Test Detects Pregnancy Potential of Embryo Before IVF

A new study has shown that a test for a genetic marker can be used to identify which embryos used in in vitro fertilization (IVF) are most likely to result in pregnancy. The study was posted on the The Journal of Reproductive Biomedicine website (www.rbmonline.com) on May 5, 2004.

This test, performed on culture media surrounding early embryos, would not only double the success rate of IVF, say scientists, but would also reduce the large number of multiple pregnancies and their associated risks and costs. The study was conducted on 201 women aged 28-44, who subsequently underwent embryo transfer with fresh 7-10 cell embryos, transferred 72 hours after retrieval.

The one-year study indicates that individually cultured embryos producing sufficient concentrations of a genetic marker called sHLA-G (soluble, human leukocyte antigen-G) to give previously infertile women a better-than-60% pregnancy success rate, which is double the current success rates for IVF. The presence of high levels of sHLA-G had a positive predictive value greater than 70% in women under 39, and more than 50% in women 39-44.

"Ever since the birth of the first test tube baby in 1978, the desire to optimize pregnancy rates has prompted many IVF specialists to transfer more rather than fewer embryos, keeping their fingers crossed that only one will attach to the uterine lining,” noted lead author, Dr. Geoffrey Sher, clinical professor of obstetrics and gynecology at the University of Nevada School of Medicine (Las Vegas, USA; www.unr.edu/med) and founder of the Sher Institutes for Reproductive Medicine (SIRM, New York, NY, USA).

According to the U.S. Centers for Disease Control and Prevention (Atlanta, GA,USA), more than 35% of babies born as a result of IVF and other fertility techniques in 2001 were twins or more.

SIRM researchers have been able to develop a noninvasive embryo marker expression test (EMET) to measure the concentration of sHLA-G produced by each individual early embryo in culture. The marker is expressed by some embryos into the fluid in which they are grown. It appears to influence the maternal in utero immune response to an early embryo, and a direct ratio has been discovered between its presence in higher concentrations and the ability of that embryo to result in a successful pregnancy.

The new sHLA-G test will also determine whether a patient is unlikely to conceive through IVF before an attempt is ever made, saving time, concern, and investment. EMET may also help establish a standard by which new fertility drugs and protocols may be assessed to promote U. of Nevada Med. School development of good quality embryos.

Since at SIRM, each egg is fertilized and cultured into an embryo separately, the process allows for individual assessment of each embryo. Each sHLA-G assay in the study was performed 46 hours from the moment of fertilization and one day in advance of embryo transfer. Earlier, it took two days for a doctor to gauge the sHLA-G level of the embryo. Now researchers have found a way to reduce this time to only about two hours.





Related Links:
Journal of Reproductive Biomedicine website
SIRM
U. of Nevada Med. School