FOLLOW-UP OF PREGNANCIES COMPLICATED BY PLACENTAL MOSAICISM DIAGNOSEDBY CHORIONIC VILLUS SAMPLING

Thirty-nine (2.3 per cent) of 1724 chromosome studies from diagnostic chorionic villus samplings (CVS) done between 1983 and 1990 showed eit her level III (true) mosaicism (1.2 per cent) or level II (pseudo-) mo saicism (1.1 per cent) for chromosomal aneuploidy. Follow-up informati on on these 39 pregnancies was collected from questionnaires to famili es, paediatricians, and obstetricians. For all cases in which the preg nancy was continued and further testing was accomplished, the mosaicis m was felt to be confined to the placenta. As compared with a control group of pregnancies evaluated by CVS with normal karyotypes, there wa s no increased incidence of pregnancy loss, congenital malformations, or developmental delay in the infants. Although intrauterine growth re tardation occurred in several of the level III mosaic cases, adequate catch-up growth has been demonstrated.