Cytogenetic analysis of 688 couples experiencing multiple spontaneous abortions.

We report on cytogenetic analysis of 688 couples experiencing two or more first- and/or second-trimester abortions (less than 20 weeks). The overall abnormality rate was 6.83% (47 couples). However, exclusion of those anomalies not generally accepted as being causal in spontaneous abortion leaves an abnormality rate of only 2.33% (16 couples). We discuss the significance of balanced translocations, inversions, sex chromosome aneuploidies, and mosaicisms thereof in the causation of multiple abortions.