KIDS COUNT Data Center

Introduction
Here we provide definitions for all measures and technical terms used in The Right Start for America’s Newborns and in related material on this website. We also address situations where there have been changes or problems in the way state-level data have been collected, coded or reported by state departments of health. Such changes can result in substantial year-to-year changes in statistics that are due, at least in part, to the change in the methodology used to collect and report the data rather than to actual changes in behavior. All data are reported by the mother’s place of residence, not the place where the infant was born.

Prior to 2003, all states used the 1989 Revision of the U.S. Standard Certificate of Live Birth.¹ However, beginning in 2003, states began to adopt the 2003 Revision of the U.S. Standard Certificate of Live Birth. In 2003, Pennsylvania and Washington adopted the 2003 Certificate, and in January 2004, Idaho, Kentucky, New York (excluding New York City), South Carolina, and Tennessee adopted the revised certificate. Two additional states, Florida and New Hampshire, implemented the revised birth certificate in 2004, but after January 1.

Data for educational attainment, prenatal care, and tobacco use, although collected on both the revised and unrevised certificates, are not considered comparable between revisions, The discussion of individual measures in the next section provides details on the lack of comparability.

More specifically, for the states that have adopted the revised certificate, it is not appropriate to construct trends for maternal education, prenatal care, and tobacco use if the trend period includes the year in which the state adopted the revised certificate. Similarly, it is not appropriate to compare data on maternal education, prenatal care, and tobacco use for states using the 1989 certificate with data on these three measures for states using the 2003 certificate.

All percentages in the state tables are rounded to the nearest tenth of a percent. Thus, 9.46 percent is rounded to 9.5 percent in the tables.

Definitions and data sources

Births to unmarried women (percent of total births to unmarried women) is the percentage of all births occurring to women who were unmarried at the time of the birth. Marital status was obtained from a direct question on the birth certificate in 48 states and the District of Columbia. In Michigan and New York, marital status was inferred from other information on the birth certificate. In 2003, marital status was also imputed for some birth records in the 48 states and the District of Columbia where it was not reported from the direct question. See the next section for more details.

Sources: 1990-2004 Natality Data Set CD Series 21, numbers 2-9, 11-12, 14-16 (SETS versions), and 16H and 17Ha (ASCII version), National Center for Health Statistics.

Data for Nevada for 1995 and 1996 only are from the Technical Notes in Ventura, S.J., Martin, J.A., Curtin S.C., Mathews T.J. (1998), “Births: Final data for 1997,” National Vital Statistics Reports; Vol 47 no 18. Hyattsville, Maryland: National Center for Health Statistics.

Late or no prenatal care (percent of total births to mothers receiving late or no prenatal care) is the percentage of births that occurred to mothers who reported receiving prenatal care only in the third trimester of their pregnancy, or reported receiving no prenatal care. Birth certificates that did not report information about prenatal care were not included in this calculation.

Beginning in 2003, the adoption of the revised birth certificate in several states produced “substantive changes in both question wording and the sources for [prenatal care] information [that] have resulted in data that are not comparable” with data for previous years.² Prior to the revision there were other reporting issues for a few states in some years. See the next section for more details.

Sources: 1990-2004 Natality Data Set CD Series 21, numbers 2-9, 11-12, 14-16 (SETS versions), and 16H and 17Ha (ASCII version), National Center for Health Statistics.

Low-birthweight births (percent low-birthweight births) is the percentage of live births weighing less than 2,500 grams (5.5 pounds). Births of unknown weight were not included in these calculations.

Sources: 1990-2004 Natality Data Set CD Series 21, numbers 2-9, 11-12, 14-16 (SETS versions), and 16H and 17Ha (ASCII version), National Center for Health Statistics.

Low maternal education (percent of total births to mothers with less than 12 years of education) is the percentage of women who had completed fewer than 12 years of education at the time of the birth. Birth certificates on which maternal education was not reported were not included in this calculation. Data on maternal education were not available for two states in the early 1990s.

