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J Assist Reprod Genet. 2016 Apr;33(4):481-8. doi: 10.1007/s10815-016-0664-x. Epub 2016 Feb 6.

Serum estradiol:oocyte ratio as a predictor of reproductive outcome: an analysis of data from >9000 IVF cycles in the Republic of Ireland.

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Department of Obstetrics and Gynecology, Tufts Medical Center, Boston, MA, USA.
Sims IVF/The Sims Institute, Dublin, Ireland.
Reproductive Research Section, Center for Advanced Genetics, 3144 El Camino Real, Suite 106, Carlsbad, CA, 92008, USA.
Molecular and Applied Biosciences Department, Faculty of Science & Technology, University of Westminster, London, UK.
Division of Reproductive Endocrinology, Rotunda IVF, The Rotunda Hospital, Dublin, Ireland.
Department of Obstetrics & Gynaecology, School of Medicine, Royal College of Surgeons in Ireland, Dublin, Ireland.



The purpose of this study was to evaluate the serum estradiol (E2) per oocyte ratio (EOR) as a function of selected embryology events and reproductive outcomes with IVF.


This retrospective analysis included all IVF cycles where oocyte collection and fresh transfer occurred between January 2001 and November 2012 at a single institution. Patients were divided by three age groups (<35, 35-39, and ≥40 years) and further stratified into nine groups based on EOR (measured in pmol/L/oocyte). Terminal serum E2 (pmol/mL) was recorded on day of hCG trigger administration, and fertilization rate, cleavage rate, number of good quality embryos, and reproductive outcomes were recorded for each IVF cycle.


During the study interval, 9109 oocyte retrievals were performed for 5499 IVF patients (mean = 1.7 cycles/patient). A total of 63.4 % of transfers were performed on day 3 (n = 4926), while 36.6 % were carried out on day 5 (n = 2843). Clinical pregnancy rates were highest in patients with EOR of 250-750 and declined as this ratio increased, independent of patient age. While the odds ratio (OR) for clinical pregnancy where EOR = 250-750 vs. EOR > 1500 was 3.4 (p < 0.001; 95 % CI 2.67-4.34), no statistically significant correlation was seen in fertilization, cleavage rates or number of good quality embryos as a function of EOR.


Predicting reproductive outcomes with IVF has great utility both for patients and providers. The former have the opportunity to build realistic expectations, and the latter are better able to counsel according to measured clinical parameters. A better understanding of follicular dynamics and ovarian response to gonadotropin stimulation could optimize IVF treatments going forward.


Advanced reproductive technology; Estradiol:oocyte ratio; IVF; Outcome

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