Intracytoplasmic sperm injection (ICSI) with spermatozoa from ejaculated sperm or, later on with epidydimal or testicular spermatozoa, has been used in reproductive medicine since 1991. In 1995, In’t Veld et al. reported a high incidence of sex-chromosomal aberrations in a small number of prenatal diagnostic tests, performed for maternal age. Our own results at that time as well as those from others were less striking, but there were grounds for concern (Liebaerset al., 1995). At this point (ie up to August 1997), a total of 1082 prenatal tests had been performed in pregnancies after ICSI carried out in the Centre for Reproductive Medicine of the Brussels Free University Hospital: 690 amniocenteses, 15 of which were abnormal; 392 chorionic villus samplings (CVS), 13 of which were abnormal; and seven cord blood punctures, which were control samples for previous amniocenteses and were normal. Mean maternal ages were 32.7 years (4.06) for patients undergoing amniocentesis and 32.1 years (4.11) for patients undergoing CVS. In these 1082 tests we observed 18 (1.66%), de-novo chromosomal aberrations: nine of these (0.83%) were sex-chromosomal aberrations and another nine (0.83%) were autosomal aberrations (trisomies and structural)(Table I).

The figures in Table I show that there is a statistically significant increase in sex-chromosomal aberrations (0.83%), since the 95% confidence limit of this percentage (0.3–1.6%) does not contain the aberration percentage (0.19–0.23%) described in the literature with regard to a neonatal population (Nielsen and Wohlert, 1991; Jacobs et al., 1992). The incidence of autosomal aberrations is due partly to the increase in trisomies, linked with higher maternal ages. On the other hand, there is also an increase in structural de-novo aberrations (0.36% compared with 0.07% in the literature) which is significant (Jacobs et al., 1992). The increase in inherited structural aberrations (one of them being non-balanced) is, of course, higher than in the general population but was predictable for the individual couples, where the father was carrying the structural anomaly in all but one case. An increased percentage of de-novo chromosomal aberrations may result from the ICSI procedure itself or it may be linked to a defined subgroup of males with impaired semen samples. It is interesting to observe that all de-novo sex-chromosomal aberrations were found after spermatozoa had been used from men with extreme oligoasthenoteratospermia (concentration 0.1–4.6106/ml; normal morphology 0–40%; progressive motility 0–18%)(World Health Organization, 1992; Devroey, 1997). So far, however, we have not observed any correlation between the occurrence of chromosomal anomalies and standard semen parameters in the male partner (concentration, motility, morphology).