Adolescent Pregnancy and Childbirth --- United States, 1991--2008

Stephanie J. Ventura, MA

TJ Mathews, MS

Brady E. Hamilton, PhD

Paul D. Sutton, PhD

Joyce C. Abma, PhD

National Center for Health Statistics, CDC

Corresponding author: Stephanie J. Ventura, MA, Division of Vital Statistics, National Center for Health Statistics, CDC, 3311 Toledo Road, Room 7418, Hyattsville, MD 20782. Telephone: 301-458-4547; Fax: 301-458-4033; E-mail: sjv1@cdc.gov.

Giving birth to a child during the adolescent years frequently is associated with long-term adverse consequences for the mother and her child (1--3) that often are attributable in part to fragile family structure and limited social support and financial resources. Compared with infants born to adult women, infants born to adolescent females are at elevated risk for preterm birth, low birth weight, or death during infancy (4--6). An estimated 82% of pregnancies in 2001 among adolescents were unintended (7,8).

To analyze trends and variations in adolescent pregnancy and birth rates, CDC analyzed birth data from the National Vital Statistics System (NVSS) for 1991--2008. Data for 1991--2007 are final; data for 2008 are preliminary (4,6). Data by maternal race/ethnicity are based on information reported by the mother during the birth registration process. Race and ethnicity are reported separately on birth certificates. Birth rates were calculated by using population estimates prepared by the U.S. Census Bureau. Percentage change over time was calculated by comparing the rates for the beginning and end points in each time period. In analyzing differences over time and among groups, only statistically significant differences are noted. Significance testing is based on the z-test at the 95% confidence level (4,6). Additional information is available elsewhere (4,6). Data regarding adolescent pregnancy are not as current or complete as NVSS data regarding adolescent births. Birth data are based on NVSS and are shared with CDC through the Vital Statistics Cooperative Program (VSCP). National data on adolescent pregnancy and childbirth according to such attributes as educational attainment and disability status are not available because this information is not collected consistently and completely in NVSS and the National Abortion Surveillance System. Abortion estimates are from abortion surveillance information collected from the majority of states by CDC; these estimates are adjusted to national totals by the Guttmacher Institute (9). Information on fetal losses is derived from the pregnancy history data collected from multiple cycles of the National Survey of Family Growth (NSFG), conducted by CDC's National Center for Health Statistics (9). The most recent pregnancy estimates that include data on live births, induced abortions, and fetal losses are for 2005 (9).

In 2005, on the basis of available data, approximately 57% of the estimated 740,000 adolescent pregnancies ended in a live birth, 27% ended in an induced abortion, and 16% ended in a fetal loss. Substantial differences exist by race/ethnicity in how adolescent pregnancies are resolved. Pregnancies among non-Hispanic white and Hispanic adolescents are more likely to end in live births and less likely to end in induced abortions than are pregnancies among non-Hispanic black adolescents.

In 2008, the U.S. birth rate for adolescents was 41.5 births per 1,000 females aged 15--19 years (6). Rates vary considerably by race and Hispanic origin. The rate for Hispanic adolescents (77.4 per 1,000 females aged 15--19 years) was approximately five times the rate for Asian/Pacific Islander (A/PI) adolescents (16.2), approximately three times the rate for non-Hispanic white adolescents (26.7) and somewhat higher than the rates for non-Hispanic black adolescents (62.9) and American Indian/Alaska Native (AI/AN) adolescents (58.4) (Table).

During 1991--2005, the birth rate for U.S. adolescents declined one third, from 61.8 per 1,000 females aged 15--19 years in 1991 to 40.5 in 2005. However, the long-term decline was interrupted in 2005--2007, when the adolescent birth rate increased 5%. Preliminary 2008 data indicate that the adolescent birth rate declined 2% during 2007-- 2008.

Trends in birth rates by age group and race/ethnicity indicate that long-term declines during 1991--2005 were experienced by all populations but were somewhat greater for certain groups. During this period, birth rates among adolescents decreased the most (45%) for those aged 15--17 years. The rate for non-Hispanic black adolescents aged 15--17 years decreased 59% to an historic low of 34.9 per 1,000 population in 2005. The rate for Hispanic adolescents aged 15--17 years decreased 30% during 1991--2005, from 69.2 per 1,000 population in 1991 to 48.5 in 2005. Among females aged 18--19 years, the birth rate declined 26% during 1991--2005, and declines of ≥35% were recorded for non-Hispanic black and AI/AN adolescents aged 18--19 years. The increase in birth rates for adolescents aged 15--19 years during 2005--2007 was observed among the majority of racial/ethnic groups. The largest increase (13%) occurred among AI/AN adolescents. Rates for Hispanic adolescents were essentially the same during 2005 and 2007.

