Understanding Egg Freezing and Fertility Preservation

Egg freezing, also known as oocyte cryopreservation, is a medical procedure that allows individuals to preserve their eggs (oocytes) for future use. Historically, this technique was developed primarily for cancer patients seeking to protect their fertility before chemotherapy or radiotherapy. However, egg freezing is increasingly chosen by people who wish to delay childbearing for various personal, professional or medical reasons. Below are key points to help clarify the process, its success rates, and other important considerations.

1. Success Rates of Freezing Eggs and Embryos

Embryo Freezing Survival Rate: It is often cited that frozen fertilised embryos (i.e., embryos created through IVF before freezing) can have a very high survival rate upon thawing, sometimes around 98%. Different clinics may report slightly different figures, but it is widely accepted that embryo survival rates after vitrification (the fast-freezing method) tend to be extremely high.
Egg Freezing Survival Rate: Unfertilised eggs have a somewhat lower survival rate upon thawing, often cited around 70–75%. Not every frozen egg will survive the warming process, and of those that do, not all will fertilise successfully.

2. The Age Factor

Decline in Fertility After 35: Fertility does drop significantly after age 35, largely due to decreased egg quality and quantity. By the time a woman reaches 45, natural conception rates are typically extremely low, and the chance of a successful IVF is also notably reduced. Some statistics point to around 55.6% success before 35, dropping to about 6.9% at 40, though these figures can fluctuate between studies.
Chromosomal Abnormalities: One of the major obstacles in achieving a successful pregnancy as eggs age is an increased risk of abnormal chromosome numbers (aneuploidy). This is why older eggs are less likely to lead to healthy, live births.

3. In-Body Versus In-Lab Fertilisation

Typical Pathway: Many clinics begin with less invasive procedures like IUI (Intrauterine Insemination), where sperm is introduced directly into the uterus, aiming for fertilisation within the body. This is sometimes colloquially referred to as “artificial insemination”.
IVF (In Vitro Fertilisation): If simpler methods fail or are deemed unsuitable, IVF is usually the next step. In IVF, eggs are retrieved and fertilised with sperm outside the body in a laboratory setting. The resulting embryos can then be transferred back into the uterus.

4. “Add-ons” in Fertility Treatment

“Add-ons” are optional techniques or treatments offered alongside standard IVF or egg-freezing protocols. Examples might include assisted hatching, embryo “glue,” time-lapse embryo imaging or additional hormonal treatments. Their efficacy and necessity can vary, and many add-ons still lack robust, long-term evidence of guaranteed benefit. Clinics should be transparent about these options, their costs and the existing evidence base.

5. Why Aim for Ten Eggs (or More)?

Not every egg collected will successfully fertilise or develop into a healthy embryo. A general example might be:

• You start with ten eggs.

• Perhaps four of these fertilise successfully.

• Ultimately, only two of those fertilised eggs might develop into genetically normal embryos suitable for transfer.

Hence, collecting more eggs initially increases the likelihood that at least a few healthy embryos will result.

6. Freezing Eggs Before Age 35

It is often recommended for individuals who wish to preserve their fertility for the future to consider egg freezing before the age of 35, as younger eggs are typically healthier and more likely to result in a successful pregnancy. Some clinics advise freezing about 20 eggs to maximise the chance of one or two successful pregnancies. These figures are not a strict rule but rather a guideline. The ultimate number of eggs needed can vary according to your personal circumstances, ovarian reserve and the clinics’ advice.

7. Transparency of the Process

Clinics should be open about every step of the procedure. You should feel fully informed about:

• Hormonal stimulation protocols.

• The surgical egg retrieval process (typically done under sedation with a transvaginal ultrasound-guided needle).

• How the eggs will be assessed, labelled and stored.

• How future embryo creation and transfers would be carried out.

8. How Eggs Are Retrieved

Eggs are accessed transvaginally, using a fine needle guided by ultrasound. This approach collects fluid from the ovarian follicles, which is then examined in the laboratory to locate the eggs. The procedure is quite routine in IVF clinics and, importantly, does not cause one to reach menopause earlier.

9. Key Success Metrics

Clinics often cite:

• Clinical Pregnancy Rate: The rate at which pregnancies are confirmed by ultrasound.

