How IVF Works: A Guide to the Stages of in Vitro Fertilization

In vitro fertilization (IVF) an advanced treatment for infertility. While it may sound complicated, the process can be broken down into a series of steps that work together to help create a healthy pregnancy, according to Stacia Woodcock, PharmD, Pharmacy Editor at GoodRx.

Stage 1: Stimulating Egg Maturity

The first step is stimulation. Medications are used to encourage the ovaries to produce multiple healthy eggs. Normally, the body releases only one egg per cycle, but IVF medications prompt the ovaries to mature several eggs during a single cycle.

Stage 2: Preventing Egg Release

IVF medications also keep the body from releasing mature eggs too soon. This allows for careful timing and control of the egg retrieval process.

Stage 3: Triggering Egg Release

Once the eggs mature, doctors give a “trigger” shot. This is a medication that signals the ovaries to release the mature eggs from follicles at a predictable time. 

Stage 4: Egg Retrieval

Egg retrieval happens about 24 hours after you receive the trigger shot. Egg retrieval is a minor surgical procedure that requires anesthesia. A reproductive endocrinologist uses ultrasound to direct a hollow needle through the vaginal wall and into the ovaries. They use the needle to aspirate the mature eggs out of the follicles. The eggs are then placed into a petri dish and checked to make sure they are mature and can be fertilized. 

Stage 5: Fertilization

Now comes the “in vitro” part: fertilization outside the body. Sperm is added to the retrieved eggs by an embryologist. Embryos develop if sperm is able to fertilize the eggs. Over 3 to 5 days, the embryologist monitors as early embryos, called blastocysts, develop. Healthy embryos can then be transferred or sent for genetic testing, if needed.

Stage 6: Embryo Transfer

The final step is the embryo transfer. This can happen in two ways: a fresh transfer, where embryos are implanted within three to five days after egg retrieval and fertilization, or a frozen transfer, where an embryo that was previously created and stored for use later is implanted. 

A reproductive endocrinologist uses a catheter (small tube) to transfer the embryos from the petri dish into the uterus. Once transferred, the embryos hopefully implant and develop into a pregnancy, just as they would naturally.

Though IVF is a complex process, understanding these steps can make it feel less overwhelming. Each stage is carefully designed to give people the best possible chance of success on their fertility journey.