MKI67 and pregnancy disorder: Similarly, in the RV myocardium of children with congenital malformations, the highest number of Ki67-positive CMCs is at the age of one month (15.0 ± 0.1% of cells), at the age from one month to two years their number decreases to 8.0 ± 0.3% of cells, and over age two—decreases to 5.0 ± 0.2% of cells [45].