Egg Choice and In Vitro
Here’s some good news for women considering becoming pregnant using in vitro fertilization (IVF). A remarkable new discovery* could increase the chances of having a successful pregnancy—and a healthy baby. Scientists at Yale School of Medicine and the University of Oxford recently identified the chromosomal make-up of a human egg. It’s likely that this discovery will allow doctors to avoid choosing abnormal eggs during infertility treatments, and instead to use only those eggs that are healthy enough for a successful in vitro fertilization cycle.
Only a few of a woman’s eggs, or oocytes, in each IVF treatment cycle will result in a successful pregnancy because many eggs have the wrong number of chromosomes, a condition known as aneuploidy. The likelihood of producing aneuploid eggs increases as a woman ages.
Oocytes are surrounded by cells, called cumulus cells, which regulate the maturation of the egg. After studying the genes expressed in the cumulus cells, the Yale and Oxford scientists successfully identified a set of genes that are less active in cells that are associated with abnormal eggs. They also found that the expression of two genes was consistently underrepresented in cumulus cell surrounding abnormal eggs.
It sounds complicated, and it is, but the bottom line is that the finding will undoubtedly improve IVF success rates in the long run. The identification of the genes in the cumulus cells can serve as a non-invasive marker to identify abnormal eggs. Doctors can then choose the “right” egg with the potential to produce a successful pregnancy and even better, a healthy baby.
*E. Fragouli, D. Wells, A. E. Iager, U. A. Kayisli, P. Patrizio. Alteration of gene expression in human cumulus cells as a potential indicator of oocyte aneuploidy. Human Reproduction, 2012; DOI: 10.1093/humrep/des170