Henshaw S K
Alan Guttmacher Institute, New York, USA.
Fam Plann Perspect. 1998 Jan-Feb;30(1):24-9, 46.
Current debates on how to reduce the high U.S. abortion rate often fail to take into account the role of unintended pregnancy, an important determinant of abortion.
Data from the 1982, 1988 and 1995 cycles of the National Survey of Family Growth, supplemented by data from other sources, are used to estimate 1994 rates and percentages of unintended birth and pregnancy and the proportion of women who have experienced an unintended birth, an abortion or both. In addition, estimates are made of the proportion of women who will have had an abortion by age 45.
Excluding miscarriages, 49% of the pregnancies concluding in 1994 were unintended; 54% of these ended in abortion. Forty-eight percent of women aged 15-44 in 1994 had had at least one unplanned pregnancy sometime in their lives; 28% had had one or more unplanned births, 30% had had one or more abortions and 11% had had both. At 1994 rates, women can expect to have 1.42 unintended pregnancies by the time they are 45, and at 1992 rates, 43% of women will have had an abortion. Between 1987 and 1994, the unintended pregnancy rate declined by 16%, from 54 to 45 per 1,000 women of reproductive age. The proportion of unplanned pregnancies that ended in abortion increased among women aged 20 and older, but decreased among teenagers, who are now more likely than older women to continue their unplanned pregnancies. The unintended pregnancy rate was highest among women who were aged 18-24, unmarried, low-income, black or Hispanic.
Rates of unintended pregnancy have declined, probably as a result of higher contraceptive prevalence and use of more effective methods. Efforts to achieve further decreases should focus on reducing risky behavior, promoting the use of effective contraceptive methods and improving the effectiveness with which all methods are used.
当前关于如何降低美国高堕胎率的辩论往往未能考虑意外怀孕的作用，而意外怀孕是堕胎的一个重要决定因素。
利用1982年、1988年和1995年全国生育调查周期的数据，并辅以其他来源的数据，来估计1994年意外生育和怀孕的发生率、百分比，以及经历过意外生育、堕胎或两者皆有的女性比例。此外，还对到45岁时会堕胎的女性比例进行了估计。
排除流产情况，1994年结束的妊娠中有49%是意外妊娠；其中54%以堕胎告终。1994年，年龄在15 - 44岁的女性中有48%在其一生中曾有过至少一次意外怀孕；28%有过一次或多次意外生育，30%有过一次或多次堕胎，11%两者皆有。按照1994年的发生率，女性到45岁时预计会有1.42次意外怀孕，按照1992年的发生率，43%的女性会有过堕胎经历。1987年至1994年期间，意外怀孕率下降了16%，从每1000名育龄妇女中的54例降至45例。在20岁及以上的女性中，意外怀孕后堕胎的比例有所上升，但在青少年中有所下降，现在青少年比年长女性更有可能继续她们的意外妊娠。意外怀孕率在年龄为18 - 24岁、未婚、低收入、黑人或西班牙裔的女性中最高。
意外怀孕率有所下降，可能是由于避孕普及率提高以及使用了更有效的方法。要进一步降低意外怀孕率，应致力于减少危险行为，推广使用有效的避孕方法，并提高所有避孕方法的使用效果。
