A PROSPECTIVE CYTOGENETIC STUDY IN 3RD-TRIMESTER PLACENTAS OF FETUSESWITH UNEXPLAINED INTRAUTERINE GROWTH RESTRICTION

Objective: The purpose of this study was to see if chromosomal mosaici sm confined to the placenta was more frequently found in pregnancies c omplicated by intrauterine growth restriction. Methods: Placentas from 20 pregnancies resulting in appropriately grown term infants and 20 p regnancies complicated by unexplained fetal growth restriction were pr ospectively identified. Placental tissue culture and cytogenetic analy sis were performed to evaluate chromosomal mosaicism confined to the p lacenta. Results: One of the placentas from the group of growth-restri cted infants demonstrated a high level of mosaicism for tetraploidy (4 6,XX/92,XXXX). Normal placental karyotypes were found in the control g roup. Conclusion: It is suggested that mosaic abnormalities confined t o the placenta, unrelated to culture artifact or fetal karyotype, may occur more frequently than is currently recognized. Further studies ma y reveal whether tetraploidy is a nonrandom abnormality.