First trimester prenatal diagnosis: earlier is not necessarily better.

In the past few years considerable attention has been given to a relatively new method of prenatal diagnosis known as chorionic villus sampling (CVS). Because CVS can be performed in the first trimester it is hailed by many as a significant advance over amniocentesis. What has not been as publicized, however, are the disadvantages of CVS and earlier prenatal diagnosis. The emotional costs of CVS in terms of the greater number of both spontaneous and selective abortions following CVS, the use of CVS for sex selection and, because of the greater social acceptability of first trimester abortion, the possibility of increased pressure on women to undergo prenatal diagnosis by health insurance companies, medical professionals and government agencies, all need to be weighed against the advantages of early prenatal diagnosis.