Antenatal diagnosis in practice.

Over a period of 5 years, 434 women at risk of having abnormal babies have had antenatal daignostic tests carried out during the first half of their pregnancy by the laboratories of the Department of Human Genetics, University of Cape Town. From these investigations, it was predicted that 13 fetuses had chromosomal abnormalities, 6 had severe central nervous system defects and 4 had autosomal recessive metabolic disorders. In addition, 4 cases with X-linked recessive traits were monitored and 3 male fetuses were recognized. Affected pregnancies were terminated except for 1 with a fetal sex-linked disorder where the parents revoked their original decision. The diagnosis was confirmed by fetal autopsies in all cases except 4 (2 spontaneous abortions and 2 out-of-town terminations). There was only 1 case where culture failed and the pregnancy went to term with the birth of a baby with Down syndrome. Antenatal diagnosis is now an important part of normal clinical practice. The fact that the fetal abnormalities were recognized in 6% of pregnancies is justification for the use of this procedure.