Abortion Surveillance --- United States, 2004

Lilo T. Strauss, MA, Sonya B. Gamble, MS, Wilda Y. Parker,
Douglas A. Cook, MBIS, Suzanne B. Zane, DVM, Saeed Hamdan, MD, PhD
Division of Reproductive Health
National Center for Chronic Disease Prevention and Health Promotion

The material in this report originated in the National Center for Chronic Disease Prevention and Health Promotion, Janet Collins, PhD, Director; and the Division of Reproductive Health, John Lehnherr, Acting Director.
Corresponding address: CDC/National Center for Chronic Disease Prevention and Health Promotion/Division of Reproductive Health, 1600 Clifton Rd., NE, MS K-21, Atlanta, GA 30333. E-mail: [email protected].

Abstract

Problem/Condition: CDC began abortion surveillance in 1969 to document the number and characteristics of women obtaining legal induced abortions.

Reporting Period Covered: This report summarizes and describes data voluntarily reported to CDC regarding legal induced abortions obtained in the United States in 2004.

Description of System: For each year since 1969, CDC has compiled abortion data by state or area of occurrence. During 1973--1997, data were received from or estimated for 52 reporting areas in the United States: 50 states, the District of Columbia, and New York City. In 1998 and 1999, CDC compiled abortion data from 48 reporting areas. Alaska, California, New Hampshire, and Oklahoma did not report, and data for these states were not estimated. During 2000--2002, Oklahoma again reported these data, increasing the number of reporting areas to 49; for 2003 and 2004, Alaska again reported and West Virginia did not, maintaining the number of reporting areas at 49.

Results: A total of 839,226 legal induced abortions were reported to CDC for 2004 from 49 reporting areas, representing a 1.1% decline from the 848,163 legal induced abortions reported by 49 reporting areas for 2003. The abortion ratio, defined as the number of abortions per 1,000 live births, was 238 in 2004, a decrease from the 241 in 2003. The abortion rate was 16 per 1,000 women aged 15--44 years for 2004, the same since 2000. For the same 47 reporting areas, the abortion rate remained relatively constant during 1998--2004. In 2003 (the most recent years for which data are available), 10 women died as a result of complications from known legal induced abortion. No death was associated with known illegal abortion.

The highest percentages of reported abortions were for women who were known to be unmarried (80%), white (53%), and aged <25 years (50%). Of all abortions for which gestational age was reported, 61% were performed at <8 weeks' gestation and 88% at <13 weeks. From 1992 (when detailed data regarding early abortions were first collected) through 2004, steady increases have occurred in the percentage of abortions performed at <6 weeks' gestation, except for a slight decline in 2003. A limited number of abortions were obtained at >15 weeks' gestation, including 4.0% at 16--20 weeks and 1.4% at >21 weeks. A total of 35 reporting areas submitted data stating that they performed and enumerated medical (nonsurgical) procedures, making up 9.7% of all known reported procedures from the 45 areas with adequate reporting on type of procedure.

Interpretation: During 1990--1997, the number of legal induced abortions gradually declined. When the same 47 reporting areas are compared, the number of abortions decreased during 1996--2001, then slightly increased in 2002 and again decreased in 2003 and 2004. In 2000 and 2001, even with one additional reporting state, the number of abortions declined slightly, with a minimal increase in 2002 and a further decrease in both 2003 and 2004. In 2003, as in the previous years, deaths related to legal induced abortions occurred rarely.

Public Health Action: Abortion surveillance in the United States continues to provide the data necessary for examining trends in numbers and characteristics of women who obtain legal induced abortions and to increase understanding of this pregnancy outcome. Policymakers and program planners use these data to improve the health and well-being of women and infants.

Introduction

CDC began conducting abortion surveillance in 1969 to document the number and characteristics of women obtaining legal induced abortions. This report is based on abortion data for 2004, provided voluntarily to CDC's National Center for Chronic Disease Prevention and Health Promotion (NCCDPHP), Division of Reproductive Health.

Methods

For 2004, CDC compiled data that were voluntarily provided from 49 reporting areas in the United States: 47 states (excluding California, New Hampshire, and West Virginia), the District of Columbia (DC), and New York City (NYC). Legal induced abortion was defined as a procedure, performed by a licensed physician or someone acting under the supervision of a licensed physician, that was intended to terminate a suspected or known intrauterine pregnancy and to produce a nonviable fetus at any gestational age (1,2). The total number of legal induced abortions was available from all reporting areas; however, not all areas collected data on some or all characteristics of women who obtained abortions, and the availability of such data varied by reporting area.

