Moreau C, Trussell J, Rodriguez G, Bajos N, Bouyer J
Office of Population Research, Princeton University, Wallace Hall, Princeton, NJ 08544, USA.
Hum Reprod. 2007 Sep;22(9):2422-7. doi: 10.1093/humrep/dem184. Epub 2007 Jun 28.
Despite the widespread use of highly effective contraceptive methods in France, one in every three pregnancies is unintended, of which 65% occur while using contraceptives. In the USA, 49% of pregnancies are unintended, half of which result from contraceptive failure. This study provides estimates of method-specific failure rates among French women.
We use data from the 2000 Cocon Study, a population-based cohort, comprising a representative sample of 1689 women aged 18-44 years who described their contraceptive history. Piecewise-constant hazards models were used to estimate method-specific contraceptive failure rates during the first 5 years of contraceptive use. A random effect was introduced to take into account the fact that some women contribute more than 1 contraceptive episode. These same models were used to assess the effects of socio-demographic characteristics on the probability of contraceptive failure among pill, intrauterine device (IUD) and condom users.
Overall, 2.9% of women experienced a contraceptive failure in the first year of use and 8.4% in the first 5 years of use. The IUD had the lowest first year failure rate (1.1%), followed by the pill (2.4%), the condom (3.6%), fertility awareness methods (periodic abstinence or safe period by temperature) (7.7%), withdrawal (10.1%) and spermicides (21.7%). These failure rates varied little by user characteristics.
Lower failure rates among French women compared with those reported for US women suggest differences in contraceptive practices which need to be further explored.
尽管高效避孕方法在法国广泛使用，但每三例怀孕中就有一例是意外怀孕，其中65%发生在使用避孕措施期间。在美国，49%的怀孕是意外怀孕，其中一半是避孕失败导致的。本研究提供了法国女性特定避孕方法失败率的估计值。
我们使用了2000年椰子研究的数据，这是一项基于人群的队列研究，包括1689名年龄在18 - 44岁之间描述其避孕史的具有代表性的女性样本。采用分段常数风险模型来估计避孕使用前5年特定方法的避孕失败率。引入随机效应以考虑一些女性经历不止一次避孕过程这一事实。这些相同的模型用于评估社会人口学特征对口服避孕药、宫内节育器（IUD）和避孕套使用者避孕失败概率的影响。
总体而言，2.9%的女性在使用的第一年经历了避孕失败，在使用的前5年中这一比例为8.4%。宫内节育器第一年的失败率最低（1.1%），其次是口服避孕药（2.4%）、避孕套（3.6%）、生育意识方法（周期性禁欲或体温安全期）（7.7%）、体外射精（10.1%）和杀精剂（21.7%）。这些失败率因使用者特征的不同而变化不大。
与美国女性报告的失败率相比，法国女性较低的失败率表明避孕做法存在差异，需要进一步探讨。
