Pregnancy termination because of chromosomal abnormalities: a study of 26,950 amniocenteses in the southeast.

A regional study was done to investigate the outcome of chromosomally abnormal pregnancies with respect to the parental decision to continue or to terminate the pregnancy. Fourteen medical centers in the southeastern United States contributed data on 26,950 amniocenteses. In 416 cases (1.54%), cytogenetic abnormalities were reported. Of 378 singleton pregnancies in which a cytogenetic abnormality was reported and for which information regarding pregnancy outcome was available, the decision to terminate the pregnancy was made in 276 (73.02%). When the chromosomal abnormality was autosomal in nature, 240 of the 293 pregnancies (81.91%) were terminated, as compared to 36 of the 85 pregnancies (42.35%) affected with a sex chromosomal abnormality. Pregnancies involving the most common autosomal trisomies (21, 18, and 13) were terminated at a rate of 92% to 95%. No significant difference in the rate of abnormality or in the rate of pregnancy termination existed between the 14 centers. Our findings reflect the largest series of amniocentesis results collected to date.