Epigenetic changes and assisted reproductive technologies

Abstract

Children conceived by Assisted Reproductive Technologies (ART) are at moderately increased risk for a number of undesirable outcomes, including low birth weight. Whether the additional risk is associated with specific procedures used in ART or biological factors that are intrinsic to infertility has been the subject of much debate, as has the mechanism by which ART or infertility might influence this risk. The potential effect of ART clinical and laboratory procedures on the gamete and embryo epigenomes heads the list of mechanistic candidates that might explain the association between ART and undesirable clinical outcomes. The reason for this focus is that the developmental time points at which ART clinical and laboratory procedures are implemented are precisely the time points at which large-scale reorganization of the epigenome takes place during normal development. In this manuscript, we review the many human studies comparing the epigenomes of ART children with children conceived in vivo, as well as assess the potential of individual ART clinical and laboratory procedures to alter the epigenome.

Keywords: ART; IVF; epigenome; methylation; programming.

Figure 1.

In vitro fertilization involved multiple exposures and manipulations to the gamete and embryo including superovulation, the surgical retrieval of oocytes, in vitro fertilization by sperm or injection of a single sperm into the oocyte (Intracytoplasmic sperm injection), the culture of fertilized embryos for 3–5 days, and the transfer of fresh embryos and/or embryo cryopreservation.