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Abortion Surveillance --- United States, 2006
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Abstract
Problem/Condition: Since 1969, CDC has conducted abortion surveillance to document the number and characteristics of women obtaining legal induced abortions in the United States.
Reporting Period Covered: 2006.
Description of System: Each year, CDC requests abortion data from the central health agencies of 52 reporting areas (the 50 states, New York City, and the District of Columbia); these data are provided to CDC voluntarily. In 2006, data were received from 49 reporting areas. For the purpose of trend analysis, data were evaluated from the 46 areas that reported data every year during 1996--2006.
Results: For 2006, a total of 846,181 abortions were reported to CDC. Among the 46 areas that provided data consistently during 1996--2006, a total of 835,134 abortions (98.7% of the total) were reported; the abortion rate was 16.1 abortions per 1,000 women aged 15--44 years, and the abortion ratio was 236 abortions per 1,000 live births. During the previous decade (1997--2006), reported abortion numbers, rates, and ratios decreased 5.7%, 8.8%, and 14.8%, respectively; most of these declines occurred before 2001. During the previous year (2005--2006), the total number of abortions increased 3.1%, and the abortion rate increased 3.2%; the abortion ratio was stable.
In 2006, as during the previous decade (1997--2006), women aged 20--29 years accounted for the majority (56.8%) of abortions and had the highest abortion rates (29.9 abortions per 1,000 women aged 20--24 years and 22.2 abortions per 1,000 women aged 25--29 years); by contrast, abortion ratios were highest at the extremes of reproductive age. Adolescents aged 15--19 years accounted for 16.5% of all abortions in 2006 and had an abortion rate of 14.8 abortions per 1,000 adolescents aged 15--19 years; women aged ≥35 years accounted for a smaller percentage (12.1%) of abortions and had lower abortion rates (7.8 abortions per 1,000 women aged 35--39 years and 2.6 abortions per 1,000 women aged ≥40 years). During 1997--2006, the percentage of abortions and the abortion rate increased among women aged ≥35 years but declined among adolescents aged ≤19 years and among women aged 20--29 years.
The majority (62.0%) of abortions in 2006 were performed at ≤8 weeks' gestation; few abortions were performed at 16--20 weeks' gestation (3.7%) or at ≥21 weeks' gestation (1.3%). During 1997--2006, the percentage of abortions performed at ≤8 weeks' gestation increased 11.7%; this increase largely was accounted for by procedures performed at ≤6 weeks' gestation, which increased 66.3%. In 2006, the greatest percentage (87.6%) of abortions were performed by curettage (including vacuum aspiration, sharp curettage, and dilation and evacuation procedures), followed by medical (nonsurgical) abortion (10.6%).
Deaths of women associated with complications from abortions for 2006 are being investigated under CDC's Pregnancy Mortality Surveillance System. In 2005, the most recent year for which data were available, seven women were reported to have died as a result of complications from known legal induced abortions. No reported deaths were associated with known illegal induced abortions.
Interpretation: Among the 46 areas that reported data consistently during 1996--2006, decreases in the total reported number, rate, and ratio of abortions were attributable primarily to reductions before 2001. During 2005--2006, the total number and rate of abortions increased. In 2005, as in the previous years, reported deaths related to abortions occurred only rarely.
Public Health Action: Abortion surveillance in the United States continues to provide the data needed to examine trends in the number and characteristics of women obtaining abortions. Policymakers and program planners can use these data to guide and evaluate efforts to prevent unintended pregnancies.
Introduction
This report is based on abortion data for 2006 provided voluntarily by the central health agencies of 52 reporting areas (the 50 states, the District of Columbia, and New York City) to CDC's National Center for Chronic Disease Prevention and Health Promotion, Division of Reproductive Health. Since 1969, CDC has conducted abortion surveillance to document the number and characteristics of women obtaining legal induced abortions in the United States (1). Following nationwide legalization of abortion in 1973, the total reported number, rate (the number of abortions per 1,000 women aged 15--44 years), and ratio (the number of abortions per 1,000 live births) of abortions increased rapidly, reaching their highest levels in the 1980s. These three measures of abortion subsequently have declined at a slow but steady pace, but with considerable variation across demographic populations (2,3). Continued surveillance is needed to monitor potential changes in the overall incidence of abortion procedures and to guide and evaluate programs for preventing unintended pregnancy in the United States.
