Cumulative newborn rates increase with the total number of transferred embryos according to an analysis of 15,792 ovum donation cycles

Cumulative newborn rates per total number of embryos needed to achieve a newborn provide an accurate idea of the likelihood of success in consecutive ovum donation cycles.

Nicolás Garrido, Ph.D., M.Sc., José Bellver, M.D., José Remohí, M.D., Pilar Alamá, M.D., Antonio Pellicer, M.D.

Volume 98, Issue 2 , Pages 341-346.e2, August 2012


To measure the success of in vitro fertilization (IVF) of donated ova according to cumulative newborn rates (CNBR) per number of embryos required to achieve at least one newborn (EmbR), considering in addition the relevance of age and infertility etiology.

Survival curves and Kaplan-Meier methods were employed to analyze CNBR with respect to the number of EmbR in a retrospective cohort of oocyte donation recipients.

University-affiliated infertility center.

Infertile couples undergoing IVF with oocyte donation.


Main Outcome Measure(s):
CNBR per EmbR.

The CNBR increased radically (up to 64.8%) between 1 and 5 EmbR, moderately (85.2%) between 5 and 15, and slowly thereafter, reaching a plateau at 15 embryos (92.4%) and peaking after 25 EmbR (96.8%), thus demonstrating that the chances of success vary as failed attempts accumulate. Patient age was not a negative factor, and indication for oocyte donation was also irrelevant to the outcome. The data showed an overall mean number of 2.6 embryo transfers and 5.8 transferred embryos per newborn.

The relationship between CNBR and number of EmbR provides pragmatic and exact information about the probability of success with oocyte donation, which is of obvious relevance to patient counseling.

  • NicoGarrido

    Any other question?

  • William Rods

    This manuscript is a more realistic approach to daily practice. In fact, to advice patients about chances of success per attempt has no meaning, since it is different to replace 2 or 4 embryos at once. here we have better tables and figures to advice our patients. Congratulations!

  • William Rods


  • Micah Hill

    Thank you for your reply and the comment on intent to treat makes sense. Congratulations on the nice study!

  • NicoGarrido

    Dear Dr Hill,
    thank you for your comments
    regarding the question about when to transfer on d3 or blastocysts, I believe it is a tricky issue given that what this approach do not compute is failed embryo transfer.
    We are preparing a new model considering this improvement in the model.
    I mean with this that the rates per transfer are higher (obvious) in blastocyst stage, but there are more cancellations when attempting to reach this stage.
    This means that the results should be measured per intention to treat: from the beggining of the cycle having decided when to transfer, regardless the embryo’s quality.
    The decision to move to blast transfers in donor’s cycles will depend on several parameters, then.
    All the best

  • Micah Hill

    This is a very nice article and I agree that the results have many applications, such as patient counseling and donor split cycles. Over 90% of the donor cycles were cleavage stage transfers. Given that blastocyst transfers overall did about 5% better and had a better curve at almost every data point in supplemental figure 2, I am curious if this particular center is moving to more blast transfers in donor cycles?

  • NicoGarrido

    Thanks Dr Brezina!
    let me know if I can be of further assistance

  • Paul Brezina

    This is a very interesting paper that is highly applicable to patient counseling. I will definitely use this data to better educate my patients.

  • NicoGarrido

    Hi everyone!
    I hope our work was useful for your daily practice, and I will be more than happy of answering your questions in the best way I can.
    Congratulations to both Co-editors in chief and also Dr Palter for having built this exciting way to share knowledge and interaction between readers and authors.
    All the best
    Nicolás Garrido

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