic origin, 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 in 2003, some states began using the 2003 revision of the U.S. Standard Certificate of Live Birth, which incorporated the 1997 Office of Management and Budget (OMB) “Revisions to the Standards for the Classification of Federal Data on Race and Ethnicity,” which allow for the reporting of more than one race (multiple races). Until all states adopted the 2003 revision and the 1997 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 standards allow for the reporting of more than one race, estimates are presented for single-race groups (those only reporting one race). As a result, race data for 2016 and beyond 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

  • Osterman MJK, Hamilton BE, Martin JA, Driscoll AK, Valenzuela CP. Births: Final data for 2022. National Vital Statistics Reports; vol 73 no 2. Hyattsville, MD: National Center for Health Statistics. 2024. Available from: .

For more information, see the NVSS Birth Data website and the Vital Statistics Online Data Portal.

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Fetal Death Data Set

Overview

In Health, United States, data are presented for fetal deaths at 20 weeks or more. The Fetal Death Data Set includes characteristics of the fetus, such as sex, birthweight, and weeks of gestation; demographic information about the mother, such as age, race, Hispanic origin, and live-birth order; and medical and health information of the mother, such as maternal diabetes and hypertension.

Coverage

Data presented in Health, United States are based on reporting from all 50 states and D.C. Data for Puerto Rico, U.S. Virgin Islands, Guam, American Samoa, and Northern Marianas are not included in U.S. totals but may be included in the fetal death user’s guides and in periodic reports, available from the Vital Statistics Online Data Portal.

Methodology

State laws require the reporting of fetal deaths, and federal law mandates national collection and publication of fetal death data (P. L. 93-353). States and reporting areas submit fetal mortality data to NCHS as part of a cooperative agreement. Standard forms and procedures for the collection of the data 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.

In addition to fetal mortality rates, perinatal mortality rates are also presented in Health, United States. Perinatal mortality includes both late fetal deaths (at least 28 weeks of gestation) and early infant (neonatal) deaths (within 7 days of birth). Data on early infant deaths come from the Linked Birth/Infant Death Data Set.

Issues Affecting Interpretation

Reporting requirements for fetal deaths vary by state, and these differences have important implications for comparisons of fetal mortality rates by state. The majority of states require reporting of fetal deaths at 20 weeks of gestation or more, or a minimum of 350 grams birthweight (roughly equal to 20 weeks), or some combination of the two. In 2021, 6 states required reporting of fetal deaths at all periods of gestation, 2 states at 12 weeks of gestation, and 1 state beginning at 16 weeks of gestation.

Starting with 2014 data, the obstetric estimate of gestation at delivery (OE) is used to determine gestational age, instead of the date of last normal menses (LMP), which was used for earlier years. The adoption of OE for gestational age had no or very little impact on total fetal mortality rates. However, late fetal mortality rates based on the OE were lower than those based on the LMP. For more information, see “.”

There is substantial evidence that not all fetal deaths for which reporting is required are, in fact, reported. Underreporting of fetal deaths is most likely to occur in the earlier part of the required reporting period for each state. For example, in 2021, for those states requiring reporting of fetal deaths at all periods of gestation, 54.4% of fetal deaths at 20 weeks or more of gestation were at 20–27 weeks, whereas for states requiring reporting of fetal deaths at 20 weeks or more of gestation or 350 grams or more, 50.9% were at 20–27 weeks, indicating possible underreporting of early fetal deaths in some states.

References

  • Gregory ECW, Valenzuela CP, Hoyert DL. Fetal mortality: United States, 2021. National Vital Statistics Reports; vol 72 no 8. Hyattsville, MD: National Center for Health Statistics. 2023. DOI: .
  • Valenzuela CP, Gregory ECW, Martin JA. Perinatal mortality in the United States, 2020–2021. NCHS Data Brief, no 489. Hyattsville, MD: National Center for Health Statistics. 2023. DOI: .
  • National Center for Health Statistics. . Hyattsville, MD: National Center for Health Statistics. 2018.

For more information, see the .

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Linked Birth/Infant Death Data Set

Overview

National linked files of live births and infant deaths are the primary data set for analyzing U.S. infant mortality trends and characteristics related to birth. It is also the preferred source for examining infant mortality by race and Hispanic origin. The Linked Birth/Infant Death Data Set includes all infant deaths reported on death certificates that can be linked to their corresponding birth certificates. The purpose of the linkage is to use the many additional variables from the birth certificate, including the more accurate race and ethnicity data, for more detailed analyses of infant mortality patterns. The Linked Birth/Infant Death Data Set includes all variables on the birth file, including race and Hispanic origin, birthweight, and maternal smoking, as well as variables on the mortality file, including cause of death and age at death.

