Clinical factors associated with live birth after single embryo transfer

Female age and blastocyst expansion are associated with live birth in patients undergoing SET. Many other clinical factors including obesity do not appear to affect SET outcome.

Jessica D. K. Kresowik, M.D., Amy E. T. Sparks, Ph.D., Bradley J. Van Voorhis, M.D.

Volume 98, Issue 5, Pages 1152-1156, November 2012


To identify patient, cycle, and retrieval characteristics associated with embryo implantation and live birth in patients undergoing SET

Analysis of prospectively collected IVF database.

Academic IVF program.

All patient cycles meeting criteria for SET between June 2004 and September 2010.


Main Outcome Measures:
Clinical pregnancy and live birth.

Single embryo transfer was performed in 438 cycles, resulting in a clinical pregnancy rate of 76.2% and a live birth rate of 66.8% per transfer. Clinical pregnancy was associated with younger female age, ≥58% mature (metaphase II) oocytes at the time of retrieval, and increasing blastocyst expansion. Ongoing pregnancy was associated with younger female age and more advanced blastocysts. A diagnosis of uterine factor was negatively associated with live birth.

Even in a favorable prognosis population, younger female age is associated with clinical pregnancy and live birth. Although all patients underwent blastocyst transfer, expanded and hatching blastocysts were strongly associated with pregnancy and live birth. A diagnosis of uterine factor was the only infertility diagnosis found to affect live birth after SET. Obesity did not negatively impact SET outcome. These findings may assist physicians in determining the best candidates for SET.

  • Congratulations for your work. To have a mandatory policy of SET in a group of patients of a private center is very difficult and to achieve 66.8% of live birth rate after SET, even in a good prognosis of patients, are excellent results. In a RCT we will send to this journal next month, we measured, too, the rate of patient’s refusal in a similar good prognosis patient of our private center and we found that 1/3 of them finally refused to perform SET. Did you measure the rate of patient’s refusal to eSET? Thank you very much.

    • Jessica Kresowik

      Thank you for your comments. We actually discuss our policy for single embryo transfer qualification at the new IVF visit and tell our patients that if they meet those requirements they will only have one embryo transferred. The patients are not given a choice on the day of transfer if they meet the criteria and we have had excellent acceptance of our policy. We reviewed our data prior to implementing the policy and we have not had any change in clinic volume since this was started.

  • Micah Hill

    Congratulations for another nice paper from the University of Iowa group on single embryo transfer. I appreciate the significant publications and efforts from this group in
    pushing the SET discussion in the US.

    First, I was curious if these findings have changed your algorithm at all or is your SET policy the same after this paper? Specifically with uterine factor, it seems that only significant mullerian anomalies negatively affected your live birth rates. However, these patients are a group that twin gestation may put their pregnancy at very high risk. Conversely the patients with fibroid and polyps removal had good live birth rates of 52%. So it seems that severe uterine factor should perhaps still get SET from an obstetric standpoint and the “mild” uterine factor should also still get SET from a success standpoint.

    Second, you point out the differences between your paper and the Alstrohm paper with regards to the effect of the TE and ICM grading and outcomes. I was curious if perhaps this was a power issue, since their paper had over 1000 SET cycles. Could you provide the OR and CI for your univariate analysis on TE and ICM? I was curious what the actual numbers were.

    • Jessica Kresowik

      We appreciate your insight and comments on our paper. As you point out, due to the risk of multiple gestation in patients with uterine anomalies we still perform SET on these patients despite their decreased rate of live birth. We also consider those patients with mild uterine factor to qualify for SET as subgroup analysis did not reveal a decrease in live birth in this patient population.
      Regarding the TE and ICM grading, our sample size was smaller and overall pregnancy rate higher, thus making a significant difference in the outcome based on these parameters more difficult to detect. Additionally, embryos with a C grade were included in the Alstrohm analysis, where our patients would have undergone double embryo transfer with this grade. Our numbers were as follows:

      Day 5 Troph Clinical Preg No Clinical Preg OR 95% CI p-value
      A 218 (66%) 67 (64%) 1.04 0.66 – 1.64 0.871
      B 116 (34%) 37 (36%) 0.96 0.61 – 1.54 0.871
      Day 5 ICM
      A 237 (71%) 67 (64%) 1.35 0.85 – 2.15 0.211
      B 97 (29%) 37 (36%) 0.74 0.47 – 1.19 0.211

      • Micah Hill

        Thank you for the reply and especially for providing more information. It is very helpful for me!

  • laurenwroth

    This is wonderful article highlighting the success of eSET in the appropriately selected population. I think it gives really important clinical information that will help us counsel patients.

    • Jessica Kresowik

      Thank you!

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