Beginning in 2003, the adoption of the revised birth certificate in several states produced substantive changes in the wording of the questions on maternal education that have resulted in data that are not comparable with data for previous years. See the next section for more details.

Sources: 1990-2004 Natality Data Set CD Series 21, numbers 2-9, 11-12, 14-16 (SETS versions), and 16H and 17Ha (ASCII version), National Center for Health Statistics.

Number of births by race and ethnicity of mother contains information about race/Hispanic origin of the mother. On birth certificates, as on most federal data collection forms, the question regarding whether a person is Hispanic is separate from the question asking whether a person is white, black, Asian or Pacific Islander, or American Indian. Thus, people are asked to select a racial group and to indicate whether they are of Hispanic origin. A birth to a woman who reported that she was Hispanic and white would usually be included in figures for both of these groups. In order to create mutually exclusive categories, Hispanics were removed from the black and white racial categories in the tabulations presented here. This allows more meaningful comparisons between minorities and the group people typically think of when we say “white.”

It should also be noted that these figures represent the race of the mother, not the race of the child. This is important because increasing numbers of children are born to parents of different races.

Births for which Hispanic origin was not reported are included in the “Other” category.

In 1990, Oklahoma did not collect data on Hispanic origin. New Hampshire did not report Hispanic origin until 1993 and did not collect this information reliably until 1994.

Starting in 2003, multiple race reporting was allowed by several states. See the next section for more details.

Sources: 1990-2004 Natality Data Set CD Series 21, numbers 2-9, 11-12, 14-16 (SETS versions), and 16H and 17Ha (ASCII version), National Center for Health Statistics.

Preterm births (percent preterm births) is the percentage of babies born with a gestational age of less than 37 completed weeks. Birth certificates that did not report gestational age were not included in this tabulation.

Sources: 1990-2004 Natality Data Set CD Series 21, numbers 2-9, 11-12, 14-16 (SETS versions), and 16H and 17Ha (ASCII version), National Center for Health Statistics.

Repeat teen births (percent of teen births to women who were already mothers) is the percentage of births that were second or higher order births to mothers who were under the age of 20 at the time of the birth. Birth certificates that did not contain information on birth order were not included in this calculation.

Sources: 1990-2003 Natality Data Set CD Series 21, numbers 2-9, 11-12, 14-16 (SETS versions), and 16H (ASCII version), National Center for Health Statistics.

Smoking during pregnancy (percent of total births to mothers who smoked during pregnancy) is the percentage of women who smoked during pregnancy. Data for smoking were not collected in NCHS’ standard format in California and are therefore not reported.

Birth certificates on which information on smoking during pregnancy was not reported were not included in this calculation.

Beginning in 2003, the adoption of the revised birth certificate in several states produced substantive changes in the wording of the questions on tobacco use that have resulted in data that are not comparable with data for previous years. See the next section for more details.

Sources: 1990-2004 Natality Data Set CD Series 21, numbers 2-9, 11-12, 14-16 (SETS versions), and 16H and 17Ha (ASCII version), National Center for Health Statistics.

Teen births (percent of total births to teens) was calculated by dividing the number of births to women under age 20 by the total number of births to women of all ages. It should be noted that this is not the same as a teen birth rate, which measures the risk that a teenager will give birth. The percentage of total births to women under age 20 is affected by the fertility of women over age 20, as well as the fertility of teenagers.

Sources: 1990-2004 Natality Data Set CD Series 21, numbers 2-9, 11-12, 14-16 (SETS versions), and 16H and 17Ha (ASCII version), National Center for Health Statistics.

U.S. Average is obtained by dividing total U.S. births with a given characteristic by total U.S. births (as reported by NCHS). For measures with incomplete reporting, the average is based only on those states with reported data. For measures which have changed for some states due to their adoption of the revised birth certificate, the Multi-state average only includes those states that are still using the 1989 version of the birth certificate.

