Embryonic karyotype of abortuses in relation to the number of previous miscarriages.

OBJECTIVE: To examine the frequency of chromosomal abnormalities in products of conception from patients with recurrent miscarriages in relation to the number of previous miscarriages.

DESIGN: Retrospective analysis.

SETTING: Nagoya City University Medical Hospital.

PATIENT(S): A total of 1,309 women with a history of 2-20 consecutive first-trimester abortions.

INTERVENTION(S): Chromosomal analysis performed on products of conception with use of a standard G-banding technique.

MAIN OUTCOME MEASURE(S): The frequencies of abnormal and normal embryonic karyotypes for each number of previous abortions were studied. The subsequent pregnancy outcome of patients whose previous miscarriages were karyotyped were studied along with the predictive value of karyotyping of previous miscarriages for subsequent miscarriages.

RESULT(S): The miscarriage rate increased with the number of previous spontaneous abortions. The frequency of abnormal embryonic karyotypes significantly decreased and that of normal embryonic karyotypes significantly increased with the number of previous abortions. Among 71 patients whose embryonic karyotypes were normal, 44 aborted subsequently, and 23 of 60 patients whose embryonic karyotypes were abnormal aborted subsequently. Patients with a previous normal embryonic karyotype aborted more frequently than those with an abnormal karyotype.

CONCLUSION(S): The frequency of normal embryonic karyotypes significantly increases with the number of previous abortions, and a normal karyotype in a previous pregnancy is a predictor of subsequent miscarriage.