Data on the age of women who obtained abortions were collected and reported adequately (i.e., categorized in accordance with surveillance variables and with <15% unknown values) by 48 reporting areas (46 states [excluding California, Florida, New Hampshire, and West Virginia], DC, and NYC), representing 88% of all reported procedures. Data on ethnicity were collected and reported adequately by only 27 reporting areas, representing 57% of all reported procedures. The findings in this report reflect characteristics of women only from reporting areas that submitted adequate data for the characteristics being examined. For the majority of state tables, the percentage data include a category for unknown values, and the percentage known to be in each category might be a slight understatement of the true percentage in that category because of missing information. However, for trend data, out-of-area residents, adolescent ages, and two-characteristics tables, percentages presented are based on known values only.

For the 49 reporting areas, data on the number of women obtaining legal induced abortions were provided by the central health agency.* These agencies provided data on numbers of abortions and characteristics of women obtaining abortions by the reporting area in which the abortion was performed (i.e., state of occurrence). For the majority of reporting areas, abortion totals also were available by the woman's state or area of residence. However, three states (Delaware, Maryland, and Wisconsin) reported characteristics only for residents who obtained abortions in the state but not for women from out-of-state. Three states (Florida, Kentucky, and Louisiana) did not report abortion totals by resident status, and four 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.

This report provides overall and state-specific abortion statistics. For all characteristics for which birth or population data were available, abortion ratios (number of abortions per 1,000 live births) or abortion rates (number of abortions per 1,000 women in a given age group) are provided. Beginning with 1996 data, abortion ratios were calculated by using the number of live births to residents of each area from birth data reported to CDC's National Center for Health Statistics (NCHS); these numbers were previously received from state health departments. The population data used for calculating most recent abortion rates were obtained from the U.S. Census Bureau postcensual data (3).

Women aged 20--39 years who obtained legal induced abortions were categorized by 5-year age groups, adolescents aged 15--19 years were categorized by single years of age, and the relatively few abortions at age <15 years or >40 years each had one group. Abortion numbers, ratios, and rates are presented by age group. Because 94% of abortions among adolescents aged <15 years occurred among those aged 13--14 years in 1988 (the latest year for which this information is known) (4), the population of adolescents aged 13--14 years was used as the denominator for calculating abortion rates for adolescents aged <15 years. Rates for women aged >40 years were based on the number of women aged 40--44 years. However, rates for all females who obtained abortions were based on the population of females aged 15--44 years.

Race was categorized by three groups: white, black, and all other races. Other races included Asian or Pacific Islander, American Indian, Alaska Native, and women classified as "other" race. Ethnicity was categorized as either Hispanic or non-Hispanic. As in previous reports, race and ethnicity were provided as separate variables, and abortions were not cross-classified by race and ethnicity. Abortion numbers, ratios, and rates are presented by both race and ethnicity.

Despite efforts to collect and provide a cross-classification of race and ethnicity for the 2001 report in compliance with OMB Directive 15, which specifies federal standards for the collection of data on race and ethnicity (5), only 28 states (accounting for 39% of the total number of reported abortions) were able to provide adequate data for use of the recommended race categories. Eleven states could not adequately break down the data by ethnicity. Moreover, three recommended racial categories (Asian, Native Hawaiian or other Pacific Islander, and American Indian or Alaskan Native) had to be combined into one category of "other" to accommodate overlapping categories provided by multiple states. For these reasons, no additional information regarding race or ethnicity was obtained as a result of unavailable data. Therefore, further efforts to collect cross-classified race and ethnicity will not be attempted unless additional states start collecting such data.

Marital status was reported as either married (including women who were married or separated) or unmarried (including those who were never married, widowed, or divorced). Abortion numbers and ratios are presented by marital status.

Gestational age (in weeks) at the time of abortion was categorized as <6, 7, 8 and <8, 9--10, 11--12, 13--15, 16--20, and >21. Weeks of gestation were estimated in 11 reporting areas as the time elapsed since the woman's most recent menstrual period. For 27 other states, gestational age was reported on the basis of the physician's estimate (data from the clinical examination, including ultrasound results). For the remaining six states, gestational age was derived from a combination of the physician's estimates and the time elapsed since the woman's most recent menstrual period. Of the 44 areas that reported adequate data on weeks of gestation at the time of abortion, 41 also reported abortions performed at <8 weeks' gestation separately for those performed at <6, 7, and 8 weeks' gestation. Abortion numbers are presented by gestational age.