Methods
Description of the Surveillance System
CDC requests tabulated data annually from 52 reporting areas (the 50 states, the District of Columbia, and New York City) to document the number and characteristics of women obtaining abortions in the United States. CDC requests data exclusively from the central health agency of each reporting area; before 1998, when CDC was unable to obtain abortion numbers from a central agency, information was requested from the hospitals and other facilities performing abortions in that agency's reporting area.* For the purpose of surveillance, a legal induced abortion is defined as a procedure performed by a licensed physician or by an appropriately licensed advanced practice clinician acting under the supervision of a licensed physician that is intended to terminate a suspected or known intrauterine pregnancy and produce a nonviable fetus at any gestational age (4).† Collection of abortion data is facilitated in most states by the legal requirement for hospitals, facilities, and physicians to report abortions to a central health agency. However, the reporting areas provide this information to CDC on a voluntary basis (5,6). Since 1996, a total of 46 reporting areas have provided a continuous annual record of abortion numbers.§ However, the number of reporting areas providing data on the characteristics of women obtaining abortions and the completeness of the information provided has varied from year to year. For abortions performed in 2006, CDC obtained information from 49 reporting areas (excludes California, Louisiana, and New Hampshire).
Variables Recorded
Each year, CDC's Division of Reproductive Health sends suggested templates to central health agencies for them to compile aggregate abortion numbers according to the age of the woman having an abortion, the estimated gestational age at the time of the procedure, race (white, black, or other), ethnicity (Hispanic or non-Hispanic), type of procedure performed (e.g., curettage or medical), marital status, number of previous live births, number of previous abortions, and state of residence. Cross-tabulation also is requested by gestational age at the time of the procedure (for age, race, ethnicity, and type of procedure), age (for race and ethnicity), and age and race or ethnicity (for marital status). These variables are based on the information included on the standard reporting form developed by CDC's National Center for Health Statistics (NCHS) for the reporting areas to use to collect information on individual women (7). However, because no federal mandate exists that requires reporting areas to provide abortion data to CDC, many areas do not use this suggested reporting form and might not have all the information CDC requests on the characteristics of women obtaining abortions.
To comply with federal standards for the collection of data on race and ethnicity (8), CDC provides alternative data templates for cross-tabulation of aggregate numbers on race and ethnicity and for the addition of certain other racial categories (Asian, Native Hawaiian/Pacific Islander, and American Indian/Alaska Native). Only six reporting areas provided information cross-classified by race and ethnicity, accounting for a total of 8.7% of abortions reported in 2006; among these six areas, data were incomplete (27.1% of cases were returned with unknown values). Consequently, race and ethnicity are presented in this report as separate variables.
Measures of Abortion
Four measures of abortion are presented in this report: 1) the total number of abortions in a given population, 2) the percentage of abortions obtained within a given subpopulation, 3) the abortion rate (i.e., the number of abortions per 1,000 women aged 15--44 years within a given population), and 4) the abortion ratio (i.e., the number of abortions per 1,000 live births within a given population). The total number and percentage of abortions are useful measures for determining the total number of women affected. Abortion rates control for differences in subpopulation size and reflect how likely abortion is within certain populations. Abortion ratios reflect the relative number of pregnancies in a population that end in abortion compared with live births. For the calculation of abortion ratios, data from state health departments were used in surveillance summaries for 1973--1995 to document the number of live births recorded in each reporting area. Starting with the report for 1996, this information has been obtained from NCHS (9). For the calculation of abortion rates, the number of women residing in each reporting area was obtained from U.S. Census Bureau postcensual data (10). Overall abortion rates for women of all ages were calculated from the population of women aged 15--44 years. However, because 94.0% of abortions among adolescents aged <15 years occurred among adolescents aged 13--14 years (as measured in 1988, the last year that NCHS enumerated abortions for this age group) (11), the population of adolescents aged 13--14 years was used as the denominator for this youngest group. Similarly, for women aged ≥40 years, abortion rates were based on the number of women aged 40--44 years.
Data Analysis
This report provides state-specific and overall abortion statistics for 49 reporting areas (excludes California, Louisiana, and New Hampshire). For all 49 areas, state-specific data are reported for 2006. In addition, for the 46 areas that have have provided data for every year since 1996, trends are presented for the entire period during 1996--2006 or for the previous year (2005--2006) and the previous decade (1997--2006)
Although the total number of abortions performed in 2006 was available from 49 reporting areas, the completeness of reporting varied by characteristics and reporting areas. This report describes the characteristics of women from the reporting areas that submitted adequate data (i.e., data categorized in accordance with surveillance variables and with <15% unknown values for a given characteristic). Percentages reported in the text and figures are based on known values; unknown values have been retained in the tables for completeness of reporting. If fewer than five women in a given category obtained an abortion, this value was not displayed in the individual table cells or added to the column totals. However, these small numbers were included in the calculation of summary measures (percentage of total abortions, abortion rates, and abortion ratios).
