Our analyses of births to unmarried women were conducted using data from the 2004 natality file produced by the National Center for Health Statistics (NCHS 2006). The data set includes records for all 4.1 million births registered in the United States in 2004, collected from information reported on state birth certificates. The 2004 data were the most recent available. We analyzed the data set online using the interactive VitalStats website.
Births can be classified by either the state where the birth occurred or the mother’s state of residence. For this analysis, we classified births by the mother’s state of residence, because this information is more relevant for marriage program operators and policymakers working with their state populations. Regional estimates were calculated for the nine standard geographic divisions defined by the U.S. Census Bureau (see Figure B.1).
The following measures of maternal demographic characteristics were used in our analyses:
- Marital Status. The mother’s marital status is reported on state birth certificates everywhere except Michigan and parts of New York. In areas where marital status is not reported, NCHS identifies births to unmarried women using other information reported on the birth certificate, primarily the paternity acknowledgement used to enforce child support obligations. NCHS also classifies births as nonmarital if the father’s name is missing from the birth certificate.
- Age. Mother’s age is reported in the data set for all 50 states. To simplify the presentation of results, we collapsed this variable into three broad age groups: (1) less than 18 years, (2) 18 to 29 years, and (3) over 30 years. We chose 18 years as the cut-off between the two youngest age groups because healthy marriage programs for new unmarried parents generally do not serve minors.
- Race/Ethnicity. We used a combination of two variables to measure the mother’s racial/ethnic background. The first variable classifies mother’s race into one of the following four categories: (1) white, (2) African American, (3) American Indian, or (4) Asian or Pacific Islander. A separate variable indicates whether the mother is Hispanic. We combined these variables to create broader categories for four main racial/ethnic groups: (1) non-Hispanic whites, (2) non-Hispanic African Americans, (3) non-Hispanics from any other racial group, and (4) Hispanics of any race. For states with large American Indian, Asian, or Pacific Islander populations, we also provide separate estimates for non-Hispanics in these groups. For example, for the following five states we report separate estimates for Asians or Pacific Islanders: Alaska, California, Hawaii, Minnesota, and Washington. In addition, for the following eight states we report separate estimates for American Indians: Alaska, Arizona, Montana, New Mexico, North Dakota, Oklahoma, South Dakota, and Wyoming.
- Education Level. The variable used to measure mother’s education level varies by state. Some states report the mother’s highest grade level completed (for example, 8th grade or 12th grade), whereas other states report the highest degree she completed (for example, a high school diploma or bachelor’s degree). To make these variables more comparable across states, we combined the different categories into three mutually exclusive groups: (1) women who had not finished high school, (2) women who had graduated from high school but did not have a college degree, and (3) women with four-year college degrees. Information on mother’s education level is reported in the data set for all states except Florida and New Hampshire. In 2004, Florida and New Hampshire revised the education question included on their birth certificates, so the data for these states are not consistent throughout the year. Florida and New Hampshire are also excluded from the national and regional benchmark estimates reported in the tables.
- Geographic Area. Within the records for each state, the data set identifies the mother’s county of residence for those living in counties with populations of 100,000 or more. For confidentiality reasons, county of residence is not identified for mothers living in smaller counties. Using this information, we calculated subgroup estimates for the one or two largest counties in each state, as well as a combined estimate for the state’s smaller counties. We do not report any subgroup estimates for Wyoming, because all of the counties in that state have fewer than 100,000 people.
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