Discovery could improve in vitro fertilization success rates for women around the world

07/10/15  Portland, Ore.

Scientists identify ‘chromosomal fate’ of embryos at earliest stage of human development

Scientists at Oregon Health & Science University, Stanford University, University of Valencia and IGENOMIX have discovered that chromosomal abnormalities in human embryos created for in vitro fertilization, or IVF, can be predicted within the first 30 hours of development at the cell-1 stage which results from the union of a female egg and male sperm.

This discovery, published online today in the journal Nature Communications, could improve IVF success rates, which has hovered around 30 to 35 percent for numerous years worldwide. It is estimated that between 50 to 80 percent of embryos created for IVF have a chromosomal abnormality and typically do not develop into a pregnancy, instead resulting in a miscarriage.

Shawn Chavez

Shawn L. Chavez, Ph.D.

Key findings of this research, which was conducted by Shawn L. Chavez, Ph.D. and colleagues at Stanford University and analyzed at OHSU, showed that by looking at the duration of the first mitotic phase – a short period in the cell cycle – one can identify chromosomally normal versus abnormal embryos up to approximately the 8-cell stage. Most importantly, by looking at a single cell level, researchers were able to correlate the chromosomal make-up of an embryo to a subset of 12 genes that are activated prior to the first cell division. These genes likely came from the gametes – the eggs or sperm – and can be used to predict whether an embryo is chromosomally normal or abnormal at the earliest stage of human development.

As a result of these findings, clinicians and embryologists can more quickly identify the healthiest embryo for implantation and reduce the amount of time an embryo is cultured in the laboratory prior to transfer. Embryos typically need to be implanted within three to five days of creation, which has created a challenge for the IVF field because chromosomal abnormalities may not be identified until day five or six.

“Many couples are choosing to have children later in life, and this trend is only going to continue,” said Chavez, a co-author and assistant scientist in the Division of Reproductive and Developmental Sciences at the Oregon National Primate Research Center at OHSU; and assistant professor of Obstetrics and Gynecology, and Physiology and Pharmacology, in the OHSU School of Medicine. “A failed IVF attempt takes an emotional toll on a woman who is anticipating a pregnancy as well as a financial toll on families, with a single IVF treatment costing thousands and thousands of dollars per cycle. Our findings also bring hope to couples who are struggling to start a family and wish to avoid the selection and transfer of embryos with unknown or poor potential for implantation,” explained Chavez.

Read the full OHSU media release.