Most of the data in this report are presented by the state or area in which abortions were performed. In addition, 47 reporting areas¶ also provided the number of abortions by the state or reporting area in which women resided. However, four states (Delaware, Illinois, Maryland, and Wisconsin) reported characteristics for in-state residents but not for out-of-state residents. Four other states (Alaska, Arizona, Iowa, and Massachusetts) provided only the total number of abortions for out-of-state residents, without specifying individual states or areas of residence. As a result, abortion statistics presented in this report by area of residence must be viewed as minimum estimates and might be disproportionately low for areas in which many women travel to obtain abortions in states with incomplete residence reporting.
For the purpose of evaluating trends, linear regression analysis was used to assess the rate of change in overall abortion numbers, rates, and ratios in the United States during 1996--2006. Reporting areas were included in this analysis only if they provided complete data every year during 1996--2006. In addition, the percentage change in abortion statistics was determined for the previous year (2005--2006) and the previous decade (1997--2006). For variables that have been presented only as the percentage of total abortions (procedure type, gestational age, marital status, number of prior abortions, and number of previous births), reporting areas were included in the analysis if they provided complete data for 1997, 2005, and 2006. Summary measures for the subset of areas that reported for all 3 years are presented in the text and might differ from the numbers presented in the tables for all 49 areas that reported for 2006. For variables that have been presented with associated rates and ratios (abortions among all women and abortions by age, race, and ethnicity), data are displayed annually, and reporting areas were included in the analysis only if they provided data every year during 1997--2006; summary measures for these areas are presented in separate tables from the data for all 49 areas that reported for 2006.
Abortion Mortality
CDC has reported data on abortion-related deaths periodically since information on abortion mortality first was included in the 1972 abortion surveillance report (3,12). An abortion-related death is defined as a death resulting from a direct complication of an abortion (legal or illegal), an indirect complication caused by a chain of events initiated by an abortion, or aggravation of a preexisting condition by the physiologic or psychologic effects of abortion (13). An abortion is defined as "legal" if it was performed by a licensed physician or an appropriately licensed advanced practice clinician acting under the supervision of a licensed physician; an abortion is defined as "illegal" if it was performed by any other person. All deaths determined to be related causally to abortion have been classified as abortion-related regardless of the time between the abortion and death.
Since 1987, CDC has monitored abortion-related deaths through its Pregnancy Mortality Surveillance System (PMSS) (14). Additional sources of data for abortion-related deaths include state vital records, maternal mortality review committees, surveys, private citizens and groups, media reports, health-care providers, medical examiners' reports, public health agencies and computerized searches of full-text newspaper/print media databases. For each death that possibly is related to abortion, CDC requests clinical records and autopsy reports. Two clinically experienced medical epidemiologists review these reports to determine the cause of death and whether the death was abortion-related. Each abortion-related death then is categorized by abortion type as legal induced, illegal induced, spontaneous, or unknown type. This report provides data on abortion-related deaths that occurred during 1972--2005; data for 2005 have not been published previously and are the most recent data available. Possible abortion-related deaths that occurred during 2006--2008 are under investigation. Although national case-fatality rates (the number of abortion-related deaths per 100,000 reported legal induced abortions) have been published for 1972--1997, this measure could not be calculated for 1998--2005 with CDC data; a substantial number of abortions have been documented in states that did not report abortion data to CDC (2,15), and thus the total number of abortions was not available as the denominator.
Results
U.S. Totals
Among the 49 areas that provided data for 2006, a total of 846,181 abortions were reported. For the 46 areas that provided data every year during 1996--2006 (excludes Alaska, California, Louisiana, New Hampshire, Oklahoma, and West Virginia), 835,134 abortions (98.7% of the total) were reported; among these 46 consistently reporting areas, the abortion rate was 16.1 abortions per 1,000 women aged 15--44 years, and the abortion ratio was 236 abortions per 1,000 live births (Table 1). During the previous decade (1997--2006), the total number, rate, and ratio of reported abortions declined 5.7%, 8.8%, and 14.8%, respectively. By contrast, during the previous year (2005--2006), the total number of abortions increased 3.1%, and the abortion rate increased 3.2%; the abortion ratio remained stable.
Regression analysis also indicated a general decline during 1996--2006 in abortion numbers, rates, and ratios (Figure 1), but most of this change is attributable to reductions that occurred during 1996--2000. On average during 1996--2000, the number of abortions decreased 20,605 per year, the abortion rate decreased 0.5 abortions per 1,000 women per year, and the abortion ratio decreased 9.7 abortions per 1,000 live births per year. Reductions were much smaller on average during 2001--2006; the number of abortions declined 2,163 per year, the abortion rate declined 0.1 per year, and the abortion ratio declined 3.3 per year.
