INCREASED INCIDENCE OF CYTOGENETIC ABNORMALITIES IN CHORIONIC VILLUS SAMPLES FROM PREGNANCIES ESTABLISHED BY IN-VITRO FERTILIZATION AND EMBRYO-TRANSFER (IVF-ET)

We studied 201 pregnancies that were established by in vitro fertiliza tion and embryo transfer (IVF-ET) and compared the frequency of cytoge netic abnormalities with that found in a large control population matc hed for indication group (advanced maternal age) and time of sampling. A total of 252 IVF-ET fetuses were cytogenetically analysed by either chorionic villus sampling (CVS; n=80) or amniocentesis (n=172). Eleve n chromosome abnormalities were found in the CVS group (13 . 8 per cen t); among them, a 45,X/46,X,dic(Y)(q11)/46,X,del(Y)(q11) mosaic that w as found in an IVF pregnancy established by intracytoplasmic sperm inj ection (ICSI), four cases of trisomy 21, and three cases of trisomy 7 confined to the placenta. The results indicate a statistically signifi cant three-to five-fold increase in both confined placental abnormalit ies (P<0 . 008) and true fetal chromosome anomalies (P<0 . 04). In the amniocentesis group, identical rates (1 . 7 per cent) of chromosome a bnormalities were found in the IVF-ET and control groups. It is conclu ded that late first trimester, but not early second trimester, IVF-ET pregnancies are characterized by an increased frequency of cytogenetic abnormalities found at prenatal diagnosis.