Egg freezing
Freezing eggs is only the first step in preserving reproductive potential. Between the eggs collected today and a baby born years later, there are several biological and clinical stages, and the number of eggs can reduce at each stage.
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A recent study of women who returned to use their previously frozen eggs reported an overall live birth rate of around 43%. Among women who had frozen their eggs before the age of 38 and later thawed 20 or more mature eggs, the live birth rate was over 70%. Egg freezing should therefore be discussed in terms of probability rather than guarantees.
The process begins with thawing the frozen eggs, followed by fertilisation and embryo development. Some embryos may reach the blastocyst stage and be suitable for transfer, after which implantation and pregnancy may occur. There can be natural attrition at each stage, which is why the number of eggs frozen should not be directly equated with the number of future embryos or pregnancies. Age at the time of freezing and the number of mature eggs stored are important factors in this process. These findings highlight how age at freezing and the number of mature eggs stored can influence outcomes, although individual results can vary. Egg quality, which is closely associated with age, the number of mature eggs frozen, and the laboratory’s thawing, fertilisation and embryo culture processes can all influence the eventual outcome. This is also why the number of eggs retrieved during one stimulation cycle should not be the only number discussed with a patient. The more meaningful conversation is around how many mature eggs were frozen, the patient’s age at freezing and the possibility that more than one cycle may sometimes be considered depending on individual circumstances and reproductive goals. Egg freezing does not preserve a fixed number of future pregnancies. It preserves the possibility of using younger eggs in the future, while the outcome still depends on each stage from egg warming to embryo development, implantation and pregnancy. (Author: Dr Sugata Mishra, Fertility Specialist, Birla Fertility & IVF , Kolkata) You use AI every day. Now get your AI Quotient. Take the AIQ test Get the latest Lifestyle News and more. Download the TOI app.
22 Sept 2026 | 15:01 When frozen eggs are used in the future, they first need to survive the warming process. Not every egg will survive. The surviving mature eggs are then usually fertilised through Intracytoplasmic Sperm Injection (ICSI), where a single sperm is injected directly into an egg. Every egg will not fertilise successfully, and among the resulting embryos, only some may continue developing into blastocysts suitable for transfer.