The type of abortion procedure was categorized as curettage (including suction and/or sharp curettage at any gestational age) and reported separately for <12 weeks and >12 weeks, intrauterine instillation, medical (nonsurgical) abortion (methotrexate and misoprostol or mifepristone and misoprostol were reported for abortions performed at <8 weeks gestation; vaginal prostaglandins were primarily reported for abortions performed at later weeks of gestation), and procedures described as other (including hysterectomy and hysterotomy).

CDC has reported data on abortion-related deaths periodically since these deaths were first included in the Abortion Surveillance Report in 1972 (6,7). An abortion-related death was defined as a death resulting from a direct complication of an abortion, an indirect complication caused by the chain of events initiated by abortion, or aggravation of a preexisting condition by the physiologic or psychologic effects of the abortion (1,2). All deaths causally related to induced abortion are classified as induced abortion-related regardless of the duration of time between the abortion and the death.

Sources of data for abortion-related deaths included national and 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 possibly related to an induced abortion or an abortion of unknown type, clinical records and autopsy reports were requested and reviewed by two clinically experienced medical epidemiologists to determine the cause of death and whether the death was abortion related. Each abortion-related death was then categorized by abortion type as legal induced, illegal induced, spontaneous, or unknown type. Data on abortion-related deaths for 1972--2003 are provided in this report. The 2003 data have not been published previously and are the most recent data available. National case-fatality rates were calculated as the number of known legal induced abortion-related deaths per 100,000 reported legal induced abortions. Case fatality rates for 1972--1997 are provided in this report. Case fatality rates for 1998--2003 cannot be calculated because a substantial number of abortions occur in the nonreporting states; as a result, the total number of abortions (the denominator) is unknown.

Results

Overall, the annual number of legal induced abortions in the United States increased gradually from 1973 until it peaked in 1990, and it generally declined thereafter (Figure 1). In 2004, a total of 839,226 legal induced abortions were reported to CDC by 49 reporting areas. This change represents a 1.1% decline from 2003, for which 49 areas reported 848,163 legal induced abortions (Tables 1 and 2).

The national legal induced abortion ratio increased from 196 per 1,000 live births in 1973 (the first year that 52 areas reported) to 358 per 1,000 in 1979 and remained nearly stable through 1981 (Figure 1; Table 2). The ratio peaked at 364 per 1,000 in 1984 and since then has demonstrated a generally steady decline. In 2004, the abortion ratio was 238 per 1,000 in 49 reporting areas and 239 for the same 47 reporting areas for which data were available since 1998 (Table 2).

The national legal induced abortion rate increased from 14 per 1,000 women aged 15--44 years in 1973 to 25 per 1,000 in 1980. The rate remained stable, at 23--24 per 1,000 during the 1980s and early 1990s and at 20--21 per 1,000 during 1994--1997. The abortion rate remained unchanged at 17 per 1,000 during 1998--1999 and at 16 per 1,000 during 2000--2002 both overall and in the same 47 reporting areas. During 2003--2004, the abortion rate remained unchanged overall at 16 per 1,000, decreased to 15 per 1,000 in 2003, and to 16 in 2004 in the 47 reporting areas.

The numbers, ratios, and rates of reported legal induced abortions are presented by area of residence and by area of occurrence (Table 3). In 2004, the highest number of reported legal induced abortions occurred in Florida (91,710), NYC (91,673), and Texas (74,801); the fewest^† occurred in Wyoming (12), South Dakota (814), and Idaho (963) (Table 3). The abortion ratios by state or area of occurrence ranged from 43 per 1,000 live births in Idaho to 770 per 1,000 in NYC. Among women aged 15--44 years, rates by occurrence ranged from three per 1,000 women in Idaho to 30 per 1,000 in New York. These ratios and rates should be viewed with consideration of the sizable variation by state in the percentage of abortions obtained by out-of-state residents. In 2004, approximately 8% of reported abortions were obtained by out-of-state residents (range: from 0.2% [in Alaska] to 53% [in DC]) (Table 3). Data by state of residence are incomplete because three states (California, New Hampshire, and West Virginia) did not report any data on abortion, and seven states (Alaska, Arizona, Florida, Iowa, Kentucky, Louisiana, and Massachusetts) did not provide data concerning the residence status of all women obtaining abortions in their state. Thus, ratios and rates by state of residence should be viewed with caution because of the substantial variation in completeness of reporting of residence information.

