Role of the sperm, oocyte, and embryo in recurrent pregnancy loss

Disorders affecting the sperm, oocyte, or embryo may cause a significant fraction of spontaneous miscarriages and cases of recurrent pregnancy loss (RPL). Altered chromosomal integrity of sperm and oocytes, which is highly dependent of the age of the mother, represents a major cause of miscarriage and in turn RPL. Avoiding transfers of abnormal embryos is possible with preimplantation genetic testing for aneuploidies. Chromosomal anomalies may also be caused by structural rearrangements of one or several chromosomes in either parents, a finding encountered in 12% of couples with RPL, including in those who have had one or several healthy babies. More than 40% of these chromosomal rearrangements are identifiable on regular karyotypes. When abnormal findings are made, preimplantation genetic testing for monogenic disorders allows selection of disease-free embryos. Finally, asymmetric inactivation of the X chromosome has been found more commonly in women with RPL, but no specific treatment is currently available. ((C) 2020 by American Society for Reproductive Medicine.)

Automated summary

Disorders affecting sperm, oocytes, or embryos can lead to spontaneous miscarriages and recurrent pregnancy loss. Genetic testing can help avoid the transfer of abnormal embryos and select disease-free embryos. Additionally, chromosomal rearrangements may cause chromosomal anomalies, leading to miscarriage.