In 2003-2004, two different multi-state averages have been used for comparison purposes. For states still using the 1989 certificate, a multi-state average restricted to those states using the 1989 certificate is shown. For the two states using the 2003 certificate in 2003, no multi-state average is displayed. In the states using the 2003 certificate in 2004, a multi-state average restricted to those states that adopted the 2003 certificate no later than January 1, 2004, is shown.

Reporting issues

Births to unmarried women.³ Since 1998, births to unmarried women have been “identified by a question on the birth certificates of all but two States. . . . In the two States (Michigan and New York) that use inferential procedures to compile birth statistics by marital status . . . , a birth is inferred as nonmarital if either of these factors is present: a paternity acknowledgment⁴ was received or the father’s name is missing.”

However, in 1990, the first year included in this volume, six states used inferential procedures.⁵ Thus, during the 1990-2004 period covered by this volume, four states—California (1997), Connecticut (1998), Nevada (1997), and Texas (1994)—switched from using inferential procedures to using a direct question to identify births to unmarried women.⁶ At each of these transition points, there is the potential for the percentage of births to unmarried women to change because of the change in the method of identifying births to unmarried women.

In addition, among those states using inferential procedures, in some states the inferential procedures changed during the 1990-2002 period. For example, in the counts of births to unmarried women submitted by Michigan to NCHS, births with paternity acknowledgments were counted as births to unmarried women beginning in 1994. Thus, there is an undercount of about 25 percent for births to unmarried women in Michigan between 1990 and 1993. Data for Texas are also incomplete during 1990-1993.

In 2003, mother’s marital status was not reported on 0.04 percent of birth records in the 48 states and the District of Columbia, where information was obtained via a direct question. For the missing records, marital status was imputed as married if the father’s age was known and unmarried if the father’s age was not known. This change in imputation had essentially no impact on percentages and rates of nonmarital births.7 Except in 2003, all cases of unreported marital status were imputed as married.

Table A2.1 summarizes the reporting transitions made by each of the affected states by providing the date of each change and the likely effect of the change in reporting as estimated by NCHS. In some cases, these changes have substantial effects on the percentage of births to unmarried women that are included in the tables in this volume. In such cases, trend analysis is either impossible or must be limited to an abbreviated period. All such cases are indicated with footnotes in the table.

Late or no prenatal care. Beginning in 2003, for states adopting the 2003 birth certificate, “substantive changes in both question wording and the sources for this information have resulted in data that are not comparable . . .” with data from prior years. “The wording of the prenatal care item was modified to ‘Date of first prenatal visit’ from ‘Month prenatal care began.’ In addition, the 2003 revision process resulted in recommendations that the prenatal care information be gathered from the prenatal care or medical records, whereas the 1989 revision did not recommend a source for these data.”⁸ Although we have reported data both pre- and post-revision years for those states adopting the revised certificate, these data are not comparable. Data for all other reporting states were based on the 1989 revision of the U.S. Standard Certificate of Live Birth.

In earlier years, there were several states in which the percentage of women who received late or no prenatal care changed substantially between two consecutive years. In these situations, we consulted with both NCHS staff and staff of the appropriate state department of health to check into the possibility that reporting problems were responsible, at least in part, for the changes.

2004 prenatal care data for New York State does not include New York City estimates because New York City continued to use the 1989 certificate, while the balance of New York State used the 2003 certificate. Data for 2004 for prenatal care cannot be presented for Florida and New Hampshire because they adopted the 2003 certificate after January 1, 2004.

Table A2.2 summarizes all instances in which reporting issues were documented.