Women known to be aged 20--24 years obtained 33% of all abortions for which age was adequately reported. Adolescents reported as age <15 years obtained <1.0% of all abortions in the 48 areas that reported age. Among the 48 reporting areas, age was not reported for 0.5% of patients; however, this percentage ranged from 0.0% (in 18 areas) to 4.5% (Nevada) (Table 4). Abortion ratios were highest for adolescents aged <15 years (762 per 1,000 live births) and lowest for women aged 30--34 years (143 per 1,000) (Figure 2; Table 4). In contrast to abortion ratios, among females for whom age was reported, abortion rates were highest for women aged 20--24 years (30 per 1,000 women) and lowest for females at the extremes of reproductive age (1 per 1,000 adolescents aged 13--14 years and 3 per 1,000 women aged >40 years) (Table 4). Among women aged <20 years (46 reporting areas), the percentage of abortions obtained increased with age (Table 5); however, the abortion ratio was highest for adolescents aged <15 years^§ (773 per 1,000 live births) and lowest for women aged 19 years (325 per 1,000). Conversely, the rates of abortions were lowest (1 per 1,000) for adolescents aged <15 years and highest (27 per 1,000) for women aged 19 years (Table 5).

Abortion trends by age indicate that since 1973, abortion ratios have been higher for adolescents aged <15 years than for any other age group (Figure 3). For females aged <19 years and those aged >40 years, the abortion ratio generally increased from 1974 through the early 1980s and declined thereafter. The abortion ratio for women aged 20--34 years (those with the highest fertility rates) has declined slightly since the mid-1980s. The abortion ratio for women aged 35--39 years has declined gradually over time (Figure 3).

In 2004, for women from areas where weeks of gestation at the time of abortion were adequately reported (44 reporting areas), 61% of reported legal induced abortions were known to have been obtained at <8 weeks' gestation and 87% at <12 weeks (Table 6). Overall (41 reporting areas), 28% of abortions were known to have been performed at <6 weeks' gestation, 18% at 7 weeks, and 15% at 8 weeks (Table 7). Few reported abortions were known to have occurred after 15 weeks' gestation: 3.7% at 16--20 weeks and 1.3% at >21 weeks.

For women whose type of procedure was adequately reported, 87% of abortions were known to have been performed by curettage (which includes dilatation and evacuation [D&E]) and 0.6% by intrauterine instillation (Table 8). A total of 35 reporting areas submitted information regarding performance of medical (nonsurgical) procedures^¶ (hereafter referred to as medical abortion). Known medical abortions make up approximately 10% of all procedures reported from the 45 areas with adequate reporting on type of procedure. In addition, two areas that did not collect data separately for medical abortions on their abortion reporting form included medical abortions in the "other" category. For the 35 areas that reported medical abortions separately, 66,033 medical abortion procedures were performed in 2004. Eight states reported that no medical abortions were performed in 2004 but did not specify whether such abortions were available. For the 32 reporting areas that reported one or more medical abortion for both 2003 and 2004, the data reflect an increase of 17%, from 54,703 in 2003 to 63,975 in 2004 (8). The extent to which the 66,033 medical abortions reported to CDC for 2004 represent the use of this procedure in all reporting areas is unknown. Hysterectomy and hysterotomy were included in the "other" procedure category and were used in <0.01% of all abortions.

In the 38 reporting areas for which race was provided, classified according to the same categories used in previous years, approximately 53% of women who obtained legal induced abortions were white; 35%, black; and 8%, other; race was not known for 4% (Table 9). The abortion ratio for black women (472 per 1,000 live births) was 2.9 times the ratio for white women (161 per 1,000), and the ratio for women of the nonhomogeneous "other" race category (330 per 1,000) was 2.0 times the ratio for white women. The abortion rate for black women (28 per 1,000 women) was 2.9 times the rate for white women (10 per 1,000), and the abortion rate for women of other races (22 per 1,000 women) was 2.2 times the rate for white women.

A total of 27 reporting areas had separate and adequate data^** on the ethnicity of women who obtained legal induced abortions (Table 10). The percentage of abortions known to have been obtained by Hispanic women in these reporting areas was 19% overall (range: from 0.6% [in Mississippi] to 50% [in New Mexico]). For Hispanic women in these reporting areas, the abortion ratio was 211 per 1,000 live births, and the abortion rate was 26 per 1,000 women. However, only 46% of Hispanic women in the United States resided in these reporting areas.

Because reporting areas provide data voluntarily, they are not required to use the 31 race/ethnicity categories mandated by the Office of Management and Budget (OMB) for federally funded data collection. Although providing data cross-classified by race and ethnicity would be helpful, collecting these data will not be continued unless a substantial number of states change their race/ethnicity questions in this direction.

