Are clinical and biological IVF parameters correlated with chromosomal disorders in early Life: a multicentric study

A multicentric study was carried out to analyse in a large series:(i) the chromosomal status of unfertilized oocytes, (ii) errorsat fertilization and (iii) the chromosomal complement of cleavedembryos. Parameters such as type of sterility, maternal age,stimulation treatment, doses of gonadotrophins administeredand oocyte preincubation time before insemination were studiedin relation to the incidence of chromosome abnormalities. Twenty-sixper cent of the unfertilized oocytes and 29.2% of the embryoshad chromosome anomalies. Maternal age significantly increasedthe rate of aneuploidy in oocytes: 38% in patients over 35 years(versus 24% in younger patients). Fertilization-related abnormalitieswere significant, i.e. 1.6% parthenogenesis and 6.4% polyploidy.Unexplained infertility was correlated with an increase in therate of parthenogenesis (4.2%) when compared with tubal infertility(1.2%). Triploidy was found to be correlated with three parameters.A lower rate of triploidy was observed in the group of couplesreferred because of male sterility (1.9% versus 6.3% for tuba1sterility), in HMG-treated patients (2.4% versus 7% with analoguesof LHRH/HMG) and with a short 2-h preincubation time beforeinsemination (3% versus 7.2% for > 2 h). A general modelfor natural selection against embryos carrying a chromosomeimbalance was proposed.