In vitro fertilization (IVF): A miracle of modern medicine

By Marta Wais MD | March 17, 2025

Understanding the IVF procedure

In vitro fertilization (IVF) stands as one of the most groundbreaking advancements in medical science, offering hope to countless individuals and families experiencing fertility challenges. Since its inception in the late 1970s, IVF has transformed from a controversial experiment to a sophisticated and widely embraced medical treatment. With over 10 million births attributed to IVF, it is a life-changing process for millions around the world.

This comprehensive article dives deep into the history, science, and modern practices of IVF, exploring its complexities, innovations, and the personal experiences tied to this journey.

To learn more about IVF, see IVF Part 2: Risks related to the egg producer, procedure, pregnancy & baby.

The Origins of IVF

The story of IVF is as remarkable as the procedure itself. It all began in England, culminating in 1978 with the birth of Louise Brown, the world’s first baby conceived through IVF. This monumental achievement was the work of Dr. Robert Edwards, Dr. Patrick Steptoe, and nurse embryologist Jean Purdy. Their dedication paved the way for a revolutionary treatment that would redefine reproductive medicine.

While Dr. Edwards received the Nobel Prize in Medicine in 2010 for his contributions, the significance of Jean Purdy’s role was long overlooked. Jean Purdy, the world’s first IVF nurse and embryologist, was instrumental in the process, even being the first to witness human egg fertilization in a lab. It wasn’t until 2018 that a memorial was unveiled to honor all three contributors.

Since the birth of Louise Brown, IVF has achieved widespread success. Each year, approximately 2.5 million IVF cycles are performed globally, resulting in 500,000 births annually. Over 10 million children have been born via IVF, a staggering testament to the evolution of this medical marvel.

The Evolution of IVF

When IVF first began, the process was rudimentary by today’s standards. There was no ovarian stimulation, and eggs were retrieved through laparoscopy. Advances in technology and understanding have since transformed IVF into a highly efficient and personalized treatment.

In modern IVF, the process is divided into four primary phases:

Stimulation Phase
Egg Retrieval
Fertilization and Embryo Culture
Embryo Transfer

Each phase is critical and tailored to the unique needs of the individual undergoing treatment.

1. Stimulation Phase: Preparing the Ovaries

The stimulation phase is designed to encourage the ovaries to produce multiple eggs rather than the one or two they would naturally release during a typical menstrual cycle. This is essential for maximizing the chances of successful fertilization and embryo development.

How It Works

Medications Used:
Controlled ovarian stimulation involves injectable medications known as gonadotropins, which stimulate the ovaries to develop multiple follicles. Simultaneously, antagonists or agonists are administered to prevent premature ovulation. This ensures that the follicles remain intact until they are ready for retrieval.
Monitoring:
During the stimulation phase, frequent monitoring is necessary. Blood tests measure hormone levels such as estrogen and luteinizing hormone (LH), while ultrasounds track the growth and size of the ovarian follicles.
Timing the Trigger:
Once the follicles reach the optimal size (typically between 17mm and 22mm), a “trigger shot” is administered. This injection induces the final maturation of the eggs, timed precisely to coincide with egg retrieval.

Length of Stimulation

Stimulation typically lasts 10–14 days, though this can vary depending on individual response. Regular clinic visits are required during this time to ensure the process is progressing as planned.

Common Experiences During Stimulation

Some individuals experience side effects during this phase, including bloating, mood swings, fatigue, or mild discomfort. These symptoms are generally manageable and temporary.

2. Egg Retrieval: The Pinnacle of the Process

Egg retrieval is the moment when all the preparation culminates. This minor surgical procedure involves collecting the eggs from the ovaries under sedation.

The Procedure

Conducted under ultrasound guidance, a thin needle is inserted through the vaginal wall to reach the ovaries. The eggs are gently aspirated from the follicles and collected in a lab.
The procedure typically takes 20–30 minutes, and patients can go home the same day, though they should refrain from driving or strenuous activities.

Sedation and Comfort

Egg retrieval is performed under sedation. At Markham Fertility Centre, anesthesiologists are present at each and every egg retrieval and they provide deep sedation with a medication called propofol, a powerful anesthetic. This ensures patient comfort and safety during the procedure.

What Happens Next?