Low maternal education. In 1990 and 1991, Washington and New York State (exclusive of New York City) did not require reporting of educational attainment. Beginning in 2003, for states adopting the 2003 birth certificate, substantive changes in question wording have resulted in data from prior years. The 2003 revisions to the U.S. Standard Certificate of Live Birth ask for the highest degree or level of school completed while the 1989 standard certificate asks the highest grade completed. These questions are too dissimilar to yield comparable results across years. Although we have reported data both pre- and post-revision years for those states adopting the revised certificate, these data are not comparable. Data for all other reporting states were based on the 1989 revision of the U.S. Standard Certificate of Live Birth.

2004 low maternal education data for New York State does not include New York City estimates because New York City continued to use the 1989 certificate, while the balance of New York State used the 2003 certificate.. Data for 2004 for maternal education cannot be presented for Florida and New Hampshire because they adopted the 2003 certificate after January 1, 2004.

Table A2.3 summarizes all instances in which reporting issues were documented.

Race and ethnicity. Oklahoma did not ask about Hispanic origin until 1991. New Hampshire began asking for Hispanic origin in 1993, but did not collect this information reliably until 1994. Thus, data on race and ethnicity of births are not included in the table in 1990 for Oklahoma and 1990-1993 for New Hampshire.

In Rhode Island, Hispanic origin was not reported or unknown for 13 to 14 percent of total births in 1998 and 1999—up from only 5 percent in 1990. While the percentage dropped to 8 percent in 2000, it increased again in 2001 to 11 percent. Consequently, the distribution of births by Hispanic origin is less reliable during the late 1990s and early 2000s than in the early 1990s. Over 90 percent of births with unknown Hispanic origin in 1998 were to white women.

In 2003, multiple race was reported by Pennsylvania and Washington, which used the 2003 revision of the U.S. Standard Certificate of Live Birth, as well as California, Hawaii, Ohio (for births occurring in December 2003 only), and Utah. Data from the remaining 44 States and the District of Columbia reported only the four races stipulated in the 1977 OMB standards: White, Black, American Indian or Alaskan Native, and Asian or Pacific Islander. In 2004, multiple race was reported by Florida (for births occurring from March 1, 2004, only), Idaho, Kentucky, New Hampshire (for births occurring from July 19, 2004, only), New York State (excluding New York City), Pennsylvania, South Carolina, Tennessee, and Washington, which used the 2003 revision of the U.S. Standard Certificate of Live Birth, as well as California, Hawaii, Michigan (for births at selected facilities only), Minnesota, Ohio, and Utah, which used the 1989 revision of the U.S. Standard Certificate of Live Birth. To maintain uniform and comparable data between states that report multiple race and those that do not, multiple race is mapped to one of the four races stipulated in the 1977 OMB standards. This report provides the number of births for four groups defined by race and Hispanic origin: non-Hispanic Whites, non-Hispanic Blacks, Hispanics, and Other, which includes American Indians, Asian-Pacific Islanders, and all those births where Hispanic origin is unknown or not stated.

Repeat teen births. In 1997 and 1998, the number of teen births in which birth order was unknown or not reported was extremely high in Oklahoma. Consequently, the statistics on the percentage of teen births to women who were already mothers are not reliable in those years and are not reported in this volume. Generally, most births with birth order unknown are first births. If it is assumed that most of the births with birth order unknown are actually first-order births, the resulting percentage of repeat teen births for Oklahoma is comparable to that in most other states. In 1999, Oklahoma’s reporting of live birth order improved considerably. Consequently, statistics on repeat teen births for repeat teen births are reported in this volume starting with 1999.

Smoking during pregnancy. South Dakota and California asked about smoking during pregnancy in a format that was not compatible with the standard recommended by NCHS throughout the 1990-1999 period. South Dakota began reporting this information in a compatible format in 2000. Oklahoma began reporting smoking data on the birth certificate in 1991, and New York City, a registration area separate from that of New York State, began reporting in 1994. Indiana and New York State began reporting smoking data in 1999.⁹ Between 2000 and 2002, data on smoking during pregnancy was reported in a standard format on all birth certificates in all states except for California.

