LIVINGSTON, NJ and CAMBRIDGE, UNITED KINGDOM--(Marketwired - Dec 16, 2013) - A groundbreaking study examining chromosomal testing of embryos during IVF has shown that older women are just as likely to become pregnant as younger women if a genetically normal embryo is transferred.
Without this test, the chance of implantation decreases with advancing maternal age. Researchers at Reprogenetics have found that the rate at which embryos implant is the same regardless of maternal age in women 42 or younger when newer genetic screening techniques are used to screen and selectively transfer normal embryos during IVF. The study, published in Fertility and Sterility, found no relationship between maternal age and rates of implantation with the use of second-generation preimplantation genetic screening (PGS) techniques that test for chromosomal abnormalities via biopsy, followed by embryo transfer, suggesting a broader role for chromosome screening among women undergoing IVF.
"Based on the results of this study and building on other work, the role of PGS and selective embryo transfer can now be clearly established in the clinical setting," said Santiago Munné, Founder and Director of Reprogenetics. "This study shows that the majority of implantation failures and miscarriages in IVF can be attributed to advancing maternal age due to chromosomal abnormalities, and this effect can be reduced by replacing euploid (those with a normal number of chromosomes) embryos."
"This study is important because it demonstrates that pregnancy rates can be improved with novel chromosome screening techniques, and that any woman undergoing IVF, regardless of maternal age, can potentially benefit from screening," said Gary Harton, Associate Director of Product Marketing at BlueGnome, an Illumina company, and at the time of the study, a Laboratory Director at Reprogenetics. "The results were positive for both increasing implantation and, importantly, maintaining pregnancy to delivery," added Harton.
About the study
Following embryo biopsy at the cleavage stage (day 3 of embryo development) or the blastocyst stage (day 5/6 of embryo development), the relationship between maternal age, chromosome abnormality, implantation rate as well as the rate of pregnancy loss, were studied in a multicenter, retrospective trial. Investigators used cleavage stage biopsy to analyze 3,412 embryos and blastocyst stage biopsy to analyze 2,467 embryos. The percentage of abnormal embryos rose significantly as patient age increased for both cleavage stage and blastocyst stage biopsy. No significant association between implantation rates and maternal age was found for biopsy at either the cleavage stage or blastocyst stage (p < 0.1 and p < 0.2, respectively). In addition, no significant difference was found between pregnancy loss rates across all age groups for both embryo stages: 9.9% for cleavage stage biopsy and 7.9% for blastocyst stage biopsy. The incidence of clinical pregnancy loss was significantly less following transfer of embryos selected for euploidy than is observed in a general IVF population (p < 0.001). Ongoing pregnancy rate, defined by detection of a fetal sac on ultrasound, per transfer in the cleavage stage biopsy group ranged between 48.5% and 38.1% for women < 35 to 42 years of age, while for biopsy at the blastocyst stage, the ongoing pregnancy rate per transfer ranged between 64.4% and 54.5% respectively.
Fertility and Sterility is the official journal of the American Society of Reproductive Medicine (ASRM).
About Chromosomal Abnormalities and Genetic Embryo Screening
Chromosomal abnormalities are a leading cause of IVF failure, pregnancy loss, and in rare cases, abnormal pregnancy and live birth. Most abnormalities occur during the final stages of egg development and increase with maternal age. Recent evidence suggests that the eggs of younger patients also have a relatively high incidence of chromosomal abnormalities.
In PGS, embryos created through IVF are tested for chromosomal abnormalities prior to being transferred to a woman's uterus. The most advanced form of PGS, called array CGH (aCGH), allows clinicians to detect abnormalities in all 24-chromosomes in human embryos so that only healthy embryos are transferred during IVF. Normal embryos have a higher chance of implantation and the resulting pregnancies have a lower chance of miscarriage. The newer techniques are more robust, prone to fewer technical issues, and allow clinicians to grow, biopsy and test for chromosome abnormalities all the way to the blastocyst stage while still allowing for fresh embryo transfer. It is believed that biopsy at the blastocyst stage is less detrimental to embryo development.
Reprogenetics is the largest genetics laboratory in the US specializing in preimplantation genetic diagnosis (PGD/PGS), with over 26,000 performed procedures and hundreds of publications. Dr. Santiago Munné and Dr. Jacques Cohen founded Reprogenetics in 2000 after extensive experience in PGD and IVF. Reprogenetics offers a comprehensive and personalized service to its referring IVF centers and their patients. Genetic counselors are intricately involved in the process and interact routinely with patients pursuing all diagnostic tests and services to improve pregnancy outcomes.