1. In 1998 and 1999 Alaska, California, New Hampshire, and Oklahoma did not report abortion data to CDC. For comparison, in 1997 the 48 corresponding reporting areas reported about 900,000 legal abortions.

2. In 2000, 2001, and 2002 Alaska, California, and New Hampshire did not report abortion data to CDC.

3. No surveys were conducted in 1983, 1986, 1989, 1990, 1993, 1994, 1997, 1998, 2001, or 2002. Data for these years were estimated by interpolation.

4. For calculation of ratios by each characteristic, abortions with characteristic unknown were distributed in proportion to abortions with characteristic known.

5. For 1989 and later years, white race includes women of Hispanic ethnicity.

6. Before 1989 black race includes races other than white.

7. Reporting area increased from 20–22 States, the District of Columbia (DC), and New York City (NYC) in 1991–95 to 31 States and NYC in 2002. California, Florida, Illinois, and Arizona, states with large Hispanic populations, do not report Hispanic ethnicity.

8. For calculation of percent distribution by each characteristic, abortions with characteristic unknown were excluded.

9. For 1975, data refer to four previous live births, not four or more. For five or more previous live births, the ratio is 47.3.

10. For calculation of percent distribution by each characteristic, abortions with characteristic unknown were excluded.