Occurrence and Residence
Total abortion numbers, rates, and ratios have been tabulated by individual reporting area of occurrence and the residence status of the women who obtained the procedures (Table 2). By area of occurrence, a considerable range existed in the total number of reported abortions (range: seven [Wyoming]--90,157 [New York City]), the rate of abortions (range: 4.2 [Idaho]--48.5 [New York City]),** and the abortion ratio (range: 52 [Idaho]--752 [New York City]).†† Similarly, a considerable range existed by residence status in the total number of reported abortions (range: 275 [Wyoming]--83,220 [New York City]), the rate of abortions (range: 2.7 [Wyoming]--44.7 [New York City]), and the abortion ratio (range: 36 [Wyoming]--694 [New York City]). Given the substantial variation across reporting areas that also occurred in the percentage of abortions obtained by out-of-state residents (range: none [Wyoming]--54.3% [District of Columbia]), abortion rates and ratios calculated by residence status might provide a more accurate reflection of population trends. However, these measures must be viewed with caution because of the variation across reporting areas in methods used to record residence status.
Age
Among women from the 48 areas for which age was reported for 2006, women aged 20--29 years accounted for 417,402 (56.8%) of the 735,187 abortions (excludes 6,063 abortions for women of unknown age) reported by age (Figure 2; Table 3). Women in this age group also had the highest abortion rates (29.9 and 22.2 abortions per 1,000 women aged 20--24 and 25--29 years, respectively). Women at the youngest and oldest age extremes (<15 or ≥40 years) accounted for the smallest percentage of abortions (0.5% and 3.2%, respectively) and had the lowest abortion rates (1.2 and 2.6 abortions per 1,000 women aged <15 and ≥40 years, respectively). This pattern across age groups was stable during the previous decade (1997--2006) among the 44 reporting areas that provided data every year (Table 4). Nonetheless, during 1997--2006, the percentage of overall abortions accounted for by adolescents aged <15--19 years declined (from 20.0% to 17.0%) whereas the percentage among women aged ≥35 years increased (from 10.8% to 12.1%). In addition, although abortion rates declined steadily during 1997--2006 among all women aged ≤29 years, abortion rates in were slightly higher in 2006 than in 2005 for adolescents aged ≥15 years and for women aged 20--29 years (Table 4).
In contrast to abortion rates, abortion ratios for 2006 were highest at the extremes of reproductive age (Figure 2; Table 3). During 1997--2006, abortion ratios declined for all women except adolescents aged <15 years; however, abortion ratios were slightly higher in 2006 than in 2005 for women aged 25--39 years (Table 4).
Adolescents
Among the 46 areas for which age was reported by individual year for 2006, adolescents aged ≤19 years accounted for 116,613 abortions (Table 5). The adolescent abortion rate was 11.0 per 1,000 adolescents, and the adolescent abortion ratio was 358 abortions per 1,000 live births. Adolescents aged 18--19 years accounted for 62.0% of adolescent abortions and had the highest adolescent abortion rates (22.1 and 26.8 abortions per 1,000 adolescents aged 18 and 19 years, respectively). Adolescents aged <15 years accounted for the smallest percentage of adolescent abortions (3.0%) and had the lowest adolescent abortion rate (1.2 abortions per 1,000 adolescents). Among the 41 areas that reported data continuously during the previous decade (1997--2006), this pattern across age groups was similar for each year (Table 6). Although abortion rates among adolescents of all ages declined steadily during 1997--2006, this decline did not continue during 2005--2006 for adolescents aged ≥16 years (Table 6).
Abortion ratios among adolescents generally declined with age and were lowest (310 abortions per 1,000 births) among adolescents aged 19 years (Table 5). Among the 41 reporting areas that provided data for every year during 1997--2006, relative values across age groups again were stable; however, the difference between younger and older adolescents increased, with a comparatively large decline among adolescents aged 18--19 years (Table 6).
Gestational Age
Among women from the 43 areas for which gestational age at abortion was reported for 2006 (Table 7), the majority (62.0%) of abortions were obtained at ≤8 weeks' gestation; only 5.0% of abortions were obtained at ≥16 weeks' gestation (3.7% at 16--20 weeks and 1.3% at ≥21 weeks). Among the 38 reporting areas that provided data for 1997, 2005, and 2006,§§ the percentage of abortions obtained at ≤8 weeks' gestation increased 11.7% (from 55.5% in 1997 to 62.0% in 2006). The percentage of abortions obtained at ≥16 weeks was relatively stable (5.7%, 5.2%, and 5.0% of all abortions in 1997, 2005, and 2006, respectively).
