BWH Egg Freezing Counseling Tool (EFCT)
This calculator is not externally validated, and as such, should be used with caution.
Use in women age 24–44 years undergoing fertility counseling.
Patients seeking fertility preservation with elective egg freezing.
- Uses a woman’s age at egg retrieval and the number of mature eggs frozen to predict the probability of having at least one, two or three live births.
- Since limited data exist regarding live births following elective egg freezing, the BWH Egg Freezing Counseling Tool was developed from a surrogate population of presumably fertile women (egg donor, male-factor and tubal-factor only infertility).
- No number of frozen eggs can guarantee a live birth.
- IVF stimulation cycles produce a variable number of eggs, even among women of similar ages. Older women typically obtain fewer eggs per stimulation cycle.
- May be less reliable for women ≥39 years old.
- May overestimate live birth rates for women undergoing non-elective egg freezing for medical reasons, such as cancer.
- Data are retrospective and from a single academic institution in an insurance-mandated state.
- Individual IVF clinics with different thaw survival and live birth rates may need to modify and customize this model.
- Has yet to be prospectively validated.
- Predicts likelihood of having at least one, two, or three live births using only two data points.
- Incorporates likelihood that an embryo will have normal number of chromosomes.
- Helps determine whether undergoing additional egg freezing cycles would result in a meaningful increase in likelihood of having a live birth.
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Decisions about egg freezing should be made by the patient in conjunction with her physician, considering patient-specific characteristics.
p(Livebirth) = 1 – [1 – 0.6 × p(Euploid) × p(Blast)] ^ (Number of mature eggs)
p(Blast) = 0.95 × exp(2.8043 – 0.1112 × Age) if Age <36
p(Blast) = 0.85 × exp(2.8043 – 0.1112 × Age) if Age ≥36
p(Euploid) is from table below
Note: number of mature eggs assumes 95% survival of thawed eggs (85% if age is ≥36 years).
Facts & Figures
Egg donors (for reference)
Note: In the study, ages 24–35 were grouped together, as fertility is fairly stable up to age 35 and begins to decrease appreciably after that age.
The BWH Egg Freezing Counseling Tool was developed by Goldman and Fox et al at Brigham and Women’s Hospital based on a data set of 520 patients who underwent first fresh autologous cycles using ICSI (intracytoplasmic sperm injection).
Poisson regression was used to predict the proportion of mature eggs that ultimately developed into usable blastocysts, using patient age as the primary parameter.
Estimates of live birth rates were found to be similar to other models, including by Doyle et al (2016), which used broader age groups instead of age by individual years.
The authors assumed that 60% of euploid blastocysts, on average, would ultimately result in a live birth based on published data, but the actual rate is known to vary among IVF clinics (Harton 2013).
Original/Primary ReferenceGoldman RH, Racowsky C, Farland LV, Munné S, Ribustello L, Fox JH. Predicting the likelihood of live birth for elective oocyte cryopreservation: a counseling tool for physicians and patients. Hum Reprod. 2017;:1-7.
Other ReferencesDoyle JO, Richter KS, Lim J, Stillman RJ, Graham JR, Tucker MJ. Successful elective and medically indicated oocyte vitrification and warming for autologous in vitro fertilization, with predicted birth probabilities for fertility preservation according to number of cryopreserved oocytes and age at retrieval. Fertil Steril. 2016;105(2):459-66.e2.Harton GL, Munné S, Surrey M, et al. Diminished effect of maternal age on implantation after preimplantation genetic diagnosis with array comparative genomic hybridization. Fertil Steril. 2013;100(6):1695-703.
About the Creator
Randi Goldman, MD, is a clinical fellow in reproductive endocrinology and infertility at Brigham and Women's Hospital and Harvard Medical School. She completed her training in obstetrics and gynecology at Brigham and Women's Hospital/Massachusetts General Hospital and Harvard Medical School. Dr. Goldman’s primary research and clinical interests include reproductive health and the assessment and treatment of infertility.
To view Dr. Randi Goldman's publications, visit PubMed
About the Creator
Janis H. Fox, MD, is an assistant professor in obstetrics, gynecology and reproductive biology at Harvard Medical School. She is also an attending reproductive endocrinologist in the Center for Infertility and Reproductive Surgery at Brigham and Women’s Hospital. Her clinical practice focuses primarily on infertility and assisted reproductive technologies. Dr. Fox has published on factors contributing to success and failure following in vitro fertilization.
To view Dr. Janis Fox's publications, visit PubMed
- Malinda Lee, MD