Department of Population Health, London School of Hygiene & Tropical Medicine, London, UK.
Department of Public Health, Environments and Society, London School of Hygiene & Tropical Medicine, London, UK.
J Adolesc Health. 2020 May;66(5):582-588. doi: 10.1016/j.jadohealth.2019.11.310. Epub 2020 Feb 3.
Pregnancy rates among adolescents have declined in the U.S. and Britain but remain high compared with other high-income countries. This comparison describes trends in pregnancy rates, recent sexual activity, and contraceptive use among women aged 16-19 years in the U.S. and Britain to consider the contribution of these two behavioral factors to the decline in pregnancy rates in the two countries and the differences between them.
We use data from two rounds of the U.S. National Survey of Family Growth, conducted 2002-2003 and 2011-2015, and the British National Survey of Sexual Attitudes and Lifestyles, conducted 2000-2001 and 2010-2012, to describe population-level differences between countries and over time in sexual activity and contraceptive use. We calculate pregnancy rates using national births and abortions data.
Pregnancy rates declined in both countries; this began earlier in the U.S. and was steeper. There was no change in sexual activity in Britain, but in the U.S., the proportion reporting recent sex declined. In both countries, there was a shift toward more effective contraception. A higher proportion in Britain than the U.S. reported ever having had sex (65% vs. 49%) and sex in the last year (64% vs. 45%), 6 months (59% vs. 39%), and 4 weeks (48% vs. 29%). A higher proportion in Britain reported using more effective contraception (68% vs. 52%).
In both countries, improvements in contraceptive use have contributed substantially to declines in pregnancy rates; however, the steeper decline in the U.S. likely also reflects declines in recent sex occurring only in that country.
美国和英国青少年的怀孕率有所下降，但与其他高收入国家相比仍处于较高水平。本研究比较了美国和英国 16-19 岁女性的怀孕率、近期性行为和避孕措施使用情况，以探讨这两个行为因素对两国怀孕率下降的贡献，以及两国之间的差异。
我们使用了美国国家家庭增长调查（2002-2003 年和 2011-2015 年）和英国全国性态度和生活方式调查（2000-2001 年和 2010-2012 年）的两轮数据，描述了两国之间以及随着时间的推移在性行为和避孕措施使用方面的人群差异。我们使用国家出生和堕胎数据计算怀孕率。
两国的怀孕率都有所下降；美国开始得更早，下降得更陡峭。英国的性行为没有变化，但在美国，报告近期有性行为的比例有所下降。在两国，更有效的避孕措施的使用比例都有所上升。与美国相比，英国报告曾有过性行为（65%比 49%）和过去一年有过性行为（64%比 45%）、过去 6 个月有过性行为（59%比 39%）和过去 4 周有过性行为（48%比 29%）的比例更高。英国报告使用更有效的避孕措施的比例也更高（68%比 52%）。
在这两个国家，避孕措施的改进对怀孕率的下降做出了重大贡献；然而，美国怀孕率下降幅度更大，可能也反映了只有该国近期性行为出现下降。
