Mother Talkers

Genetic screening has negative effect on IVF succes rate

by SwissClogs

Wed Jul 04, 2007 at 12:20:33 PM PDT

Research published in the New England Journal of Medicine today indicates that fertilised eggs that are tested for genetic disorders have a significantly (about 33%) smaller chance of leading to a successful pregnancy. The research was carried out at a Dutch University, which is why I found a report of their press release here (sorry, it's in Dutch).

The news report notes that preimplantation genetic screening (PGS) is not currently used in The Netherlands (apart from in this trial), but that it is fairly common in the US (2 out of 3 clinics offering IVF offer PGS as well), Belgium and the UK. PGS is also very expensive and generates substantial revenue for the clinics. People considering IVF should be aware of this.

The original paper is published in the NEJM here and accompanied by an editorial from which I quote below the fold. Note that both links are probably to subscribed content. If anyone is interested, please let me know in the comments, and I will find a way to send you the paper (I have access at work).

The editorial by John A. Collins, M.D. from McMaster and Dalhousie Universities in Canada notes that

The effectiveness of preimplantation genetic diagnosis has been accepted without randomized trials, because its success in reducing transmission of genetic diseases is self-evident.
...
Despite these drawbacks and the $3,000 to $5,000 cost of preimplantation genetic diagnosis in addition to the cost of the cycle of IVF or intracytoplasmic sperm injection, preimplantation genetic diagnosis is often considered a worthwhile alternative to prenatal testing and possible therapeutic abortion.
...
the results [of the study pblished today] suggest that for every nine women who are 35 to 41 years of age who plan three cycles of IVF or IVF and intracytoplasmic sperm injection, there will be one more live birth if preimplantation genetic diagnosis for aneuploidy screening is not performed.
...
Given the findings of Mastenbroek et al., preimplantation genetic diagnosis for aneuploidy screening should not be performed solely because of advanced maternal age.
...
Furthermore, the present results underscore other pressing research needs, such as avoiding the increased likelihood of aneuploidy associated with standard ovarian-stimulation routines and finding means of identifying which embryos are most likely to survive and become healthy singleton live births.

Tags: fertility, IVF, preimplantation screening, research (all tags)

Permalink | 7 comments

  • I suppose the cliched response would be (0 / 0)

    you can't fool Mother Nature. But that's just slapdash.

    This is an interesting development, and a reminder that screening alone, just for maternal age, is no panacea to having a healthy child. It reminds me of the back-and-forth debate here, as in other places, over amniocentisis. Age alone is not the sole trigger for possible birth defects.

    by Rachel on Wed Jul 04, 2007 at 03:34:40 PM PDT

  • Information is power. (0 / 0)

    I'm not for trying to steer people towards a particular treatment or procedure...rather I prefer to have ample amounts of information available that will allow them to make truly informed choices.  Doesn't make my kind popular with the medical professionals, but I gotta come down on the side of taking advantage of all the available sources of information.

    by tjb22 on Wed Jul 04, 2007 at 09:59:12 PM PDT

    • Couldn't agree more (0 / 0)

      personally I think it is wonderful that medical science has provided people with additional options. However, it is extremely important to be informed when making such choices. And this is a case where apparently not even the doctors offering the technique were all that informed...

      by SwissClogs on Fri Jul 06, 2007 at 02:08:46 AM PDT

      [ Parent ]

  • Is this the testing where (0 / 0)

    they take the 8-celled embryo and remove one of the cells for testing so that there are only 7 left to divide and form the baby? I always thought it was likely that this might have some effect, but I was sure someone had studied it.

    by shenanigans on Thu Jul 05, 2007 at 05:12:10 PM PDT

    • I'm not a doctor (0 / 0)

      or medical scientist, but from what I understand of the editorial and the article you may very well be right. The testing is certainly carried out at the 8-cell stage, and before implantation. It is not clear to me whether they actually remove a cell and I just don't know whether the chromosomal testing can be done without destroying the cell. But if one of the eight cells is basically taken away, my gut feeling would be that yes, chances of damage are significant. However, I suppose (and would hope) that this is not necessarily the case and that otherwise such a method would have been tested much more thoroughly before applying it widely.

      The article mentions some previous studies, but by the looks of it these were all very limited. The reasoning for doing this study

      The use of preimplantation genetic screening is increasingly common, in particular among women of advanced maternal age.5,6 It has even been suggested that preimplantation genetic screening will become a standard procedure for women undergoing IVF.6 Evidence supporting the use of preimplantation genetic screening, however, is limited. Observational studies comparing IVF with and without preimplantation genetic screening have shown that the use of preimplantation genetic screening is associated with higher implantation rates for transferred embryos but not with an increase in the rate of ongoing pregnancies per initiated cycle or per follicular aspiration. A recent Cochrane review of preimplantation genetic screening included only two trials (one available only in abstract form), and it reported no significant difference in ongoing-pregnancy rates between women undergoing IVF with and those undergoing IVF without preimplantation genetic screening. We conducted a multicenter, randomized, double-blind, controlled trial comparing ongoing-pregnancy rates after IVF with and without preimplantation genetic screening in women of advanced maternal age.

      In this study the primary outcome was considered positive if the pregnancy was viable and ongoing at 12 weeks, secondary outcomes were biochemical pregnancy (HCG-positive, ie pregnancy test), clinical pregnancy (ultrasound shows a gestational sac at 7 weeks), miscarriage, and live birth.

      The primary results

      Four hundred eight women (206 assigned to preimplantation genetic screening and 202 assigned to the control group) underwent 836 cycles of IVF (434 cycles with and 402 cycles without preimplantation genetic screening). The ongoing-pregnancy rate was significantly lower in the women assigned to preimplantation genetic screening (52 of 206 women [25%]) than in those not assigned to preimplantation genetic screening (74 of 202 women [37%]; rate ratio, 0.69; 95% confidence interval [CI], 0.51 to 0.93). The women assigned to preimplantation genetic screening also had a significantly lower live-birth rate (49 of 206 women [24%] vs. 71 of 202 women [35%]; rate ratio, 0.68; 95% CI, 0.50 to 0.92).

      by SwissClogs on Fri Jul 06, 2007 at 02:04:51 AM PDT

      [ Parent ]

    • my goodness (0 / 0)

      removing 12.5% of a blastocyst's matter!? I didn't know that's what happened. I would think it highly logical that this would cause some problems.

      by Rachel on Fri Jul 06, 2007 at 02:32:06 AM PDT

      [ Parent ]

      • Basically (0 / 0)

        at this stage, the embryo will divide and keep dividing - so for example identical twins can occur if the cells cleave apart. Technically you only need one cell.

        What makes me uncomfortable is leaving 7 cells, which is not a natural number of cells. Sure... it probably doesn't matter in the long term. But it feels weird to me that you'd want the embryo to get going again with a non-power of two number of cells.

        One of the possibilities is that all the cells aren't the same. This is a new area that they're realizing. For example, in horses, if you see a striped brindle pattern (as in dogs), most of those horses turn out to be chimeras, containing two separate genetic blueprints, as if a pair of fraternal twins fused. Really weird stuff.

        by shenanigans on Sat Jul 07, 2007 at 11:09:05 PM PDT

        [ Parent ]

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