Understanding the Basics of IVF

IVF is one of the most effective fertility treatments available, and millions of couples and individuals have turned to IVF to grow their families. However, the process can seem complex and overwhelming, especially for those just beginning to explore their fertility options. After all, there are many medications, appointments, and steps! This post will break down the basics of IVF to help you understand not only this process but future posts that build on this knowledge, such as IVF protocols, IVF add-ons, and a deep dive into mosaic embryo transfers.

What is IVF?

IVF, or in vitro fertilization, involves retrieving eggs and combining them with sperm in a lab. The resulting embryos are monitored and later transferred back into the uterus to attempt implantation and pregnancy. IVF is recommended for a variety of reasons, including tubal blockage, male factor infertility, unexplained infertility, endometriosis, ovulatory disorders, genetic disorders, uterine abnormalities, or after failure of other fertility treatments.

The IVF Process: Step-by-Step

In order to truly understand how IVF works, it’s essential to have a solid understanding of the menstrual cycle. So I highly encourage you to read my first blog post on that topic and return to this one afterward.

IVF typically involves five primary steps:

• Priming the ovaries (though this step is sometimes skipped)
• Stimulating the ovaries to grow multiple follicles to maximize the number of eggs retrieved (while avoiding hyperstimulation)
• Retrieving the eggs
• Fertilizing the eggs in the lab
• Culturing the embryos for 5-7 days

The embryo transfer is technically a separate procedure that occurs once usable embryos have been created. More on that later.

Priming

Priming suppresses the ovaries in hopes of keeping the follicles at similar sizes. The goal is to grow follicles in synchrony, which increases the number of eggs ready for retrieval. Priming commonly involves using birth control pills or estrogen. Additional strategies, such as using testosterone or growth hormone, can be employed for women with lower ovarian reserve to improve follicular response to stimulation.

Ovarian Stimulation

A standard IVF protocol involves using:

• Medications to stimulate follicle growth (follicle-stimulating hormone, or FSH)
• Medication to prevent premature ovulation, ensuring eggs aren’t lost before retrieval
• A “trigger” shot to mimic the body’s LH surge, maturing the eggs (only mature eggs can be fertilized)

Before ovarian stimulation begins, a baseline ultrasound is performed to check for any cysts or abnormal lab values that could affect treatment success. Once stimulation starts, you’ll have frequent monitoring appointments (about 2-3 times per week) to track follicle growth. Medication doses may be adjusted based on progress, and the trigger shot is timed when follicles reach about 20mm on average (though sizes may range from 15-26mm).

Egg Retrieval

During the egg retrieval procedure, a thin needle guided by ultrasound is used to aspirate the contents of each follicle. The follicular fluid is collected and handed off to the embryologist, who looks under the microscope and counts the eggs. Meanwhile, the partner’s sperm sample is collected (or previously frozen sperm is thawed). The sperm is processed in the lab to select the healthiest and most viable sperm for fertilization.

Fertilization

In the lab, eggs and sperm are combined through standard IVF or intracytoplasmic sperm injection (ICSI), a more advanced technique where a single sperm is directly injected into the egg to increase fertilization rates.

Embryo Development

The fertilized eggs are cultured in the lab for 5-7 days, during which they are closely monitored for growth and quality. In some cases, a biopsy of the outer cells of each embryo may be taken for preimplantation genetic testing (PGT) to screen for genetic abnormalities.

Embryo Transfer

Once embryos are created, we prepare the uterus for the transfer of one (or sometimes more) embryo. Typically, embryos are frozen and transferred in a later menstrual cycle, but in some cases, a fresh embryo transfer may be performed 3-5 days after egg retrieval. It’s important to note that frozen embryo transfers generally have higher success rates than fresh transfers.

What to Keep in Mind About IVF

It’s important to remember that IVF may not result in a successful pregnancy on the first attempt. Success rates vary depending on factors such as age, diagnosis, egg and sperm quality, and underlying medical conditions. Many individuals or couples may require multiple IVF cycles to achieve a live birth.