Coverage

To be included in the U.S. linked file, both the birth and death must have occurred in the 50 states, D.C., Puerto Rico, or Guam. Linked birth/infant death data are not available for American Samoa, Northern Marianas, or U.S. Virgin Islands. Data presented in Health, United States are based on reporting from all 50 states and D.C.

Methodology

Infant deaths are defined as a death before the infant’s first birthday. In 2021, 98.9% of infant death records were linked to their corresponding birth certificates. The linkage makes available extensive information from the birth certificate about the pregnancy, maternal risk factors, infant characteristics, and health items at birth that can be used for more detailed analyses of infant mortality. The linked file is the preferred source for calculating infant mortality rates by race and Hispanic origin, because this information is more accurately measured from the birth certificate, where race and Hispanic origin are self-reported by the mother or family members. Infant mortality rates by race and Hispanic origin calculated using the mortality file are based on information from the death certificate, which is reported by the funeral director as provided by an informant (often the surviving next of kin), or in the absence of an informant, on the basis of observation. For information about the reporting of race and Hispanic origin, see Sources and Definitions, Hispanic origin; Race.

Starting with 1995 data, linked birth/infant death data files are available for period and birth cohort data. The numerator for the period linked file consists of all infant deaths occurring in a given data year linked to their corresponding birth certificates, whether the birth occurred in that year or the previous year. The numerator for the birth cohort linked file consists of deaths to infants born in a given year. In both formats, the denominator is all births occurring in the year. For example, the 2019 period linked file contains a numerator file that consists of all infant deaths occurring in 2019 that have been linked to their corresponding birth certificates, whether the birth occurred in 2018 or 2019. In contrast, the 2019 birth cohort linked file will contain a numerator file that consists of all infant deaths to babies born in 2019, whether the death occurred in 2019 or 2020. Although the birth cohort format has methodological advantages, it creates substantial delays in data availability, because it is necessary to wait until the close of the following data year to include all infant deaths in the birth cohort. Starting with 1995 data, period linked files are used for infant mortality rate data sets in Health, United States. Other changes to the data set starting with 1995 include the addition of record weights to compensate for the 1%–2% of infant death records that could not be linked to their corresponding birth records.

Issues Affecting Interpretation

Period linked file data starting with 1995 are not strictly comparable with birth cohort data for 1983–1991. Denominators for infant mortality rates are based on the number of live births, rather than on population estimates. For information about the reporting of race and Hispanic origin or reporting area changes for the birth certificate items, see Sources and Definitions, Age; Hispanic origin; Race.

References

For more information, see the NCHS Linked Birth/Infant Death Data website.

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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-of-death data give information on diseases that were a factor in death, whether or not they were 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, educational attainment, race and Hispanic origin, sex, and state of residence, 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 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 in 1970, mortality statistics for the United States exclude the 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. In cases without a natural cause of death, 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 the Funeral Director’s Handbook: Death Registration and Fetal Death Reporting. For more information on the role of the medical examiner and coroner systems for data quality, see Deaths: Injuries, 2002.

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 that a) 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) 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 in 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 software systems as inputs to ACME. Beginning with 1990 data, the Mortality Medical Indexing, Classification, and Retrieval system (MICAR) was introduced to automate the 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. In 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 software systems. Records that cannot be processed automatically by MICAR or SuperMICAR are manually coded using multiple cause-of-death codes 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, which is used to code and classify cause of death, 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. In data year 2006, major changes were implemented, including the addition and deletion of several ICD codes. For more information, see Deaths: Final data for 2006.

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 Death 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 standards allowing the reporting of more than one race (multiple races). Until all states adopted the 2003 revision and the 1997 standards, data needed to be bridged to the 1977 standards. Starting in 2018, all states report deaths using the 2003 revision of the death certificate, making it possible to report data using the 1997 standards. While the 1997 standards allow for the reporting of more than one race, estimates are presented for single-race groups (those reporting only one race). As a result, race data for 2018 and beyond 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

  • Xu JQ, Murphy SL, Kochanek KD, Arias E. Deaths: Final data for 2021. National Vital Statistics Report; vol 73 no 8. Hyattsville, MD: National Center for Health Statistics. 2024.
  • 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.
  • 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.
  • 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.

For more information, see the NCHS Mortality Statistics.

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