Understanding the Different Phases of IVF

A step-by-step timeline. In vitro fertilization (IVF) is one of the most advanced and widely used fertility treatments available today. While the process may seem overwhelming at first, breaking it down into distinct phases can make it easier to understand and prepare for. In this blog, we’ll...
In vitro fertilization (IVF) is one of the most advanced and widely used fertility treatments available today. While the process may seem overwhelming at first, breaking it down into distinct phases can make it easier to understand and prepare for. In this blog, we’ll walk through each stage of IVF, from preparation to embryo transfer—whether you opt for a fresh transfer or decide to freeze your embryos for later. Understanding these phases will help you navigate your IVF journey with clarity and confidence.
Phase 1: Ovarian Stimulation (Weeks 1-2)
The IVF process begins with ovarian stimulation, where medications are used to encourage the ovaries to produce multiple eggs instead of the single egg released during a natural cycle.
- Medications: You will be prescribed hormone injections, such as follicle-stimulating hormone (FSH) and luteinizing hormone (LH), to stimulate the ovaries. These medications are typically administered daily for 8-14 days.
- Monitoring: During this phase, regular ultrasounds and blood tests are done to monitor how your ovaries are responding to the medication. The goal is to track the growth of multiple follicles, which contain the eggs.
- Trigger Shot: Once the follicles have matured (usually around 18-20 mm in size), you’ll be given a "trigger shot" of human chorionic gonadotropin (hCG) to induce ovulation. This injection helps the eggs fully mature and prepares them for retrieval.
Phase 2: Egg Retrieval (Day 14-16)
Around 36 hours after the trigger shot, you will undergo egg retrieval—a minor surgical procedure to collect the eggs from your ovaries.
- Procedure: The egg retrieval is typically done under sedation. Using an ultrasound-guided needle, the fertility specialist will retrieve the eggs from the follicles through the vaginal wall.
- Recovery: The procedure takes about 20-30 minutes, and you’ll be able to go home after a short recovery period. Some mild cramping and spotting afterward is normal.
Phase 3: Sperm Collection and Fertilization (Day 15-17)
On the same day as the egg retrieval, a sperm sample from your partner (or a sperm donor) is collected.
- Sperm Collection: If using a partner’s sperm, the sample can either be provided on the day of retrieval or frozen ahead of time. If using donor sperm, it is thawed and prepared.
- Fertilization: Once the eggs and sperm are ready, the fertilization process takes place. There are two methods:
- Traditional IVF: The eggs and sperm are combined in a petri dish, where the sperm naturally fertilizes the egg.
- Intracytoplasmic Sperm Injection (ICSI): In cases of male factor infertility or previous fertilization issues, a single sperm is injected directly into each egg.
Phase 4: Embryo Development (Day 17-21)
After fertilization, the embryos begin to develop and grow. The clinic monitors the embryos closely over the next 3-5 days.
- Day 1-3: During the first three days, the fertilized eggs divide into cells, growing from 2 to 8 cells.
- Day 5: By day 5, the healthiest embryos typically reach the blastocyst stage, where the embryo has developed more complex structures. Blastocysts have a higher chance of implantation.
If You’re Doing a Fresh Embryo Transfer:Phase 5a: Fresh Embryo Transfer (Day 19-23)
For patients opting for a fresh embryo transfer, the process continues soon after the embryos reach the blastocyst stage.
- Procedure: The embryo transfer is a quick and simple procedure. Using a thin, flexible catheter, the selected embryo(s) are placed directly into the uterus.
- Number of Embryos: Your fertility specialist will recommend the number of embryos to transfer based on your age, health, and personal preferences.
- Rest Period: After the transfer, you'll rest briefly before resuming daily activities. The next few days are critical as the embryo attempts to implant in the uterine lining.
Phase 6: The Two-Week Wait (Day 24-38)
After a fresh embryo transfer, you’ll begin the two-week wait—a period of anticipation before taking a pregnancy test.