During 2007--2008, birth rates for adolescents aged 15--19 years decreased among all racial/ethnic groups. The decline for Hispanic adolescents brought their rate to the lowest ever reported for Hispanics, 77.4 per 1,000 female adolescents in 2008 (Table). Even with the apparent resumption of the decline in adolescent childbearing in 2008, the rate for the United States remains substantially higher than that for other industrialized countries (10).

The most recent adolescent birth data for different Hispanic groups and states are for 2007. Of note, among Hispanic adolescents, birth rates differ across the mother's national origin as well. During 2007, although the overall rate for Hispanic adolescents was 81.8 births per 1,000 adolescent females, the rate for adolescent mothers of Mexican origin was 88.7 per 1,000 adolescent females, and the rate for adolescent mothers of Puerto Rican origin was 67.1 births per 1,000 adolescent females (Table) (4,6). Recent changes in birth rates for adolescent mothers of Mexican and Puerto Rican origin were not statistically significant. Because of limited cell numbers and fluctuations in population estimates, rates cannot be calculated routinely for adolescent mothers of Cuban origin; however, birth rates for adolescents of Cuban origin are relatively low (11).

A recent overview of adolescent birth rates illustrates widespread disparities by state and across population groups (12). Adolescent birth rates were consistently highest in the South and lowest in the Northeast and on the West Coast. These patterns persisted even when rates were examined within population groups. Birth rates for non-Hispanic white, non-Hispanic black, and Hispanic adolescents were uniformly high in the South and consistently low in the Northeast and on the West Coast. Birth rates were also high for non-Hispanic black adolescents in the upper Midwestern states. Similar patterns have been observed since at least 1990 (13,14).

The findings in this report are subject to at least two limitations. First, a full assessment of disparities in adolescent childbearing depends on having a complete understanding of patterns in adolescent pregnancy. In 2005, the most recent year for which complete and comparable data are available on all pregnancy outcomes, 57% of adolescent pregnancies ended in a live birth, 27% in an induced abortion, and 16% in a fetal loss (9). The downward trend in abortions among adolescents from 1991 through 2005 was much stronger than the trend in live births. A full understanding of patterns in adolescent pregnancy requires timely data on abortions and fetal losses as well as live births. Whether the trends in abortions continued downward or reversed in 2006, 2007, and 2008, as they did for live births, is unknown. An estimate by the Guttmacher Institute (using a different methodology) indicates that the adolescent abortion rate increased in 2006 (15). Second, estimating trends and variations in adolescent birth rates depend on having accurate estimates of population changes among age, race, and ethnic subgroups. The rates in this report are computed from population estimates based on the 2000 census (6,11). Rates computed on the basis of other population estimates might indicate different levels and trends. Revised rates incorporating the 2010 census results will be released when the intercensal population estimates become available.

Recently released NSFG data for 2006--2008 indicate limited change from the 2002 NSFG in sexual activity and contraceptive use among adolescents or in attitudes toward sexual activity and childbearing among adolescents (16). Biennial data from CDC's 1991--2009 Youth Risk Behavior Surveys (YRBS) for school-age youth also indicated limited or no change in the majority of these behaviors during recent years (17,18). These NSFG and YRBS findings indicate limited or no recent changes in sexual risk behaviors, compared with previously reported long-term trends of reductions in risky behaviors among adolescents from the early 1990s to the mid-2000s and might provide context for slowing declines in adolescent birth rates during recent years. Further assessment of trends and factors regarding adolescent pregnancy and childbearing, including patterns by race and Hispanic ethnicity, will be possible after data from the next NSFG covering the period 2006--2010 are released later in 2011. During the preceding 2 decades, a broad consensus has existed regarding the goal of preventing teenage pregnancy. Multiple public and private programs have been developed to meet this challenge (2,3,19--22). Community service coordinated with positive youth development behavioral intervention is considered to be an effective method in reducing sexual risk behaviors in adolescents (23). Variations in teenage birth rates reflect differences in interrelated factors, including socioeconomic factors (e.g., education and income, community characteristics, and attitudes among adolescents toward pregnancy and childbearing) that affect sexual activity and contraceptive use (16).

References

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