Egg freezing: preserving fertility for future

Kind Fertility
Jan 29
3 min read

Egg freezing (oocyte cryopreservation) is an advanced assisted reproductive technology (ART) that enables individuals to preserve their fertility by storing mature oocytes for future use. This technique is particularly beneficial for those postponing pregnancy due to career, medical treatments like chemotherapy, or age-related fertility decline. Below is a detailed scientific exploration of the egg freezing process, optimal age for preservation, hormonal interventions, and associated risks.

Optimal age for egg freezing

The ovarian reserve, determined by the quantity and quality of oocytes, declines significantly with age due to increased meiotic errors and oxidative stress. Studies suggest that the ideal age range for egg freezing is between 25 and 35 years, as oocytes retrieved during this period exhibit higher euploidy rates and post-thaw viability. While cryopreservation can be performed at later ages, diminished ovarian reserve and increased aneuploidy rates reduce the probability of successful fertilization and implantation.

Egg freezing process: step-by-step breakdown

Baseline ovarian assessment – A comprehensive evaluation including serum Anti-Müllerian Hormone (AMH) levels, antral follicle count (AFC) via transvaginal ultrasound, and baseline Follicle-Stimulating Hormone (FSH) levels.
Controlled ovarian hyperstimulation (COH) – Exogenous gonadotropins stimulate multiple follicle development.
Follicular monitoring – Serial ultrasonographic and estradiol level assessments determine follicular response.
Ovulation triggering – Administration of human chorionic gonadotropin (hCG) or gonadotropin-releasing hormone (GnRH) agonist for final oocyte maturation.
Oocyte retrieval (oocyte aspiration) – Performed transvaginally under ultrasound guidance using a fine aspiration needle.
Cryopreservation (vitrification) – Mature oocytes are cryopreserved using rapid cooling with cryoprotectants to prevent ice crystal formation and cellular damage.

Medications and hormonal stimulation

Recombinant FSH (rFSH) and human menopausal gonadotropin (hMG) – Stimulate follicular growth.
GnRH antagonists (cetrorelix, ganirelix) – Suppress premature luteinizing hormone (LH) surges.
hCG or GnRH agonists – Facilitate final oocyte maturation before retrieval.

How many eggs should you freeze?

The probability of achieving a live birth correlates with the number of mature metaphase II (MII) oocytes retrieved. According to ART registries:

Women <35 years: 10–15 MII oocytes per intended pregnancy.
Women 35–40 years: 15–20 MII oocytes per pregnancy.
Women >40 years: A higher number of oocytes is necessary due to reduced implantation potential.

Time commitment and process duration

The egg-freezing process spans approximately 14–21 days, including:

1 week for ovarian assessment and protocol selection.
10–14 days of COH with daily hormone injections.
1-day transvaginal oocyte retrieval.
1–2 days for post-retrieval recovery.

Potential side effects and risks

Although egg freezing is generally safe, possible risks include:

Ovarian hyperstimulation syndrome (OHSS) – A rare but severe condition characterized by fluid accumulation and vascular permeability changes.
Injection site reactions – Mild erythema, bruising, or localized pain.
Hormonal side effects – Temporary mood swings, bloating, and fatigue.
Psychological impact – Emotional stress related to the process and outcomes.

Long-term considerations

Post-thaw survival rates – Vitrification achieves >90% oocyte survival rates.
Storage longevity – Cryopreserved eggs remain viable for decades without significant degradation.
Live birth rates – Depend on maternal age at retrieval, the number of frozen eggs, and embryo implantation conditions.
Success rates – Data indicate a 50–60% success rate per embryo transfer for younger women, decreasing with age.

Conclusion

Egg freezing is a revolutionary fertility preservation method that empowers individuals to take control of their reproductive choices. Understanding the scientific principles, procedural requirements, and long-term implications enhances informed decision-making. If you are considering egg freezing, consulting a reproductive endocrinologist can help determine the best approach based on your ovarian reserve, age, and reproductive goals.