Using Your Frozen Eggs: What the Process Involves

Using frozen eggs means completing the second half of an IVF cycle. The eggs are thawed, fertilized with sperm in the laboratory, cultured for five to six days, and one resulting embryo is transferred into the uterus. Your own body is prepared for that transfer with medication, so the timing is planned around your cycle rather than around when the eggs are thawed. Not every egg survives thawing, and not every fertilized egg becomes a transferable embryo, which is why the number stored matters.

What are the steps?

1. Assessment. Your current health, uterus and hormone levels are reviewed, and your partner's sperm or donor sperm is arranged. Time has usually passed since freezing, so this is not a formality.
2. Preparing the uterine lining. Medication builds the endometrium to receive an embryo, monitored by ultrasound.
3. Thawing. The eggs are warmed under controlled conditions. Not all will survive; your clinic should tell you how many did.
4. Fertilization. Surviving eggs are fertilized, generally using ICSI. This is a genuine technical requirement rather than an addition: the outer layer of the egg changes during freezing and thawing, which can prevent conventional fertilization.
5. Embryo culture. Fertilized eggs are grown for five to six days. Not all will develop.
6. Embryo transfer. One embryo is transferred; any others may be frozen.
7. Pregnancy test, around two weeks later.

Why numbers fall at each stage

This is the part worth understanding before you start, because it explains why the number of eggs you froze is not the number of chances you have.

Some eggs do not survive thawing. Of those that do, some do not fertilize. Of those that fertilize, some do not develop into transferable embryos. And a transferred embryo does not always implant. Each step reduces the number, and the losses compound.

None of this means the process is unreliable. It means the realistic question is not "how many eggs do I have" but "how many embryos is that likely to produce, and what happens if it is none". Ask us for our own figures at each step rather than general ones.

What affects the outcome?

• Your age when the eggs were frozen, which is the dominant factor. Eggs frozen at 32 remain eggs from a 32 year old.
• How many eggs were stored. See our article on how many eggs to freeze.
• Sperm quality at the time of fertilization.
• Your uterus and general health now, which is why the assessment at the start matters.

Note what is not on that list: your age now, as far as egg quality is concerned. Your current age affects the pregnancy itself and how it is managed, but the eggs are as they were when frozen.

What to ask before you start

• How many eggs are in storage, and how many are mature?
• What survival and fertilization rates does your laboratory see?
• What happens if no embryo is suitable for transfer?
• What does the thaw and transfer cycle cost, separately from what was paid for freezing?
• Is a fresh cycle worth considering alongside, given my age now?

We at Millennium IVF Clinic will review your stored eggs and set out what to expect. You can arrange a consultation with our team, and our article on what egg freezing involves covers the freezing side.

Frequently asked questions

Do all frozen eggs survive thawing?

No. Vitrification has improved survival considerably compared with older methods, but not every egg survives. Ask us for our own rate.

Do I need ICSI to use frozen eggs?

Generally yes. Freezing and thawing changes the outer layer of the egg, which can prevent conventional fertilization, so a sperm is injected directly.

Does my current age affect the eggs?

Not the eggs themselves, which are as they were when frozen. Your current age affects the pregnancy and how it is monitored.

How long can eggs stay in storage?

Storage in Thailand is governed by the Protection of a Child Born by Medically Assisted Reproductive Technology Act B.E. 2558 (2015). The Act itself does not fix a maximum storage period: section 42 delegates the rules for depositing, using and terminating stored sperm, eggs and embryos to the Medical Council of Thailand, so ask us for the period currently in force and what you need to sign to maintain storage. Two points in the Act are worth knowing in advance. Section 41 prohibits importing or exporting sperm, eggs or embryos, so material stored in Thailand cannot be moved to another country. And under section 43, if the person whose sperm or eggs are stored dies, they may not be used unless written consent was given beforehand, and then only for the treatment of a surviving spouse.