For women whose marital status was adequately reported (41 reporting areas), 80% of women who obtained abortions were known to be unmarried (Table 11). The abortion ratio for unmarried women (510 per 1,000 live births) was 8.4 times that for married women (61 per 1,000).

For women who obtained legal induced abortions and for whom data on previous live births were adequately reported (41 reporting areas), 40% were known to have had no previous live births, and 32% had had two or more previous live births (Table 12). The abortion ratio was highest for women who had three previous live births (274 per 1,000 live births) and lowest for those who had one previous live birth (190 per 1,000).

For women who obtained an abortion and whose number of previous abortions were adequately reported (41 reporting areas), 54% were reported to have obtained an abortion for the first time, and 19% were reported to have had at least two previous abortions (Table 13).

For women whose age and race were known (36 reporting areas), the differences in age distributions of white and black women were relatively small. White women had a slightly higher percentage of abortions in the youngest (<19 years) and oldest (>35 years) age groups compared with black women (17.3% versus 16.9% and 12.5% versus 10.0%, respectively), whereas women of other races who had abortions tended to be older (Table 14). For women whose marital status and race were both known (32 reporting areas), the percentage of reported abortions among black women who were unmarried was higher (89%) than that among white women (81%) or among women of other races (64%). Among older (aged >35 years) women obtaining abortions whose age and ethnicity were known and reported adequately (26 reporting areas), the percentage of abortions obtained by non-Hispanic women (12%) exceeded that for Hispanic women (10%) (Table 15). Among women whose marital status and ethnicity were known and reported adequately (25 reporting areas), the percentage of reported abortions obtained by unmarried women was slightly higher for non-Hispanic women (83%) than for Hispanic women (82%) (Table 15).

Approximately 88% of all abortions for which gestational age at the time of abortion was known and reported adequately (44 reporting areas) were obtained at <12 weeks' gestation (Table 1). The percentage of women who obtained an abortion at <8 weeks' gestation increased with age (Figure 4; Table 16). This association was most pronounced for abortions obtained at <6 weeks' gestation (41 reporting areas) (Table 17). The percentage of women who obtained an abortion decreased with age for women who obtained an abortion at 9--10, 11--12, and 13--15 weeks' gestation, through age 30--34 years at 16--20 weeks' gestation, and through age 25--29 years at >21 weeks' gestation (Table 16). Among women with adequately reported race and weeks of gestation (33 reporting areas), white women and women of other races were more likely than black women to obtain abortions at <6 and 7 weeks' gestation, but less likely after that (Tables 16 and 17). Among women with adequately reported known ethnicity and weeks of gestation (25 reporting areas), the difference in timing of their abortions between Hispanic and non-Hispanic women was minimal (<4.3%) at any gestational age (Tables 16 and 17).

For women whose type of procedure and weeks of gestation were known and adequately reported (40 reporting areas), approximately 89% of reported abortions obtained at <15 weeks' gestation were performed by using curettage (primarily suction procedures) (Table 18). Approximately 93% of the 68,099 reported medical abortions were performed at <8 weeks' gestation, representing 14.2% of all abortions performed at <8 weeks' gestation. At >16 weeks' gestation, medical abortions (n = 888) made up 2.2% of all abortions. Medical abortions constituted 1.5% of procedures performed in the 9--15 weeks' gestation range. Intrauterine instillation involving use of saline or prostaglandin was used rarely (0.1% of all abortions), primarily at <8 weeks or at >16 weeks' gestation.

From the National Pregnancy Mortality Surveillance System, CDC identified 26 deaths for 2003 that were thought to be potentially related to abortion. These deaths were identified either by some indication of abortion on the death certificate, from health-care providers, or from information such as a news or public health report associated with the death. Investigation of the 2003 cases revealed that 10 of the 26 deaths were related to legal induced abortion and none to illegal induced abortion (Table 19). Four of the 10 legal induced abortion-related deaths occurred following a medical (nonsurgical) abortion procedure. Ten deaths were related to spontaneous abortion, and four deaths were found not to be abortion related. The remaining three deaths were found to be not pregnancy related. Numbers of deaths related to legal induced abortion were highest before the 1980s, with few deaths occurring in 2003. Possible abortion-related deaths that occurred during 2004--2007 are being investigated.

