Confined placental mosaicism revisited: Impact on pregnancy characteristics and outcome

Objectives We wanted to re-evaluate the influence of confined placental mosaicismsubtypes (type 2 and type 3) on pregnancy characteristics and outcome. Material and methods From July 2009 to December 2015, 5512 chorionic villus samplingswere performed in our Fetal Medicine Center. Conventional karyotyping was performed after long-term and short-term cultured villi to define type 2 or type 3 confined placental mosaicisms. Karyotype after amniocentesiswas performed to exclude true fetal mosaicism, when appropriate. Pregnancy characteristics and outcomes were collected and compared to a control population. Results Thirty-six (0.65%) confined placental mosaicismswere observed (13 type 2 and 23 type 3). Nuchal translucency was not increased for type 2 and type 3 confined placental mosaicisms. Pregnancy characteristics and outcomes were comparable between type 2 confined placental mosaicismsand the control population. In type 3 confined placental mosaicisms, median first trimester serum pregnancy-associated plasma proteinA was lower than for the control population (p<0.001), preterm births were noticed in 56% (p<0.001), smallfor gestational agenewborns in 74% (p<0.001), and adverse pregnancy outcome was reported in 35% (p<0.01). Conclusion Although type 2 confined placental mosaicismsappeared to have no influence on pregnancy characteristics and outcome, type 3 confined placental mosaicismswere associated with low levels of first trimester serum pregnancy-associated plasma proteinA, preterm birth, smallfor gestational agenewborns, and adverse pregnancy outcomes.