After retrieval, the eggs are evaluated for maturity. Only mature eggs are viable for fertilization. On average, 70% of retrieved eggs will be mature.

3. Fertilization and Embryo Culture

Once the eggs are retrieved, the next step is to fertilize them with sperm in the laboratory. This can occur through two main methods:

Conventional IVF

In this method, an egg and tens of thousands of sperm are placed together in a Petri dish. Fertilization occurs more naturally when a sperm penetrates the egg.

Intracytoplasmic Sperm Injection (ICSI)

ICSI involves injecting a single sperm directly into the egg. This method is often used in cases of male infertility or unexplained infertility.

Monitoring Embryo Development

Embryos are cultured in the lab and monitored for several days. By day 3, they are typically composed of 6–8 cells. By day 5 or 6, they should reach the blastocyst stage, where they are ready for transfer, freezing or biopsy for genetic testing.

The Funnel Effect

Not all eggs retrieved will lead to viable embryos. Each stage sees a natural drop-off:

Not every follicle contains an egg.
Not every egg retrieved is mature.
Not every fertilized egg develops into a blastocyst.
Not every blastocyst will lead to a pregnancy

This “funnel effect” emphasizes the importance of retrieving multiple eggs to increase the likelihood of success.

4. Embryo Transfer: Completing the Cycle

The embryo transfer is the final step in the IVF process. This involves placing a carefully selected embryo into the uterus.

Fresh vs. Frozen Transfers

Fresh Transfers: Performed during the same cycle as egg retrieval. These transfers happen sooner but are less common today due to the risk of ovarian hyperstimulation syndrome (OHSS) and increasing interest in preimplantation genetic testing.
Frozen Transfers: More common due to advancements in embryo freezing (vitrification). Frozen embryos often yield higher success rates, particularly when combined with preimplantation genetic testing (PGT).

Timing and Technique

The transfer is typically performed on day 5 of embryo development. Rarely we may do a fresh embryo transfer on the third day of embryo development in specific cases. It is a quick and minimally invasive procedure, akin to a Pap Smear.

IVF: Challenges and Considerations

While IVF has brought joy to millions, it is not without its challenges. The process demands physical, emotional, and financial commitment.

Emotional Impact

The emotional rollercoaster of IVF is undeniable. The anticipation of each step, coupled with the uncertainty of outcomes, can be overwhelming. Support from family, friends, or counselors is invaluable during this journey.

Financial Considerations

IVF is a significant financial investment. Costs vary widely, depending on the country, clinic, and specific treatments involved. Patients often face additional expenses for medications, genetic testing, and embryo storage.

Physical Side Effects

While most side effects are mild, such as bloating or fatigue, some individuals may experience more significant symptoms. One rare but serious complication is ovarian hyperstimulation syndrome (OHSS), which requires careful management.

IVF: The Science Behind Success

The success of IVF depends on numerous factors, including:

Age: Younger individuals, specifically the egg provider, generally have higher success rates due to better egg quality.
Egg and Sperm Quality: Healthy gametes are crucial for successful fertilization and embryo development.
Embryo Grading: Embryos are graded based on their appearance and developmental progress, helping embryologists select the most promising ones for transfer.
Genetic Testing Results: Some individuals will opt to proceed with pre-implantation genetic testing and this can provide information regarding the genetics of the embryo and this can further predict success.

IVF: Fresh vs. Frozen Embryo Transfers: A Closer Look

The choice between fresh and frozen embryo transfers depends on individual circumstances.

Advantages of Fresh Transfers

Quicker time to pregnancy.
Reduced cost, as freezing and thawing are not required.

Advantages of Frozen Transfers

Higher success rates due to improved freezing techniques.
Allows for preimplantation genetic testing (PGT).
Safer for patients at risk of OHSS.

In vitro fertilization is nothing short of miraculous, offering hope where once there was none. From its historic beginnings to the advanced techniques used today, IVF continues to evolve, making parenthood possible for millions.

Though the journey can be challenging, the rewards are profound. By understanding the process, setting realistic expectations, and seeking support, individuals and couples can navigate this life-changing experience with confidence.

The miracle of IVF is a testament to human innovation, determination, and the unyielding desire to create new life. Whether you’re considering IVF or simply learning about it, the story of IVF is a powerful reminder of what modern medicine can achieve.

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