From Oogenesis to Oocyte Cryopreservation: Understanding Fertility Preservation

From the earliest stages of life, a female’s reproductive journey begins long before birth. Inside the ovaries of a developing fetus, a small population of germ cells called oogonia multiply rapidly. By five to seven months of gestation, their numbers peak at nearly 6–7 million.

As the fetus develops further, most of these cells naturally degenerate. By birth, only 1–2 million oocytes remain. These surviving cells, now called primary oocytes, have already started the first stage of meiosis, but they pause at prophase I, remaining dormant for years.

Even during childhood, oocytes continue to decline. By puberty (12–13 years), roughly 300,000–400,000 remain. During the reproductive years, only a small number of these oocytes mature each month, with usually one ovulated, while the rest degenerate. Across an entire reproductive lifetime, only about 400-500 oocytes will ever mature and be released. The rest gradually fade away through a natural process known as atresia.

As the years pass, the reserve of oocytes steadily declines :

Who should consider egg freezing?

The egg cell, or oocyte, is the largest cell in the human body, measuring about 110 micrometers in diameter. It carries everything needed to begin a new life once it is fertilized by a sperm. Oocyte cryopreservation, commonly known as egg freezing, was initially introduced as a fertility-preservation option for women undergoing cancer treatment. Over time, its application has expanded beyond oncology to include social and other medical reasons for fertility preservation. Today, egg freezing is widely recognized as a method that can help extend a woman’s reproductive potential. Egg freezing can be categorised into two categories depending on the purpose of freezing:

Medical egg freezing

Fertility preservation for cancer patients

Women undergoing treatments that may damage ovarian function

Social egg freezing

Women choosing to delay pregnancy for career, personal, or relationship reasons

Over the past few decades, the way women plan their lives has changed significantly. Many women today pursue higher education, build careers, travel, and explore personal goals before starting a family. While the desire to have children often remains strong, the timing of motherhood is frequently delayed due to professional aspirations, personal circumstances, or waiting to find the right partner.

However, the biggest challenge with delaying pregnancy is biology. Women are born with a fixed number of eggs, and both the quantity and quality of these eggs decline with age. As time passes, the chances of natural conception decrease and the risk of chromosomal abnormalities in eggs increases.

This is where egg freezing / oocyte cryopreservation has become a powerful option.

Advances in reproductive science, especially the development of vitrification (rapid freezing techniques), have greatly improved the success rates of egg freezing. Today, frozen eggs can survive the thawing process with high success, making this technology an important tool for women who want greater flexibility in planning their future families.

The first birth from frozen eggs was reported in 1986 by Dr. Christopher Chen in Australia.

Egg freezing in India:

In India, egg freezing is legally permitted under the ART Act 2021, which regulates fertility clinics, ensures ethical use of reproductive cells, limits donor practices, and allows eggs to be stored for up to 10 years in licensed ART banks.

Common patient concerns during egg freezing:

At what age should I freeze my eggs?

• The ideal age is before 35, when egg quality and quantity are highest. Freezing after 35 is possible, but success rates decline as eggs are fewer and less healthy.
• According to the ART Bill 2021, women  between 21-50 years are eligible for egg freezing for self cycles and women between the age of 23-35 years can donate eggs (oocytes). (Section 27(2) (a) & 2 (b) of ART Act,2021).
• Also, single women may avail ART services. (ART Bill, 2021)

Does my ovarian reserve matter?

• Yes. Tests like AMH (Anti-Mullerian Hormone) and antral follicle count indicate your ovarian reserve and help estimate how many eggs can be collected.

How does the egg freezing process work?

• It involves three main steps:

1. Ovarian stimulation using hormones to produce multiple eggs.
2. Egg retrieval via a minor procedure under sedation.
3. Vitrification (rapid freezing) for long-term storage.

What are the chances of future pregnancy using frozen eggs?

• It depends on age at freezing, number of eggs, and fertility factors. Women who freeze eggs before 35 have higher success rates than those who freeze later.

Does freezing eggs guarantee a baby?

• No. Egg freezing increases the chance of pregnancy later, but success is not guaranteed.

How does age at freezing affect success rates?

• Younger eggs (20s to early 30s) are healthier and more likely to form an embryo, implant, and result in a successful pregnancy.

How long can eggs be safely stored?

• The eggs /gametes can be stored for up to 10 years.
• ART clinics shall allow cryopreservation of oocytes, for oncofertility patients undergoing treatment and for other such conditions, for duration longer than 10 years with permission from the National board.

How much does one egg freezing cycle cost in India?

• On average ₹1.5–3.5 lakhs per cycle, depending on the clinic and city.

What are annual storage charges?

• Typically ₹20,000–₹50,000 per year depending on the number of straws or gametes vitrified.

Can frozen eggs be donated or used for research?

• Donation is allowed if the patient consents. Research use is possible only under strict legal and ethical regulations.
• Female egg donors should be between 23-35 years of age, with at least one child (minimum 3 years old). Throughout their lifetime only one donation for an egg donor can be made with up to 7 eggs retrieved. (Section 27 (4) of ART Act, 2021)

Are there any consent forms?

• Yes. Indian clinics follow ART regulations, and must provide written informed consent for egg freezing, storage, and potential future use.

Can egg freezing be combined with IVF later?

• Yes.Frozen eggs can be thawed and fertilized via IVF/ICSI whenever the couple are ready. 

Which technology is used for egg freezing?

• Most top clinics use vitrification, a rapid freezing technique that preserves egg quality efficiently.

Discover egg freezing trends in India:

Egg freezing is no longer a niche procedure, it’s becoming a common choice for women across India. In the last year alone, interest has soared by over 150%, with Delhi, Mumbai, and Bengaluru leading the way. Metro cities like Hyderabad, Pune, and Delhi‑NCR are seeing the biggest spikes, but awareness is spreading steadily to Tier‑2 cities including Ahmedabad, Chandigarh, Kochi, Indore, and Lucknow.

For many women, egg freezing is more than a medical procedure, it’s a way to take control of their reproductive future. Often called “fertility insurance,” it allows women to plan pregnancies on their own timeline, balancing personal ambitions, career goals, and family planning.
Experts note that with India’s fertility rate at 1.9 children per woman, below the replacement level of 2.1, services like egg freezing could play an important role in helping women balance personal, professional, and family planning goals while also contributing to broader reproductive and demographic planning.

References:

1. Ghumman, S. S. (2012). Step by Step® Protocols in Clinical Embryology and ART. India: Jaypee Brothers Medical Publishers.
2. Gilbert SF. Developmental Biology. 6th edition. Sunderland (MA): Sinauer Associates; 2000. Oogenesis. Available from: https://www.ncbi.nlm.nih.gov/books/NBK10008/
3. Gook D. A. (2011). History of oocyte cryopreservation. Reproductive biomedicine online, 23(3), 281–289. https://doi.org/10.1016/j.rbmo.2010.10.018.
4. ART Regulations Bill (2021)

About the Writer:

Sindhoora Rao B is an Application Specialist – IVF Division at DSS Imagetech, with professional experience in embryology and assisted reproductive technologies. She works closely with leading IVF clinics across India, supporting the implementation and effective use of advanced laboratory technologies to enhance embryo assessment and optimize clinical outcomes. Her expertise includes embryology laboratory workflows, embryo culture systems, time-lapse imaging technologies, and AI-based embryo assessment platforms. She also has strong experience in application support, technical training, troubleshooting, and helping clinics integrate new technologies seamlessly into their routine IVF practices.