Confined placental mosaicism and pregnancy outcome: a distinction needs to be made between types 2 and 3

Prenat Diagn. 2010 Dec;30(12-13):1155-64. doi: 10.1002/pd.2631.


Objective: To study the influence of types 2 and 3 confined placental mosaicism (CPM) on pregnancy outcome.

Method: From 13 809 chorionic villus samplings (CVSs), karyotype after long-term cultured villi (LTC-villi) was systematically performed. Next, in case of suspicion of CPM, karyotype after short-term cultured villi (STC-villi) was established to define type 2 CPM (chromosomal abnormality limited to the mesenchymal core) or type 3 CPM (chromosomal abnormality found both in the cytotrophoblast and the mesenchymal core). Confirmatory amniocentesis was performed to exclude fetal mosaicism. Uniparental disomy (UPD) testing was carried out when the abnormal cell line involved chromosomes 5, 6, 7, 15 or 16.

Results: Fifty-seven CPM cases were observed (57/13 809 = 0.41%) and of these, 37 were type 2 and 20 were type 3 CPM. Incidence of preterm infants, neonatal hypotrophy and adverse pregnancy outcome were comparable between patients in whom type 2 CPM was demonstrated and the control population. In contrast, for the type 3 CPM the incidence of these factors was higher than for the control population.

Conclusion: When a CPM is suspected, it appears essential to determine type, since type 2 has no effect on fetal development and type 3 is associated with preterm infants, low birth weight and adverse pregnancy outcome.

MeSH terms

  • Abortion, Eugenic / statistics & numerical data
  • Adult
  • Aneuploidy
  • Chorionic Villi Sampling / statistics & numerical data
  • Chromosome Aberrations / statistics & numerical data
  • Down Syndrome / epidemiology
  • Down Syndrome / genetics
  • Female
  • Humans
  • Infant, Newborn
  • Infant, Newborn, Diseases / epidemiology
  • Infant, Newborn, Diseases / genetics
  • Mosaicism / classification*
  • Mosaicism / statistics & numerical data
  • Placenta / metabolism*
  • Pregnancy
  • Pregnancy Outcome / epidemiology
  • Pregnancy Outcome / genetics*
  • Retrospective Studies