Among women who obtained an abortion in 2006 in the 41 areas that provided the exact week of gestation, 29.6%, 18.2%, and 14.3% obtained their procedure at ≤6, 7, and 8 weeks, respectively (Table 8). Among the 36 areas that provided data in 1997, 2005, and 2006,¶¶ the percentage of abortions obtained at ≤6 weeks' gestation increased 66.3% (from 17.7% of all abortions in 1997 to 29.4% in 2006), resulting in a shift in the gestational age for abortions obtained at ≤8 weeks toward the lower end of the distribution (≤6 weeks gestation).
Method Type
Among the 45 areas for which procedure type was reported for 2006, curettage (including vacuum aspiration, sharp curettage, and dilation and evacuation procedures) accounted for 87.6% of abortions (Table 9); medical (nonsurgical) abortion accounted for 10.6%, and all other methods were uncommon. Among the 39 reporting areas that provided data in 1997, 2005, and 2006,*** curettage declined 11.2% (from 98.2% of all procedures in 1997 to 87.2% in 2006). Most of this decline was accounted for by an increase in the number of medical abortions. Among the 39 areas that provided information on procedure type in 1997, 2005, and 2006, medical abortions accounted for 0.4% of all procedures in 1997, compared with 11.1% in 2006. All other methods accounted for a consistently small percentage of abortions (0.4%--1.7%).
Race
Among women from the 39 areas for which race was reported for 2006, white women (including both Hispanic and non-Hispanic white women) accounted for the largest percentage (55.8%) of abortions; black women accounted for 36.4% and women of other racial groups for 7.8% (Table 10). Black women had higher abortion rates and ratios than white women and women of other races (Table 10). Among the 29 reporting areas that provided data every year during 1997--2006, the percentage of abortions by race changed little; abortions by women in the "other" racial category increased, but the percentage remained low (5.8%--7.7%) (Table 11). Among women from all racial groups, abortion rates and ratios generally declined during 1997--2006, but the abortion rate was higher in 2006 than in 2005; for black women, the abortion ratio was lower in 2006 than in 2005, whereas for white women and women in the "other" racial category, this measure was relatively stable during 2005--2006 (Table 11).
Ethnicity
Among women from the 31 areas for which ethnicity was reported for 2006, Hispanic and non-Hispanic women accounted for 20.1% and 79.9%, respectively, of all abortions (Table 12). Abortion rates were higher among Hispanic women than among non-Hispanic women (21.1 compared with 14.1 abortions per 1,000 women aged 15--44 years, respectively), but abortion ratios among the two ethnic groups were similar (200 and 224 abortions per 1,000 live births, respectively). Among the 19 reporting areas that provided data every year during 1997--2006, the percentage of abortions accounted for by Hispanic women increased 23.6%, whereas the percentage among non-Hispanic women decreased 4.8% (Table 13). In both ethnic groups, abortion rates and ratios generally declined during 1997--2006, but during 2005--2006, abortion rates increased and abortion ratios remained essentially unchanged (Table 13).
Marital Status
Among the 43 areas for which marital status was reported for 2006, 83.5% of all women obtaining abortions were unmarried (Table 14). For the 37 reporting areas that provided data in 1997, 2005, and 2006,††† unmarried women accounted for a slightly higher percentage of abortions in 2006 (83.7%) than in 1997 (81.0%); the percentage was essentially unchanged from 2005 (83.2%).
Previous Live Births and Abortions
Among the 41 areas for which the number of previous live births was reported for 2006, 41.3%, 26.4%, and 32.2% of all women had previously had zero, one, or two or more live births, respectively (Table 15). Among the 36 reporting areas that provided data in 1997, 2005, and 2006,§§§ the change in the distribution of women obtaining abortions by the number of previous live births was minimal (CDC, unpublished data, 2009).
Among the 41 areas for which the number of previous abortions was reported for 2006, the majority of women (55.2%) had not previously had an abortion; 25.5% and 19.2%, respectively, had previously had either one or two or more abortions (Table 16). Among the 34 reporting areas that provided data in 1997, 2005, and 2006,¶¶¶ the change in the distribution of women obtaining abortions by the number of previous abortions was minimal (CDC, unpublished data, 2009).
