Egg freezing
In egg freezing, eggs are collected from the ovaries after hormone stimulation, frozen unfertilised and stored for possible later use. This page explains who it is generally considered for, how a cycle runs, what later use involves, and what the evidence says about the chance of a birth.
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What egg freezing is
Egg freezing (oocyte cryopreservation) means collecting eggs from the ovaries, freezing them unfertilised and storing them. If they are needed later, they are thawed and fertilised with sperm in the laboratory, and an embryo is transferred to the uterus.
In embryo freezing, the eggs are fertilised first, so sperm is needed and the embryo comes from two people.
Who it is generally considered for
- Before a treatment that may harm fertility. Some cancer treatments, such as chemotherapy and radiotherapy to the pelvis, can damage the ovaries, and ESHRE also names conditions other than cancer, such as lupus, endometriosis and Turner syndrome. NICE (2026) advises that fertility preservation be discussed before any treatment likely to impair fertility, and that egg or embryo freezing be offered as appropriate.
- For non-medical reasons. Some women who are not ready to try for a pregnancy freeze eggs because fertility declines with age; the American Society for Reproductive Medicine (ASRM) calls this planned egg freezing.
ESHRE advises that suitability be decided case by case, after full information on the chances, risks and possible long-term consequences.
How a cycle runs
Up to egg collection, the steps are those of an IVF cycle, described on the IVF and ICSI page; preparing for IVF covers the months before.
Stimulation and egg collection. Hormone medicines bring several eggs to maturity while the response is monitored, which the HFEA puts at around two to three weeks. The eggs are then collected under sedation or a general anaesthetic.
Vitrification. A protective solution is added and the eggs are cooled very rapidly, then stored in liquid nitrogen. The ASRM (2021) notes that more eggs survive this method than the older slow freezing.
Using the eggs later
The eggs are thawed, and those that survive are each injected with a single sperm (ICSI) because, as the HFEA explains, freezing toughens the outer coat of the egg. An embryo is then transferred to the uterus as in IVF; after your embryo transfer describes what follows.
What the evidence says about the chance of a birth
The HFEA states that egg freezing is no guarantee of a baby. Two things weigh most: the age at freezing and the number of eggs stored.
Age at freezing. On limited data, the ASRM guideline (2021) concludes that birth rates are higher when eggs are frozen at a younger age, and that the data are insufficient to name an optimal age.
Number of eggs. Each egg carries a small chance, so numbers matter, and the ASRM guideline notes that more eggs are needed when they are frozen at an older age. The HFEA notes that most women under 38 have around 7 to 14 eggs collected in a cycle, fewer when ovarian reserve is low, and the ASRM Ethics Committee (2023) that more than one cycle is often needed.
How firm the evidence is. Few women have yet used their frozen eggs, and the ASRM regards the evidence as insufficient to predict a woman's own chance of a birth or the number of eggs she needs.
Questions worth asking your doctor
- 1
How many eggs is a cycle likely to yield for me?
AMH and the antral follicle count give an estimate, which shows whether one cycle is likely to be enough.
- 2
What is the clinic's own experience with thawed eggs?
The ASRM Ethics Committee advises clinics to share their own figures for egg survival after thawing and for births, or to say if they have none yet.
- 3
Eggs, embryos or both?
ESHRE advises that a woman with a partner be given the option of freezing unfertilised eggs, or some eggs and some embryos.
Dr. Ghina Shami
Risks and limits
Ovarian hyperstimulation syndrome (OHSS). The ovaries can over-respond to the medicines and become enlarged and painful. The HFEA notes that around a third of women have mild OHSS and that severe OHSS, in very rare cases, can be life-threatening. The ASRM Ethics Committee notes that the risk is lower, although not absent, when no embryo is transferred in the same cycle.
Egg collection. Infection, bleeding and injury to the bowel are rare complications.
Eggs lost along the way. Not every egg survives thawing, not every surviving egg fertilises, and not every fertilised egg becomes an embryo that can be transferred.
No certainty. Frozen eggs may not lead to a birth, and the ASRM warns of the false sense of security they can give. Pregnancy at an older age also carries more risk for mother and baby, whatever the age of the eggs.
What is not yet known. From a small number of births, the ASRM found that the health of babies at birth appears similar whether the eggs were frozen or fresh; long-term data are incomplete.
Storage. How long eggs may be stored, and what happens to unused eggs, is set by UAE law and explained by the treating clinic.
Common questions
Does the age at freezing matter?
Yes. On limited data, the ASRM guideline found that birth rates are higher when eggs are frozen at a younger age, but that the data do not allow an optimal age to be named. Its Ethics Committee adds that eggs frozen early are less likely ever to be used.
How many eggs are needed?
No number is certain to be enough. Fewer eggs lead to a birth when they are frozen at an older age, so more are needed, and the ASRM considers the evidence insufficient to give a woman a firm number.
How long can eggs stay frozen?
The time limit is set by UAE law, and the treating clinic explains it. Medically, the HFEA states that there is not enough evidence to say for sure whether longer storage affects eggs.
Evidence basis: This page is based on the ESHRE guideline on female fertility preservation (2020), the ASRM guideline (2021) and Ethics Committee opinion (2023) on planned egg freezing, the 2026 NICE fertility guideline and HFEA patient information; the evidence on births from frozen eggs comes mostly from observational studies, and where the evidence is limited, the page says so.
References
- Egg freezing, HFEA (Human Fertilisation and Embryology Authority) (2016) — hfea.gov.uk
- ESHRE guideline: female fertility preservation, ESHRE, Human Reproduction Open (2020) — doi:10.1093/hropen/hoaa052
- Evidence-based outcomes after oocyte cryopreservation for donor oocyte in vitro fertilization and planned oocyte cryopreservation: a guideline, American Society for Reproductive Medicine (Practice Committee) (2021) — asrm.org
- Planned oocyte cryopreservation to preserve future reproductive potential: an Ethics Committee opinion, American Society for Reproductive Medicine (Ethics Committee) (2023) — asrm.org
- Fertility problems: assessment and treatment, NICE (guideline NG257) (2026) — nice.org.uk
- Risks of fertility treatment, HFEA (2016) — hfea.gov.uk
Written and reviewed by Dr. Ghina Shami, Consultant, Reproductive Medicine and Infertility · · How these pages are prepared