Genetic counselling and prenatal diagnosis for chromosome anomalies. Use of study of spontaneous abortions.

Genetic counselling for chromosome abnormalities must take into account the fact that such anomalies may develop as an error in oogenesis or spermatogenesis or may be transmitted from parents. Since many chromosomally abnormal embryos are spontaneously aborted, parents with repeated unfavorable outcomes of pregnancy or difficulty in conceiving should be studied by karyotype. The relationship between chromosomal abnormalities and various environmental or biologic factors are discussed. The outcome of a previous pregnancy may indicate the necessity of subsequent fetal evaluation even with chromosomally normal parents.