Beginning in 2003, for states adopting the 2003 birth certificate, substantive changes in question wording have resulted in data from prior years. The tobacco-use-during-pregnancy question that was used in the 1989 revision had a yes or no question, while the 2003 revision asks for the number of cigarettes smoked at different intervals before and during pregnancy. These questions are too dissimilar to yield comparable results across years. Although we have reported data both pre- and post-revision years for those states adopting the revised certificate, these data are not comparable. Data for all other reporting states were based on the 1989 revision of the U.S. Standard Certificate of Live Birth.

Table A2.4 summarizes all instances in which reporting issues were documented.

TABLE A2.1. Summary of reporting issues for births to unmarried women

Sources: Ventura, S.J., Martin, J.A., Curtin S.C., Mathews T.J., and Park M.M. (2000), “Births: Final data for 1998,” National Vital Statistics Reports; Vol. 48, no. 3. Hyattsville, Maryland: National Center for Health Statistics. Ventura, S.J., Bachrach, C.A. (2000), “Nonmarital childbearing in the United States, 1940-1999,” I, Vol. 48, No. 16. Hyattsville, MD: National Center for Health Statistics. Ventura, S.J., Martin, J.A., Curtin S.C., Menacker, F., and Hamilton, B.E. (2001), “Births: Final data for 1999,” National Vital Statistics Reports; Vol. 49, no. 1. Hyattsville, Maryland: National Center for Health Statistics.

TABLE A2.2 Summary of reporting issues for the percentage of women receiving late or no prenatal care

TABLE A2.3 Summary of reporting issues for the percentage of women with low maternal education

TABLE A2.4 Summary of reporting issues for the percentage of women who smoked during pregnancy

1 All information on the revision to the U.S. Certificate of Live Birth are based on the discussion in the Technical Notes of Martin JA, Hamilton BE, Sutton PD, et al. Births: Final data for 2004. National vital statistics reports; vol 55 no 1. Hyattsville, MD: National Center for Health Statistics. 2006. In some cases, to preserve the precision of the description of the changes, we have quoted directly from the report.

2 Martin, et al., 2006.

3 Unless otherwise indicated, this discussion and all direct quotations are drawn from Ventura, S.J., and Bachrach, C.A. (2000), “Nonmarital Childbearing in the United States, 1940-99,” National Vital Statistics Reports; vol. 48, no. 16. Hyattsville, Maryland: National Center for Health Statistics.

4 A paternity acknowledgment is an acknowledgment from a man who is not married to a child’s mother that he is the child’s father.

5 Ventura, S.J., and Martin, J.A. (1993), “Advance Report of Final Natality Statistics, 1990,” Monthly Vital Statistics Reports; vol. 41, no. 9 (supplement). Hyattsville, Maryland: National Center for Health Statistics.

6 With the exception of Connecticut, these changes took place at the beginning of the year cited. The date of Connecticut’s change was June 15.

7 Unless otherwise indicated, all 2003 revisions and reporting issues are based on Martin, J.A., Hamilton, B.E., Sutton, P.D., Ventura, S.J., Menacker, F., Munson, M.L. (2005). “Births: Final data for 2003,” National Vital Statistics Reports; Vol. 54, no. 2. Hyattsville, Maryland: National Center for Health Statistics.

8 Martin, et al. 2006.

9 See Mathews, T.J. (1998), “Smoking During Pregnancy, 1990-96,” National Vital Statistics Reports; vol. 47, no. 10, Hyattsville, Maryland: National Center for Health Statistics and Mathews, T.J. (2001), “Smoking During Pregnancy in the 1990s,” National Vital Statistics Reports; vol. 49, no. 7, Hyattsville, Maryland: National Center for Health Statistics.

10 All changes occurred at the beginning of the year unless otherwise indicated.

11 Source: unpublished tabulation provided by Stephanie Ventura, National Center for Health Statistics.

12 All changes occurred at the beginning of the year unless otherwise indicated.

13 All changes occurred at the beginning of the year unless otherwise indicated.