A cytogenetic study of human spontaneous abortions using banding techniques.

The karyotypes of 941 singleton and 42 twin abortuses and 4 cystic placentae were determined. 30.5% of the singletons were chromosomally abnormal; 49.8% of these were trisomic, 23.7% X-monosomics and 17.4% polyploid. 143 trisomies were identified by banding; over a third had an extra chromosome 16, more than 10% an extra 21 or 22 and about 5% an extra 2, 18 or 15. Examples of trisomy 3, 4, 8, 9, 10, 13, 14 and 20 were also encountered. Using the data from two other published studies, the prevalence of different trisomies was estimated and an attempt was made to relate the karyotype of the conceptus to its subsequent development.