Age and Marital Status by Race and Ethnicity
In some reporting areas, women of each racial and ethnic category were classified further by age and marital status (Tables 17 and 18). By age, a consistent pattern existed across all racial and ethnic populations: the smallest percentage of abortions (0.4%--0.7%) occurred among adolescents aged <15 years and the largest (29.0%--33.8%) among women aged 20--24 years. By marital status, a consistent pattern also existed across all racial and ethnic populations, with a much higher percentage of abortions occurring among women who were unmarried (68.1%--89.4%) compared with those who were married (10.6%--31.9%).
Weeks of Gestation by Age, Race, Ethnicity, and Type of Procedure
In some reporting areas, women who obtained abortions at different gestational ages also were categorized further by age, race, and ethnicity (Tables 19 and 20). In every subgroup for these three variables, the highest percentage of abortions were obtained at ≤8 weeks' gestation. However, although 42.2% of adolescents aged <15 years and 51.9% adolescents aged 15--19 years obtained an abortion by ≤8 weeks' gestation, 60.5%--69.3% of adult women aged ≥20 years obtained an abortion by this time (Figure 3; Table 19).
For women from the 39 areas for which procedure type was categorized further by week of gestation, at every stage of pregnancy, curettage (including vacuum aspiration, sharp curettage, and dilation and evacuation procedures) accounted for >80% of abortions (Table 21). The smallest percentage of procedures performed by curettage was observed at ≤8 weeks' gestation (82.6%) because of the comparatively high percentage of medical abortions performed at this time (15.9%).
Abortion Mortality
From national PMSS data (14), CDC identified nine deaths for 2005 that were potentially related to abortion. These deaths were identified either by some indication of abortion on the death certificate, by a report from a health-care provider, or from information such as a news or public health report associated with the death. Investigation of these cases indicated that seven of the nine deaths were related to legal abortion and none to illegal abortion (Table 22). Six of the legal abortion--related deaths occurred after a surgical procedure, and one occurred after a medical (nonsurgical) procedure. Two deaths ultimately were determined to be unrelated to the pregnancy and the abortion procedure and hence were not abortion-related by PMSS criteria. Possible abortion-related deaths that occurred during 2006--2008 are under investigation.
Discussion
For 2006, a total of 846,181 abortions were reported in the United States. Among the 46 areas that provided data for every year during 1996--2006, a total of 835,134 abortions were reported. These same 46 areas reported an abortion rate of 16.1 abortions per 1,000 women aged 15--44 years, and an abortion ratio of 236 abortions per 1,000 live births. Compared with 2005, this represents a 3.1% increase in the total number of abortions and a 3.2% increase in the abortion rate. Although this increase in the total number and rate of abortions was the largest observed during the previous decade (1997--2006), the number of live births in the United States and the fertility rate (live births per 1,000 women aged 15--44 years) also increased 3% in 2006, constituting the largest single-year increase in more than 15 years (9). For this reason, the increase in the total number and rate of abortions for 2006 might reflect a general increase in the number of pregnancies of all outcomes (fetal losses, induced abortions, and live births). The stable abortion ratio suggests that this might be the case, but accumulation of surveillance data in subsequent years will be needed to determine whether the 2006 increase in abortions continues without an accompanying increase in fertility.
The increase in the total number and rate of abortions also follows a slowing rate of decline in the incidence of abortion. For the 46 reporting areas that provided a continuous annual record, abortion numbers, rates, and ratios were 5.7%, 8.8%, and 14.8% lower, respectively, for 2006 compared with 1997. However, most of these declines occurred before 2001; by 2000, the rate of decline for all three measures of abortion already had plateaued, and reductions after this time were minimal. A shift over the previous decade in the incidence of abortion might reflect multiple factors, including a decline in the availability of abortion providers (15--18); the adoption of state regulations, including mandatory waiting periods and parental involvement laws (19,20); increasing acceptance of nonmarital childbearing (21,22); and the failure to sustain past reductions in unintended pregnancy associated with improvements in the use of contraception (23--29).
In addition to overall population changes, the findings in this report indicate important age differences in abortion trends. Because women aged 20--29 years had the majority of abortions (>55%) during 1997--2006, they accounted for most of the overall changes in abortion rates. Conversely, women aged ≥35 years accounted for only a small percentage of abortions, but their abortion rates increased slowly over this entire period. This slow but persistent increase suggests that unintended pregnancy might be observed increasingly among older women as they delay childbearing and continue to use reversible contraceptive methods to retain their fertility options (2,26). Finally, this report provides data on adolescent abortion trends that will be important for evaluating recent changes in adolescent pregnancy and births. Although adolescent pregnancy and birth rates declined by approximately one third during 1991--2005 (30,31), adolescent birth rates increased 5.0% during 2005--2007, with most of this change occurring during 2005--2006 (9,32). A notable finding of this report is that adolescent abortion rates also increased during 2005--2006 after several years of decline. These concurrent trends suggest that the recent increase in adolescent births can be attributed to an increase in adolescent pregnancies rather than a simple shift in the percentage of pregnancies resulting in live births. However, the findings in this report also suggest that some of the increase in adolescent births might be attributable to an increasing tendency for adolescents to continue their pregnancies. The increase in adolescent birth rates exceeded the increase in adolescent abortion rates for 2006.**** In addition, in contrast to adolescent abortion rates, adolescent abortion ratios continued to decline during 2005--2006. Ongoing surveillance is needed to evaluate these trends fully.