- Progesterone Support: To support implantation and early pregnancy, you'll likely be given progesterone supplements.
- Rest and Patience: Avoid strenuous activity and focus on self-care. The waiting period can be emotionally challenging, so support from loved ones or counseling can be helpful.
If You’re Freezing Your Embryos for a Later Transfer:Phase 5b: Embryo Freezing (Day 19-21)
In some cases, you might choose or be advised to freeze your embryos instead of proceeding with a fresh transfer. Common reasons for freezing embryos include:
- Medical Reasons: If your hormone levels are too high after stimulation (risk of ovarian hyperstimulation syndrome), or you need more time to recover, a frozen transfer might be safer.
- Elective Freezing: Some patients choose to freeze embryos to delay pregnancy, allowing them to focus on personal or professional goals.
- Genetic Testing: Freezing the embryos allows time for pre-implantation genetic testing (PGT) to identify any chromosomal abnormalities.
- Process: The embryos are carefully frozen using a process called vitrification, which protects them from damage and allows them to be stored for years.
Preparing for a Frozen Embryo Transfer (FET) (Weeks to Months Later)
When you’re ready for a frozen embryo transfer (FET), your body will be prepared to receive the embryo:
- Endometrial Preparation: You’ll take estrogen and progesterone to thicken the uterine lining, ensuring it’s ready for implantation. Monitoring will continue with blood tests and ultrasounds to ensure the uterus is in optimal condition.
- FET Procedure: Similar to a fresh transfer, the frozen embryo is thawed and transferred to the uterus via a thin catheter. The procedure is quick and painless.
- Rest and Care: As with fresh transfers, you’ll rest after the procedure, with the same two-week waiting period before taking a pregnancy test.
Phase 6: The Two-Week Wait (After FET)
Even with a frozen transfer, the waiting game is the same. Two weeks after the procedure, you’ll take a pregnancy test to determine if the embryo has successfully implanted.Phase 7: Pregnancy Test (Day 38-42)
Two weeks after the embryo transfer—whether fresh or frozen—a blood test will determine if you’re pregnant.
- Blood Test: Your fertility clinic will measure hCG levels to confirm pregnancy.
- Next Steps: If the test is positive, additional blood tests and ultrasounds will follow to monitor the early stages of pregnancy. If the test is negative, your fertility specialist will help you determine the next steps, such as another IVF cycle or frozen embryo transfer.
Phase 1: Ovarian Stimulation (Weeks 1-2)
The IVF process begins with ovarian stimulation, where medications are used to encourage the ovaries to produce multiple eggs instead of the single egg released during a natural cycle.
- Medications: You will be prescribed hormone injections, such as follicle-stimulating hormone (FSH) and luteinizing hormone (LH), to stimulate the ovaries. These medications are typically administered daily for 8-14 days.
- Monitoring: During this phase, regular ultrasounds and blood tests are done to monitor how your ovaries are responding to the medication. The goal is to track the growth of multiple follicles, which contain the eggs.
- Trigger Shot: Once the follicles have matured (usually around 18-20 mm in size), you’ll be given a "trigger shot" of human chorionic gonadotropin (hCG) to induce ovulation. This injection helps the eggs fully mature and prepares them for retrieval.
Phase 2: Egg Retrieval (Day 14-16)
Around 36 hours after the trigger shot, you will undergo egg retrieval—a minor surgical procedure to collect the eggs from your ovaries.
- Procedure: The egg retrieval is typically done under sedation. Using an ultrasound-guided needle, the fertility specialist will retrieve the eggs from the follicles through the vaginal wall.
- Recovery: The procedure takes about 20-30 minutes, and you’ll be able to go home after a short recovery period. Some mild cramping and spotting afterward is normal.
Phase 3: Sperm Collection and Fertilization (Day 15-17)
On the same day as the egg retrieval, a sperm sample from your partner (or a sperm donor) is collected.
- Sperm Collection: If using a partner’s sperm, the sample can either be provided on the day of retrieval or frozen ahead of time. If using donor sperm, it is thawed and prepared.