Discussion

A total of 839,226 legal induced abortions were reported in the United States for 2004 from 47 states, DC, and NYC, reflecting a decline of 1.1% from the number of legal induced abortions reported for 2003. After five previous annual decreases, a slight increase of 0.1% in the number of abortions occurred in 2002, with another decline of 0.7% in 2003 and a further decline of 1.1% in 2004. This pattern also is apparent when the same 47 reporting areas that reported for all years, 1998--2004, are compared with those that reported for 2001--2004 (Table 2). Before 1998, a substantial number of legal induced abortions were estimated to have been performed in California (e.g., >23% of the U.S. total in 1997) (9). The lack of data for California for 2004 largely explains the majority of the 28% decrease from the annual number of abortions reported for 1997 (9) and part of the decrease in the total ratio and rate.

Overall, abortion ratios and rates have declined over time until 2002 (Figure 1). The abortion ratio for 2004 (238 per 1,000 live births for 49 reporting areas) decreased from the previous year (241). For the same reporting areas as 2000--2002, the abortion rate for women aged 15--44 years (16 per 1,000 women) remained identical to the rate reported since 2000, then was 15 per 1,000 women for 2003 and 16 for 2004 (Table 2). The overall declines in the abortion ratio and rate over time might reflect multiple factors, including a decrease in the number of unintended pregnancies (10); a shift in the age distribution of women toward the older and less fertile ages (11); reduced or limited access to abortion services, including the passage of abortion laws that affect adolescents (e.g., parental consent or notification laws and mandatory waiting periods) (12--16); and changes in contraceptive practices, including increased use of contraceptives (e.g., condoms and, among young women, long-acting hormonal contraceptive methods that were introduced in the early 1990s) (17--22).

In this report, the abortion rate for the United States was higher than rates reported for Canada and Western European countries and lower than rates reported for China, Cuba, the majority of Eastern European countries, and certain Newly Independent States of the former Soviet Union (23--25).

As in previous years, the abortion ratio in 2004 varied substantially by age. Although the abortion ratio was highest for adolescents in 2004, since the mid-1980s, the ratio had gradually declined for those aged <15 and 15--19 years, through 2000, but then increased through 2003, and again declined for 2004 (Figure 3). Other studies also have indicated a decrease in birth rates for females aged 10--14 and 15--19 years during 1991--2003 and a decrease in adolescent pregnancy rates during 1990--2000 (26--34). However, abortion rates have not varied equally among women of all races and ethnicities. Abortion rates are declining more slowly among adolescents who are not enrolled in school (10,34).

The percentage distribution of abortions by known weeks of gestation has shifted slightly since the late 1970s. From 1992 (when detailed data on early abortions were first available) through 2002, data have indicated steady increases in procedures performed at <6 weeks' gestation, with a minimal decrease in 2003 but another increase in 2004. Decreases occurred in the percentage of abortions performed at 8 and 9--10 weeks, and at 11--12 weeks' gestation through 2002, with a minimal increase at 11--12 weeks in 2003, but further decreases in all these groups for 2004. The increase in the percentage of abortions performed at <6 weeks' gestation might be related to an increase in the availability of early abortion services since 1992 and an increase in medical and surgical procedures that can be performed early in gestation (35,36). Abortions performed early in pregnancy are associated with lower risks for mortality and morbidity (37,38). The proportions of abortions performed later in pregnancy (>13 weeks) have varied minimally since 1992. The gestational age at which an abortion is obtained can be influenced by multiple factors in addition to those for which surveillance data are available (i.e., age, race, and ethnicity). These additional factors include level of education, availability and accessibility of abortion services, timing of confirmation of pregnancy, timing of personal decision-making, timing of prenatal diagnosis, level of fear of discovery of pregnancy, and denial of pregnancy (39--41).

Since the mid-1990s, two medical regimens (mifepristone and methotrexate, each used in conjunction with misoprostol) have been tested in clinical trials and used by clinical practitioners to perform early medical abortions (36,42). CDC surveillance data indicate that approximately 61% of all U.S. abortions are performed at <8 weeks' gestation, which is similar to the timing of the regimen used for both mifepristone and methotrexate (38,43). Mifepristone for medical abortion was approved in September 2000 by the U.S. Food and Drug Administration (FDA) for distribution and use in the United States. The FDA-approved protocol can be initiated at <49 days of gestation and requires three office visits by the patient: administration of oral mifepristone, followed 48 hours later by oral misoprostol in the health-care provider's office, and a follow-up visit in approximately 14 days. Clinical studies of alternative medical abortion regimens have been performed in multiple countries and are ongoing (44--52). Second trimester nonsurgical abortion with mifepristone and misoprostol or misoprostol alone also have been clinically effective (53,54).

