Association between the number of eggs and live birth in IVF treatment: an analysis of 400 135 treatment cycles.

BACKGROUND While live birth is the principal clinical outcome following in vitro fertilization (IVF) treatment, the number of eggs retrieved following ovarian stimulation is often used as a surrogate outcome in clinical practice and research. The aim of this study was to explore the association between egg number and live birth following IVF treatment and identify the number of eggs that would optimize the IVF outcome. METHODS Anonymized data on all IVF cycles performed in the UK from April 1991 to June 2008 were obtained from the Human Fertilization and Embryology Authority (HFEA). We analysed data from 400 135 IVF cycles. A logistic model was fitted to predict live birth using fractional polynomials to handle the number of eggs as a continuous independent variable. The prediction model, which was validated on a separate HFEA data set, allowed the estimation of the probability of live birth for a given number of eggs, stratified by age group. We produced a nomogram to predict the live birth rate (LBR) following IVF based on the number of eggs and the age of the female. RESULTS The median number of eggs retrieved per cycle was 9 [inter-quartile range (IQR) 6-13]. The overall LBR was 21.3% per fresh IVF cycle. There was a strong association between the number of eggs and LBR; LBR rose with an increasing number of eggs up to ∼15, plateaued between 15 and 20 eggs and steadily declined beyond 20 eggs. During 2006-2007, the predicted LBR for women with 15 eggs retrieved in age groups 18-34, 35-37, 38-39 and 40 years and over was 40, 36, 27 and 16%, respectively. There was a steady increase in the LBR per egg retrieved over time since 1991. CONCLUSION The relationship between the number of eggs and live birth, across all female age groups, suggests that the number of eggs in IVF is a robust surrogate outcome for clinical success. The results showed a non-linear relationship between the number of eggs and LBR following IVF treatment. The number of eggs to maximize the LBR is ∼15.

[1]  A. Vail,et al.  Common statistical errors in the design and analysis of subfertility trials. , 2003, Human reproduction.

[2]  G. Letterie,et al.  The relationship of clinical response, oocyte number, and success in oocyte donor cycles , 2005, Journal of Assisted Reproduction and Genetics.

[3]  D. Seifer,et al.  Early and late presentation of the ovarian hyperstimulation syndrome: two distinct entities with different risk factors. , 1994, Human reproduction.

[4]  B. Mol,et al.  A systematic review of tests predicting ovarian reserve and IVF outcome. , 2006, Human reproduction update.

[5]  R. Batt,et al.  Estradiol production during controlled ovarian hyperstimulation correlates with treatment outcome in women undergoing in vitro fertilization-embryo transfer. , 2006, Fertility and sterility.

[6]  B. Joo,et al.  Serum estradiol levels during controlled ovarian hyperstimulation influence the pregnancy outcome of in vitro fertilization in a concentration-dependent manner. , 2010, Fertility and sterility.

[7]  B. Mol,et al.  The role of antimullerian hormone in prediction of outcome after IVF: comparison with the antral follicle count. , 2009, Fertility and sterility.

[8]  A. Kably Ambe,et al.  [Comparative analysis of pregnancy rate/captured oocytes in an in vitro fertilization program]. , 2008, Ginecologia y obstetricia de Mexico.

[9]  I. Craft,et al.  Utilization of retrieved oocytes as an index of the efficiency of superovulation strategies for in-vitro fertilization treatment. , 1997, Human reproduction.

[10]  P. Brinsden,et al.  Optimal follicle and oocyte numbers for cryopreservation of all embryos in IVF cycles at risk of OHSS. , 2008, Reproductive biomedicine online.

[11]  D. Valbuena,et al.  Increasing levels of estradiol are deleterious to embryonic implantation because they directly affect the embryo. , 2001, Fertility and sterility.

[12]  Human Fertilisation,et al.  Access anonymised HFEA data , 2010 .

[13]  S. Kim,et al.  Comparison of clinical characteristics between early and late patterns in hospitalized patients with ovarian hyperstimulation syndrome. , 2010, Fertility and sterility.

[14]  B. Tarlatzis,et al.  Mild ovarian stimulation for IVF: 10 years later. , 2010, Human reproduction.

[15]  Patrick Royston,et al.  Multivariable Model-Building: A Pragmatic Approach to Regression Analysis based on Fractional Polynomials for Modelling Continuous Variables , 2008 .