- Fertilization: Once the eggs and sperm are ready, the fertilization process takes place. There are two methods:
- Traditional IVF: The eggs and sperm are combined in a petri dish, where the sperm naturally fertilizes the egg.
- Intracytoplasmic Sperm Injection (ICSI): In cases of male factor infertility or previous fertilization issues, a single sperm is injected directly into each egg.
Phase 4: Embryo Development (Day 17-21)
After fertilization, the embryos begin to develop and grow. The clinic monitors the embryos closely over the next 3-5 days.
- Day 1-3: During the first three days, the fertilized eggs divide into cells, growing from 2 to 8 cells.
- Day 5: By day 5, the healthiest embryos typically reach the blastocyst stage, where the embryo has developed more complex structures. Blastocysts have a higher chance of implantation.
If You’re Doing a Fresh Embryo Transfer:Phase 5a: Fresh Embryo Transfer (Day 19-23)
For patients opting for a fresh embryo transfer, the process continues soon after the embryos reach the blastocyst stage.
- Procedure: The embryo transfer is a quick and simple procedure. Using a thin, flexible catheter, the selected embryo(s) are placed directly into the uterus.
- Number of Embryos: Your fertility specialist will recommend the number of embryos to transfer based on your age, health, and personal preferences.
- Rest Period: After the transfer, you'll rest briefly before resuming daily activities. The next few days are critical as the embryo attempts to implant in the uterine lining.
Phase 6: The Two-Week Wait (Day 24-38)
After a fresh embryo transfer, you’ll begin the two-week wait—a period of anticipation before taking a pregnancy test.
- Progesterone Support: To support implantation and early pregnancy, you'll likely be given progesterone supplements.
- Rest and Patience: Avoid strenuous activity and focus on self-care. The waiting period can be emotionally challenging, so support from loved ones or counseling can be helpful.
If You’re Freezing Your Embryos for a Later Transfer:Phase 5b: Embryo Freezing (Day 19-21)
In some cases, you might choose or be advised to freeze your embryos instead of proceeding with a fresh transfer. Common reasons for freezing embryos include:
- Medical Reasons: If your hormone levels are too high after stimulation (risk of ovarian hyperstimulation syndrome), or you need more time to recover, a frozen transfer might be safer.
- Elective Freezing: Some patients choose to freeze embryos to delay pregnancy, allowing them to focus on personal or professional goals.
- Genetic Testing: Freezing the embryos allows time for pre-implantation genetic testing (PGT) to identify any chromosomal abnormalities.
- Process: The embryos are carefully frozen using a process called vitrification, which protects them from damage and allows them to be stored for years.
Preparing for a Frozen Embryo Transfer (FET) (Weeks to Months Later)
When you’re ready for a frozen embryo transfer (FET), your body will be prepared to receive the embryo:
- Endometrial Preparation: You’ll take estrogen and progesterone to thicken the uterine lining, ensuring it’s ready for implantation. Monitoring will continue with blood tests and ultrasounds to ensure the uterus is in optimal condition.
- FET Procedure: Similar to a fresh transfer, the frozen embryo is thawed and transferred to the uterus via a thin catheter. The procedure is quick and painless.
- Rest and Care: As with fresh transfers, you’ll rest after the procedure, with the same two-week waiting period before taking a pregnancy test.
Phase 6: The Two-Week Wait (After FET)
Even with a frozen transfer, the waiting game is the same. Two weeks after the procedure, you’ll take a pregnancy test to determine if the embryo has successfully implanted.Phase 7: Pregnancy Test (Day 38-42)
Two weeks after the embryo transfer—whether fresh or frozen—a blood test will determine if you’re pregnant.
- Blood Test: Your fertility clinic will measure hCG levels to confirm pregnancy.
- Next Steps: If the test is positive, additional blood tests and ultrasounds will follow to monitor the early stages of pregnancy. If the test is negative, your fertility specialist will help you determine the next steps, such as another IVF cycle or frozen embryo transfer.