Fergusson D M, Horwood L J, Wright R, Stewart C R
N Z Med J. 1978 Aug 9;88(617):89-92.
The incidence of unplanned pregnancy in a cohort of 1038 mothers of nuptial children was examined. The major findings were: (1) about one third of the pregnancies were unplanned but there was little evidence that unplanned children were unwanted; (2) there was no evidence to suggest that unplanned birth was related to poor education, low socio-economic status or lack of knowledge of contraception; (3) 40 percent of unplanned births were the result of contraceptive failure; (4) a common denominator in 38 percent of unplanned births was failure or breakdown in the woman's usage of the contraceptive pill.
对1038名婚生子女的母亲组成的队列中的意外怀孕发生率进行了调查。主要发现如下：（1）约三分之一的怀孕是意外怀孕，但几乎没有证据表明意外生育的孩子是不受欢迎的；（2）没有证据表明意外生育与教育程度低、社会经济地位低或缺乏避孕知识有关；（3）40%的意外生育是避孕失败的结果；（4）38%的意外生育的一个共同因素是女性使用避孕药失败或出现问题。