In 1997, the U.S. ITOP standard report published by NCHS and used by providers for abortion reporting to state health departments was revised to include a category for "medical (nonsurgical)" procedures (55). Medical abortion procedures have been included in this report since then as a separate category. CDC will continue to monitor early medical procedures and to report on the number of these procedures (Table 8).

The percentage of abortions known to be performed by curettage increased from 88% in 1973 to >96% during 1980--2001 and then decreased to 89% in 2004 (Table 1), and the percentage of abortions performed by intrauterine instillation declined sharply, from 10% in 1973 to <1% since 1989. The increase in use of curettage at >13 weeks probably is attributable to the lower risk for complications associated with the procedure (56,57). The percentage of abortions performed by curettage at >13 weeks' gestation (D&E) increased from 31% in 1974 (the first year for which these data were available) to 97% in 2004, and the percentage of abortions performed by intrauterine instillation at >13 weeks' gestation decreased from 57% to 0.5%; the percentage of medical abortions increased from 1.0% in 2000 to 9.3% in 2004 (Table 18) (58,59).

The proportion differential of the abortion ratio for black women and that for white women increased from 2.0 in 1989 (the first year for which black and other races were reported separately) to 2.9 in 2004 (60). In addition, the abortion rate for black women has been approximately three times as high as that for white women (range: 2.6--3.1) since 1991 (the first year for which rates by race were published) (61). These rates by race are substantially lower than rates previously published by NCHS (33) and indicate that the reporting areas for the 2004 report might not be representative of the U.S. black female population of reproductive age. The lack of data from California in this report skews the rates. Abortion patterns among white and Hispanic women should be considered with the understanding that a substantial majority of Hispanic women report themselves as white (3,26). Therefore, data for certain white women represent white women of Hispanic ethnicity.

In 2004, a total of 38 states, DC, and NYC reported Hispanic ethnicity of women who obtained abortions. Because of concerns regarding the completeness of such data (>15% unknown data) in certain states, in 2004, data from only 25 states, DC, and NYC were used to determine the number and percentage of abortions obtained by women of Hispanic ethnicity. These geographic areas represent approximately 46% of reproductive-age Hispanic women in the United States for 2004 and approximately 50% of U.S. Hispanic births (3,26). Therefore, the number of Hispanic women who obtained abortions was underestimated, and the number, ratio and rate of abortions for Hispanic women in this report are not generalizable to the overall Hispanic population in the United States. In addition, the value of making comparisons between the Hispanic and non-Hispanic populations is difficult because of the diversity in nationality.

Abortion ratios for both Hispanic and non-Hispanic women have declined considerably since 1992 (31% and 27% respectively). As in the past, the abortion rate for Hispanic women was higher (26 per 1,000 women) than the rate for non-Hispanic women (13 per 1,000). Race- and ethnicity-specific differences in legal induced abortion ratios and rates might reflect differences among populations in socioeconomic status, access to and use of family planning and contraceptive services, contraceptive use, and incidence of unintended pregnancies.

NCHS vital statistics reports indicate that fertility and live birth rates were substantially higher for Hispanic women than for non-Hispanic women for all age groups in 2004 (26). However, because fertility and live birth rates differ substantially among both the different Hispanic (i.e., Mexican, Puerto Rican, Cuban, and other Hispanic) and non-Hispanic (white, black, and other) subpopulations, comparisons between Hispanic and non-Hispanic populations are of limited value (26). Available abortion surveillance data do not permit cross-classification of race by Hispanic ethnicity.

Compared with the early 1970s, the annual number of deaths associated with known legal induced abortion in the early 2000s has decreased by approximately two thirds (Table 19). In 1972, a total of 24 women died from causes known to be associated with legal abortions, and 39 died as a result of known illegal abortions. At most, two illegal abortion deaths have occurred in any year since 1979. In 2003, 10 women died from causes known to be associated with legal induced abortions, and none died as a result of known illegal induced abortion. National case-fatality rates for 1998--2003 cannot be calculated because a substantial number of abortions occur in nonreporting states (four states in 1998 and 1999 and three states in 2000--2003); therefore, the total number of abortions (the denominator) is unknown.

Of the 10 legal induced abortion-related deaths identified in 2003, four occurred following a medical (nonsurgical) abortion procedure. Two of these cases have been described previously (62). This is the first year for which maternal deaths related to medical abortion procedures have been identified.

