Genetic Diagnosis of Embryos Found Bad IVF Medicine
July 6, 2007 – 12:51 pm | posted in GeneticsIn older women seeking in-vitro fertilization, genetic diagnosis of embryos before implantation is a waste of time, with a harmful fallout, said investigators here.
Action Points
* Explain to interested patients that in-vitro fertilization in women of advanced maternal age — from 35 through 41 — has a low success rate.
* Note that preimplantation genetic diagnosis — taking cells from an embryo for genetic screening — had been proposed as a way to improve the odds.
* Explain that this large randomized controlled trial, however, shows that the procedure actually worsens the odds of in-vitro fertilization resulting in a pregnancy or live birth in these women.
In a randomized, double-blind controlled trial, women who underwent preimplantation genetic screening had significantly fewer on-going pregnancies and live births than those who did not have the procedure, Sjoerd Repping, Ph.D., of the Academic Medical Center in Amsterdam, reported in the July 5 issue of the New England Journal of Medicine. The study results were presented simultaneously at the European Society of Human Reproduction and Embryology meeting here.
In general, IVF success rates for women ages 35 through 41 are “disappointingly low,” which has led to the suggestion that their embryos should be screened preimplantation for chromosomal abnormalities, noted Dr. Repping and colleagues.
The findings “argue strongly against” genetic screening in these women, Dr. Repping and colleagues said.
The researchers randomized 408 women to get three cycles of IVF with or without preimplantation genetic screening. The primary outcome of the study was an on-going pregnancy at 12 weeks, while a secondary outcome was live births.
The study found:
* The ongoing-pregnancy rate was 25% in the women assigned to preimplantation genetic screening, significantly lower than the 37% in those in the control group.
* The rate ratio was 0.69 with a 95% confidence interval from 0.51 to 0.93, which was significant at P=0.01.
* The live-birth rate was also significantly lower (P=0.01) for women in the screening group — 25% compared to 35%.
* The rate ratio was 0.68 with a 95% confidence interval from 0.50 to 0.92.
The study also found the rates of biochemical pregnancy and clinical pregnancy were significantly lower (P=0.008 and P=0.003, respectively) among those in the screening arm.
In an accompanying editorial, John Collins, M.D., of Dalhousie University in Halifax, Nova Scotia, said that for every nine women who use three cycles of IVF, there would be one more live birth if genetic screening had not been used, on the basis of data from the study.
Because about 8% of pregnancies established by IVF are lost after 12 weeks, the use of on-going pregnancy at 12 weeks as the primary outcome “in my opinion is a design flaw,” Dr. Collins said.
Nevertheless, he added, live births were analyzed as a secondary outcome and the results are sufficiently strong to rule out genetic screening for chromosomal abnormalities “solely because of advanced maternal age.”
For other indications — such as recurrent unexplained miscarriage and recurrent implantation failure — the issue is still up in the air, he said, but the procedure should only be used in clinical trials designed to answer the question.
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