Undergoing Egg Freezing is a safe and established treatment but it is important that you understand your chances of success when you come to use your frozen eggs (oocytes) in the future.
Using markers of ovarian reserve, such as Anti-Mullerian Hormone (AMH) and Antral Follicle Count (AFC) on ultrasound, your Fertility Specialist will optimise your treatment plan to maximise the number of good quality mature eggs that can be retrieved. Only mature eggs are frozen and not all eggs that are retrieved are mature.
In order to increase your chances of having a baby in the future, your Fertility Specialist may recommend that you undergo more than one Egg Freezing Cycle.
When you return in the future to use your eggs, they will be warmed and thawed and then fertilised using intracytoplasmic sperm injection (ICSI) where a single sperm is injected into each egg.
Once an egg is fertilised it is called an embryo. The embryos are developed in the lab for 5 days (to the blastocyst stage) and then transferred into the uterus. Usually only one blastocyst is transferred at a time and the other good quality embryos are frozen.
Egg freezing is not a guarantee of a baby, but it is a good option for providing women with additional reproductive choices.
An easily understood metric for success is the chance of a baby according to age and how many eggs are frozen. Based on your testing, your Fertility Specialist will be able to give you a realistic expectation of how many eggs may be collected from your cycle. It is not just about number but also about quality. The younger you are when you freeze the eggs, the better quality those eggs will be.
Egg freezing, although safe and well-established, is a relatively new treatment and as yet there is not a large amount of data on live births from women who have come back to use their frozen eggs.
Recent medical studies by respected researchers have indicated that IVF outcomes using frozen eggs are comparable to the outcomes when fresh eggs are used (Cobo et al 2010; Rienzi et al 2010; Doyle et al 2016; Rienzi et al 2016).
The following statistics was taken from a respected medical journal, Human Reproduction, and published in 2017. It is an evidence-based counselling tool developed for women to predict the likelihood of a live birth based on age and the number of eggs frozen. It is a mathematical model derived from a surrogate population of patients who have a normal ovarian reserve.
Live birth predictions by age and number of mature eggs retrieved. Each curve shows the percent likelihood that a patient of a given age will have at least one live birth. Adapted from Goldman et al. “Predicting the likelihood of live birth for elective oocyte cryopreservation: a counselling tool for physicians and patients”. Human Reproduction, 2017.
According to this model, women aged 34, 37 or 40 with 20 mature eggs frozen would be expected to have a 90%, 75% and 53% likelihood respectively of having at least one live birth. Alternatively, women aged 34, 37 or 42 would need to freeze 10, 20 and 61 oocytes respectively to have a 75% likelihood of having at least one live birth.
In a different study, again published by a respected medical journal (Fertility and Sterility) graphs were established to predict probabilities of having a least one live-born child according to the number of mature eggs frozen in a certain age range.
Predicted probability of having a live birth according to age and the number of eggs frozen. Adapted from Doyle et al. “Successful elective and medically indicated oocyte vitrification etc”, Fertility and Sterility, 2016.
There is no age cut-off for freezing eggs as it is really a patient’s own decision. However, due to the statistically low chances of success, we do not recommend egg freezing for women over the age of 40. Between the ages of 38 and 40, it is a grey zone of recommendation. It would depend upon how many eggs can be frozen which can be predicted with some level of accuracy from ovarian reserve tests such as AMH.
There are a number of variables to consider, however. During your consultation, your Fertility Specialist will provide you with detailed information about your projected individual success rate.
Cobo A et al. “Use of cryo-banked oocytes in an ovum donation programme: a prospective, randomized, controlled, clinical trial.” Human Reproduction 2010; 25: 2239-46.
Rienzi L et al. “Embryo development of fresh “versus” vitrified metaphase II oocytes after ICSI: a prospective randomized sibling-oocyte study.” Human Reproduction 2010; 25: 66-73.
Doyle J et al. “Successful elective and medically indicated oocyte vitrification and warming for autologous in vitro fertilisation, with predicted birth probabilities for fertility preservation according to number of cryopreserved oocytes and age at retrieval.” Fertility and Sterility 2016; 105: 459-66.
Rienzi L et al. “Oocyte, embryo and blastocyst cryopreservation in ART: systematic review and meta-analysis comparing slow freezing versus vitrification to produce evidence for the development of global guidance.” Human Reproduction Update 2016.
Goldman R et al. “Predicting the likelihood of live birth for elective oocyte cryopreservation: a counselling tool for physicians and patients.” Human Reproduction 2017; 32: 853-59.