Limitations

These data are reported voluntarily and are subject to at least five limitations. First, abortion data are compiled and reported to CDC by the central health department in the reporting area in which the abortion was performed rather than the area in which the woman resided. This choice of area inflates the numbers, ratios, and rates of abortions for areas in which a high proportion of legal abortions are obtained by out-of-state residents and undercounts procedures for states with limited abortion services or more stringent legal requirements for obtaining an abortion (causing women to seek abortions elsewhere). Second, four states (Alaska, California, New Hampshire, and Oklahoma) did not report abortion data for 1998--1999, three states (Alaska, California, and New Hampshire) did not report data for 2000--2002, and three states (California, New Hampshire, and West Virginia) did not report data for 2003--2004. Data for California and Oklahoma were estimated before 1998; however, data for nonreporting states have not been estimated since then. Third, data provided to state or area health departments by providers might be incomplete (63). Fourth, the overall number, ratio, and rate of abortions are conservative estimates; the total numbers of legal induced abortions provided by central health agencies and reported to CDC for 2004 were probably lower than the numbers actually performed. In addition, the abortion total for 2000 provided to CDC by central health agencies are 20% lower than that reported for 2000 (the most recent year for which data are available) for the same reporting areas by The Alan Guttmacher Institute, a private organization that contacts abortion providers directly (64). A previous report documented a discrepancy of approximately 12% (65); the reasons for this larger discrepancy are unclear. Finally, because not all states collected or reported data on all characteristics (e.g., age, race, and the number of weeks' gestation) of women obtaining a legal induced abortion in 2004, the numbers, rates, and ratios derived in this analysis might not be representative of all women who obtained abortions.

Public Health Actions

Despite these limitations, findings from ongoing national surveillance of legal induced abortion are useful for at least five purposes. First, public health agencies use data from abortion surveillance to identify characteristics of women who are at high risk for unintended pregnancy and use this information to develop interventions to prevent such pregnancies. Second, ongoing annual surveillance is used to monitor trends in the number, ratio, and rate of abortions in the United States. Third, statistics regarding the number of pregnancies ending in abortion are used in conjunction with birth data and fetal death computations to estimate pregnancy rates (e.g., pregnancy rates among adolescents) (27--31,33). Fourth, abortion and pregnancy rates can be used to evaluate the effectiveness of family planning programs and programs for preventing unintended pregnancy. Finally, ongoing surveillance provides data for assessing changes in clinical practice patterns related to abortion (e.g., longitudinal changes in the types of procedures and trends in weeks of gestation at the time of abortion).

The Health Insurance Portability and Accountability Act (HIPAA) was enacted by Congress in 1996 to facilitate the electronic transfer of health data relating primarily to insurance coverage and transferability (66). HIPAA provisions mandate adoption of federal privacy protections for certain individually identifiable health information. The U.S. Department of Health and Human Services issued the Privacy Rule that became effective on April 14, 2003. Because the Privacy Rule exempts protected health information required for public health purposes from privacy protections, covered entities might provide such information without a person's authorization to a public health authority (e.g., CDC) whose stated purpose is to prevent and control disease. Collection of surveillance data for this report is exempt from the Privacy Rule. However, the complexity of the rule might result in difficulties in its interpretation and, therefore, in collecting surveillance data on the part of certain contributing agencies (66).

Approximately one in five U.S. pregnancies have ended in abortion according to a national sample survey conducted by AGI during 2001--2002 among women having abortions (64). Inconsistent method use of the oral contraceptives (75.9%) or condoms (49.3%) was the most common reason that women became pregnant and obtained abortions (22). Unintended pregnancy is a pervasive public health problem for all population subgroups and women of reproductive age (10,61,67).

Although induced abortions usually are performed for women who have unintended pregnancies, which often occur despite the use of contraception, the approximately 4.6 million women who have had intercourse during the preceding 3 months but were not using contraception might be the most at risk for unintended pregnancy (18). Therefore, a reduction in the number of abortions will require adapting complex strategies aimed at reducing such pregnancies. Insurance coverage of reversible contraception (e.g., vasectomy and tubal ligation) has increased substantially since 1993 (68), although gaps in coverage remain substantial. Education regarding abstinence and contraceptive use, including emergency contraception, combined with access to and education regarding safe, effective contraception and family planning services, might help reduce the incidence of unintended pregnancy and the number of legal induced abortions in the United States (69,70).

Acknowledgments

The authors thank Kristi Seed, Division of Reproductive Health, National Center for Chronic Disease Prevention and Health Promotion, CDC, for her help with the tables.

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** After exclusion of 13 areas in which ethnicity data were unknown for >15% of women who obtained an abortion.

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