Guttmacher Institute has released a Fact Sheet on unintended pregnancies in the United States. Here's what I learned:

Most American families want two children. About half (49%) of the 6.7 million pregnancies in the United States each year (3.2 million) are unintended. By age 45, more than half of all American women will have experienced an unintended pregnancy, and three in 10 will have had an abortion. Unintended pregnancy rates are highest among poor and low-income women, women aged 18–24, cohabiting women and minority women. In 2006, black women had the highest unintended pregnancy rate of any racial or ethnic groups. In 2006, 43% of unintended pregnancies ended in abortion and 48% ended in birth. Compared with higher-income women, poor and low-income women are less likely to end an unintended pregnancy by abortion. In 2006, two-thirds (64%) of the 1.6 million births resulting from unintended pregnancies were paid for by public insurance programs, primarily Medicaid. Total public expenditures for births resulting from unintended pregnancies nationwide were estimated to be $11.1 billion in 2006. Two-thirds of U.S. women at risk for unintended pregnancy use contraception consistently and correctly throughout the course of any given year; these women account for only 5% of all unintended pregnancies. In contrast, the 19% of women at risk who use contraception inconsistently or incorrectly account for 43% of all unintended pregnancies. The 16% of women at risk who do not practice contraception at all for a month or more during the year account for 52% of all unintended pregnancies. Without publicly funded family planning services, the number of unintended pregnancies and abortions occurring in the United States would be nearly two-thirds higher among women overall and among teens; the number of unintended pregnancies among poor women would nearly double.