• Live Birth Rate: Potentially the most important metric for many patients, as it measures the outcome of a successful, term birth. Sadly, even confirmed pregnancies may end in miscarriage, so the live birth rate is often regarded as the definitive measure of success.

10. Embryo Transfer Limits

In certain countries, including the UK, regulations typically limit the number of embryos transferred to reduce the risk of multiple births. In many cases, up to two embryos can be transferred, though in special circumstances, clinics may transfer up to three. Policies vary by region and individual clinical assessments.

11. AMH Levels and Other Tests

AMH (Anti-Müllerian Hormone): This blood test gives an indication of your ovarian reserve (how many eggs might be retrieved). A higher AMH suggests a larger possible egg yield from stimulation, whereas a low AMH indicates a lower egg count potential.

Other Tests: You’ll likely undergo hormonal profiling, baseline ultrasounds and possibly genetic screening. These help create a tailored treatment plan.

12. Practical Timelines and Appointments

Freezing eggs usually involves four to five appointments. The schedule can be quite flexible except for the actual egg retrieval day, which is time-sensitive. Blood tests and ultrasounds guide the best moment for the retrieval. Often, blood must be taken and analysed by early afternoon (e.g., before 1 p.m.) so that hormone levels can direct the timing of ovulation induction. After retrieval, you can return to normal activities fairly quickly, though some rest is recommended.

13. Transporting Eggs, Sperm or Embryos

Moving Genetic Material: If needed, sperm or eggs (and sometimes embryos) can be transported between licensed clinics. In the UK, these must meet regulatory standards (“UK compliant”).

Cryogenic Logistics: Specialist courier services use liquid nitrogen containers to keep the temperature stable, ensuring no damage to the biological material during transit.

14. Physical and Emotional Preparation

Many professionals suggest allowing about two months to optimise your body before egg retrieval. This period typically includes:

• Reducing or eliminating alcohol.

• Managing stress levels.

• Improving sleep patterns.

A calmer, healthier state may improve hormonal responses and egg quality. The retrieval or transfer procedures themselves can sometimes cause bloating, fluid retention and other mild side effects, and you’ll usually be sedated for comfort.

15. Changing Reasons for Egg Freezing

Whereas fertility preservation was once almost exclusively for individuals with serious conditions (like cancer), increasing numbers of single parents or couples now choose egg freezing for personal reasons, including the desire for “reproductive autonomy.” As social and professional circumstances evolve, the freedom to plan or delay parenthood is a compelling motive for many.

16. Medication Protocols

“Using the right medication at the right time” is the fundamental principle of controlled ovarian stimulation for egg retrieval. Follicle-stimulating hormones (FSH) and other drugs aim to help multiple eggs mature simultaneously. The dosage and duration can vary significantly from person to person.

17. Screening and Costs

Embryo Health Checks: After fertilisation (be it through IVF or ICSI), many clinics offer genetic screening of embryos. This can cost around £250 or more, depending on the tests involved.

PGT-A and PGT-M:

• PGT-A (Preimplantation Genetic Testing for Aneuploidies) checks whether the embryo has the correct number of chromosomes, increasing the chances of a successful implantation.

• PGT-M is a test for monogenic (single-gene) disorders—useful if there is a known family history of a specific genetic condition.

18. Donor Matching and Surrogacy

If using donor eggs or sperm, the matching process is crucial. Donors may come from diverse ethnic backgrounds to suit the recipient’s needs. If the intended parent is above 45 or has medical concerns, a thorough health examination is standard to determine suitability for pregnancy. Should they be deemed medically unfit, a surrogate might be recommended.

19. Menopause and Egg Retrieval

A common misconception is that collecting eggs hastens menopause. In reality, egg retrieval does not affect the timing of menopause. Your body recruits a group of follicles (potential eggs) each cycle anyway, most of which would naturally disintegrate. Egg retrieval simply takes advantage of this monthly group.

20. Inclusivity of Different Ethnicities

Finally, fertility clinics in many regions can cater to recipients and donors from all ethnic backgrounds. Having a range of donors helps recipients find the closest possible match or align with their cultural or familial preferences.