The findings in this report on race and ethnicity reflect disparities in abortion that have been well-documented and observed for many years (2,3,31,33,34). Comparatively high abortion rates and ratios among black women have been attributed to high unintended pregnancy rates and a high percentage of unintended pregnancies ending in abortion (23). This report indicates that abortion rates and ratios declined during 1997--2006 among women of all racial groups. However, although the decline in abortion ratios among black women continued during 2005--2006, this decline was not observed among women of other races. Data from subsequent years will be needed to assess whether this is a sustained trend.
The findings provided in this report also suggest that the percentage of abortions accounted for by Hispanic women increased during 1997--2006. However, this likely reflects the fact that Hispanic women account for a growing proportion of the United States population (35). Differences in abortion rates and ratios between Hispanic and non-Hispanic women presented in this report are difficult to interpret because the non-Hispanic category includes women from white, black, and other racial populations. Additional efforts to obtain more complete data on race and ethnicity will be attempted for future surveillance reports.
The findings presented in this report indicate that more women are obtaining abortions earlier in gestation, when the risks for complications are lowest (36). Among the areas that reported data consistently during 1997--2006, abortions obtained at ≤8 weeks' gestation increased 11.7%, accounting for 62.0% of all procedures in 2006 compared with 55.5% in 1997. A small but stable percentage of abortions (5.0%--5.7%) were performed at ≥16 weeks' gestation. Even among early-term abortions (≤8 weeks' gestation), a progressive shift to earlier stages of pregnancy occurred: although the percentage of abortions obtained at ≤6 weeks' gestation increased 66.3%, the number performed during the eighth week declined 26.8%. Nonetheless, although a general trend existed for women to obtain abortions at earlier stages of gestation, adolescents were less likely than adult women to obtain an abortion by ≤8 weeks' gestation. Adolescents might seek abortion later in pregnancy because they often take longer to suspect and confirm they are pregnant (37). Additionally, in states with parental involvement laws, adolescents might need more time to receive court approval for obtaining an abortion without parental involvement or to make arrangements to travel to another state. Adolescents approaching age 18 years also have been reported to wait until they are old enough to obtain an abortion without parental involvement (38,39).
The shift in abortion to earlier stages of gestation, although not observed equally in all age groups, reflects changes in the types of procedures being used. Curettage has remained the most common method for performing abortions. Although for many years this procedure has been performed after the initial weeks of gestation, the development of highly sensitive pregnancy tests and transvaginal ultrasonography increasingly has allowed clinicians to diagnose pregnancy and confirm its effective termination at ≤6 weeks' gestation (40--43). In addition, the increasing use of medical abortion has contributed to the rising percentage of abortions performed early in gestation. During 1997--2006, the use of medical abortion among the subset of areas that reported data every year increased from 0.4% of all abortions in 1997 to 11.1% in 2006; among all of the areas that reported procedure type by gestational age for 2006, medical abortion accounted for 15.9% of all cases performed at ≤8 weeks' gestation.
The annual number of deaths associated with known legal abortions was more than two thirds lower on average in the early 2000s than it was in the early 1970s. In 2005, seven women died from causes known to be associated with legal abortions, and none died as a result of known illegal abortions. CDC data cannot be used to calculate national case-fatality rates for 1998--2005 because certain states (four during 1998--1999 and three during 2000--2005), including California, did not report data. Because a substantial number of abortions have been documented in California (2,15), CDC data cannot be used to approximate the total number of abortions as the denominator.
Of the seven deaths associated with legal abortions that were identified in 2005, one occurred after a medical (nonsurgical) abortion procedure. This case has been described previously (44).
