Outcome of pregnancy after amniocentesis for chromosome analysis

A consecutive series of 1177 pregnant women examined by amniocentesis for chromosomal abnormalities delivered 1039 live-born babies weighing over 2500 g and 79 live-born babies weighing under 2500 g. Twenty-six abortions were induced (2.2%)--13 (1.1%) because of chromosomal abnormalities--and 28 women (2.4%) aborted spontaneously; in these cases chromosomes were normal. Analysis of all spontaneous abortions in the series suggested that 0.3-0.7% might have resulted from amniocentesis.