Preimplantation Genetic Diagnosis Reduces Older Women's Chances Of Pregnancy

Preimplantation Genetic Diagnosis

Using preimplantation genetic diagnosis to screen for potentialbirth defects reduces the likelihood of an older woman becomingpregnant through in vitro fertilization by one-third, according to astudy published Thursday in the New England Journal of Medicine, the Los Angeles Times reports.PGD involves removing a single cell from a three-day-old embryo to testfor potential birth defects and then implanting the embryos most likelyto result in a healthy infant, according to the Times.

Sebastiaan Mastenbroek of the Academic Medical Center at the University of Amsterdamand colleagues enrolled 408 women ages 35 to 41. Half of the womenreceived IVF with PGD and the other half received IVF without PGD. Allof the women in the study went through as many as three IVF cycles, theTimes reports (Maugh, Los Angeles Times,7/5). Among the women who received PGD, 25% reached the 12th week ofpregnancy, compared with 37% of the women who did not receive PGD. Thebirth rate was 24% among women receiving PGD and 35% among women notreceiving PGD, the study found (Armstrong, Wall Street Journal, 7/5).

According to the Times,only a few thousand PGD procedures are performed annually, althoughsome researchers say the procedure has been increasing by as much as30% per year (Los Angeles Times, 7/5). About seven in 10fertility clinics nationwide offer PGD to women undergoing IVF at acost of $3,000 to $5,000, according to the Journal (Wall Street Journal, 7/5).

The study did not examine why PGD reduces women's chances of pregnancy, London's Independentreports. According to Mastenbroek, it is possible that PGD "hampers thepotential of an embryo to successfully implant." According to the Independent, PGD also might not identify all chromosomal abnormalities, leading to possible implantation of embryos with abnormalities.

Reaction

The researchers recommended that PGD should not be offered routinely to women undergoing IVF (Connor, Independent,7/5). The study "rings the death knell" for using PGD to routinelyscreen older women, Richard Scott, founder of the IVF clinic chain Reproductive Medicine Associates,said. However, the procedure is still recommended to test for specificgenetic defects that the mother and father are known to carry, the Times reports (Los Angeles Times, 7/5).

John Collins, a professor at McMaster University, in a NEJM editorialaccompanying the study wrote that PGD "appears to do no more thaninterfere with the natural screening and selection process." Collinsadded that the procedure should not be targeted toward older women.Kathy Hudson, director of the Genetics and Public Policy Centerat Johns Hopkins University, said that more research is needed into theeffectiveness of PGD, adding, "The question is: Are these results trulygeneralizible to other clinics?" (Wall Street Journal, 7/5).

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