A reanalysis of the repeat abortion experience of New York City residents during July 1, 1970 to June 30, 1972 is undertaken on the basis of a probability model that generates repeat abortion ratios as a function of assumptions about fecundity, contraceptive efficiency, and exposure lengths. Tested are three hypotheses put forward by Daily et al. in a 1973 analysis: (i) the low repeat abortion ratio of .0245 is attributable in part to underreporting of registered induced abortions as repeat ones; (ii) a major part of the rise in repeat abortion ratios, from virtually zero to six percent over four consecutive six-month intervals, is explainable in terms of the rising volume of exposure time to risk of repeat abortion relative to the stream of initial abortions; and (iii) the higher abortion ratios of women in their twenties compared to those of older or younger women is ascribable to "differences in fecundity and intercourse frequency." Support is found for the first two hypotheses, and a mixed outcome for the third.
基于一个概率模型，对1970年7月1日至1972年6月30日期间纽约市居民的重复堕胎经历进行了重新分析，该模型根据生育能力、避孕效率和暴露时长等假设生成重复堕胎率。对戴利等人在1973年分析中提出的三个假设进行了检验：（i）低重复堕胎率0.0245部分归因于将登记的人工流产漏报为重复堕胎；（ii）重复堕胎率在连续四个六个月间隔内从几乎为零上升到6%，这一上升的主要部分可以用相对于初次堕胎流而言，重复堕胎风险暴露时间的增加来解释；（iii）二十多岁女性的堕胎率高于年龄较大或较小的女性，这归因于“生育能力和性交频率的差异”。前两个假设得到了支持，第三个假设的结果好坏参半。
