Abstract
Aneuploidy is a very common occurrence in humans and occurs in an estimated 20–40% of all pregnancies. It is the most prominent cause of miscarriages and congenital defects in humans and is the main obstacle to infertility treatment. The vast majority of aneuploidies are caused by maternal meiotic non-disjunction errors. High levels of recombination errors were observed in studies on fetal oocytes. This suggests that some oocytes are more prone to not being separated due to events occurring before birth. Cell cycle checkpoints that work in the meiotic phase and metaphase-anaphase transition work more moderately in women than in men. As a result, while there are abnormal cells that have been sorted out in spermatogenesis, in females these cells can escape the actual control and ultimately give rise to aneuploid eggs.