One thousand consecutive midtrimester amniocenteses.

One thousand women underwent amniocentesis as part of a prenatal investigation and were observed throughout gestation and delivery. Amniocenteses and chromosome determinations were performed at a center with great experience in these techniques. Under these conditions, the risks attached to amniocentesis are minimal, and the chromosome determinations are reliable. In this study, 21 women chose to terminate their pregnancy because the fetus was expected to have a serious abnormality. In all the cases in which the diagnosis could be investigated after legal termination, the cytogenetic diagnosis proved correct.