Limitations
The findings in this report are subject to at least four limitations. First, because reporting requirements are established by the reporting areas, variation exists in the collection of data. Not all reporting areas use CDC's standard reporting form (7), and many reporting areas do not collect all the information CDC requests on the characteristics of women obtaining abortions (e.g., age, race, and ethnicity); similarly, many reporting areas do not specifically include medical abortion as one of the potential methods for terminating a pregnancy (5,6). Although missing demographic information might reduce the extent to which the statistics in this report represent all women in the United States, three nationally representative surveys of women obtaining abortions in 1987, 1994--1995 and 2001--2002 have produced distributions of characteristics similar to the distributions reported by CDC for the relevant years (2,33,34,45). Conversely, because the number of reporting areas specifically requesting information on medical abortion increased considerably during 1997--2006 (5,6), the numbers presented in this report might not accurately represent trends in the use of this method for performing abortions.
Second, as a result of the variation in reporting requirements, the number of abortions reported annually by CDC is lower than the actual total number of abortions performed in the United States. Although most states have laws mandating the collection of abortion data, in some reporting areas, information is provided to the central health agency on a voluntary basis (5,6). Consequently, the number of abortions reported by CDC consistently has been ≥11.0% lower than the numbers obtained by the Guttmacher Institute through active survey techniques (2,46). In addition, although some areas undoubtedly are unable to count all abortions that occur in their jurisdictions, others provide no numbers at all. Because of these nonreporting areas, since 1998, the number of abortions reported to CDC has been only 65%--69% of the number counted by the Guttmacher Institute (2).
Third, abortion data are compiled and reported to CDC by the central health agency of the reporting area in which the abortion was performed rather than the area in which the woman resided. This inflates abortion statistics for areas in which a high percentage of abortions are obtained by out-of-state residents and undercounts procedures for states with limited abortion services, more stringent legal requirements for obtaining an abortion, or convenient geographic proximity to another state.
Finally, because reporting areas provide CDC with aggregate numbers rather than individual-level records, joint analysis of many points of interest (e.g., age, race, and ethnicity) is precluded; moreover, adjustments for socioeconomic status cannot be made without data on education or income.
Public Health Actions
Ongoing national surveillance of abortion is useful for multiple reasons. Ongoing abortion surveillance is needed to guide and evaluate programs aimed at preventing unintended pregnancies. Although pregnancy intentions are complex and difficult to assess (47--52), the number of abortions provides a concrete measure of the number of unwanted pregnancies. In addition, routine national surveillance of abortion is needed to assess changes in clinical practice patterns (e.g., types of procedures being used and the gestational age at which procedures are performed). Finally, statistics on the number of pregnancies ending in abortion can be used in conjunction with data on births and fetal deaths to estimate pregnancy numbers accurately and determine rates for a variety of outcomes (e.g., adolescent pregnancy rates) (31).
Since 1973, the National Survey of Family Growth (NSFG) has been a principle source of information on factors affecting patterns of sexuality, contraceptive use, and pregnancy intentions in the United States (53). According to the 2002 NSFG, the most recent source of national data on pregnancy intentions, 48% of all pregnancies in the United States are unintended (23). Moreover, calculations based on NSFG data suggest unintended pregnancy underlies nearly all abortions,†††† and one fifth of all pregnancies in the United States end in abortion (31). Providing women with the knowledge and resources necessary to make decisions about their sexual behavior and use of contraception can help women avoid unintended pregnancies and thus reduce the number of abortions performed in the United States. However, efforts to reduce unintended pregnancy have been challenging. NSFG data suggest that unintended pregnancy rates declined during 1982--1995 in conjunction with an increase in the proportion of women at risk for unintended pregnancy§§§§ who were practicing contraception (24,26,27). However, findings from the 2002 NSFG suggested that declines in unintended pregnancy reached a plateau (23). This might be attributable to multiple factors, including
- a 40% increase during 1995--2002 in contraceptive nonuse among women at risk for unintended pregnancy (26),
- only modest improvements in the effective use of the most widely adopted forms of reversible contraception (e.g., injectibles, oral contraceptives, and male condoms, which had a 7%, 9%, and 17% probability of pregnancy, respectively, within the first 12 months of typical use) (25), and
- minimal use of the most effective forms of reversible contraception (e.g., contraceptive implants and intrauterine devices, which were used by <1.5% and <2.5% of all women practicing contraception, respectively) (26).
Because the total number of unintended pregnancies and abortions is similar for the comparatively small group of women who do not use contraception and the much larger group of women who use contraception incorrectly or inconsistently (23,54,55), broader and more effective use of contraception will be needed. Findings from the 2006--2008 NSFG, scheduled for release in late 2009 (56), can help to target efforts for improving contraceptive use, thereby reducing the number of unintended pregnancies and thus the number of legal induced abortions in the United States.
Acknowledgment
Kristi Seed, Division of Reproductive Health, National Center for Chronic Disease Prevention and Health Promotion, CDC, assisted with the tables.
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