Polyploidy arises from a complete extra set or sets of new chromosomes.
Triploidy commonly arises from fertilization with two sperm, or from failure of one or the maturation divisions of either the egg or the sperm, so producing a diploid gamete. 69, XXY is the most common triploid state.
Tetraploidy is usually due to failure to complete the first zygotic division.
Polyploid fetuses miscarry in the majority of cases.
Last reviewed 01/2018