In vitro fertilization, more commonly known as IVF, is a medical treatment involving the retrieval of mature eggs from a woman’s ovaries and the fertilization of those eggs with sperm in a laboratory dish.

What is IVF?

In vitro fertilization, more commonly known as IVF, is a medical treatment involving the retrieval of eggs from the ovaries and the fertilization of those eggs with sperm in a laboratory dish. The fertilized egg (now an embryo) can then be transferred to a woman’s uterus for development.

IVF is currently one of the most effective forms of assisted reproductive technology (ART). It can be done using one’s own genetic material (egg or sperm) or from a donor.  Donors can be identified or unidentified. Sometimes another person’s uterus is used.


Benefits of IVF:

  • Fallopian tubes are not needed for IVF. If a person’s fallopian tubes are blocked or damaged due to a previous pelvic infection, endometriosis, or surgical scarring, IVF is the only possible treatment for conception. IVF does not require the use of fallopian tubes. Eggs are retrieved from the ovaries and fertilized outside the body. The developing embryo is then implanted directly into the uterus.
  • Low sperm count can be addressed with IVF. If the quality or quantity of a partner’s sperm is an issue, timed intercourse or IUI may not be a suitable option in many cases. Sperm may have trouble reaching the eggs. With IVF, sperm are either placed on the egg or injected directly into the eggs by Intracytoplasmic Sperm Injection (ICSI), making successful fertilization much more likely.
  • Lowered chances of embryo abnormalities. For patients at risk for embryo abnormalities, IVF makes chromosome and genetic testing possible with preimplantation testing (PGT). This testing reduces the risk of passing along a genetic or hereditary disease. It also reduces the risk of miscarriage from transferring a genetically abnormal embryo.

When is IVF recommended for a fertility patient?

IVF is often recommended for patients who have fertility challenges such as:

  • Fallopian tube damage or blockages
  • Sperm quality or sperm quantity problems
  • Disorders that affect ovulation such as polycystic ovary syndrome (PCOS)
  • Endometriosis
  • Uterine fibroids
  • Pelvic infection
  • Surgical scarring
  • Diminished egg quality
  • Age-related fertility problems

    IVF treatment may also be recommended to patients who want to:

    • Store embryos for future pregnancies
    • Have concerns about genetic diseases
    • Will be undergoing cancer therapy or other gonadotoxic treatment

    How does IVF work?

    Step 1: Ovarian stimulation

    Understanding hormones and starting ovarian stimulation

    When a person starts a typical menstrual cycle, the pituitary gland (in the brain) releases Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH). These hormones cause the ovary to select a single follicle to grow.

    Diagram of What Actually Happens During Hyper-stimulation of the Ovaries

    To begin stimulation of the ovaries, a fertility patient takes injections containing synthetic or purified forms of FSH and LH (also called gonadotropins) for 8-12 days. These injections are given every day just below the skin. As the patient continues to take injections, multiple follicles will grow, making more reproductive hormones (mainly estrogen and a small amount of progesterone).

    The fertility specialists will monitor hormone levels and follicle sizes closely until the largest follicles (called the lead follicles) reach a size of about 18-22 mm.

    At this point, the fertility specialist will determine the best time for the patient to take the final medication (called the “trigger shot”) to help the eggs in the follicles reach maturity and be available for retrieval.

    What is an IVF trigger shot?

    When ovarian stimulation is complete and follicles have reached their ideal sizes, a self-injection will trigger egg release. Most patients release eggs from their follicles after their trigger shot. Egg retrievals, therefore, occur 35-36 hours after the trigger shot.

    Step 2: Egg retrieval

    Prior to egg retrieval, an anesthesiologist will administer medications to keep the patient comfortable. Typically, egg retrieval is associated with minimal discomfort. During egg retrieval, a small needle is guided through a channel at the end of an ultrasound probe. With the guidance of ultrasound, the tip of the needle is placed through the vagina and into each individual follicle in the ovary. Fluid taken from each follicle will be examined by embryologists to confirm that an egg(s) is present. The entire procedure usually takes about 20 minutes.

    Step 3: Egg fertilization

    There are two methods used for fertilizing eggs with the IVF process:

    • Conventional insemination. With conventional insemination, 25,000-50,000 sperm are combined with individual eggs in the lab.
    • Intracytoplasmic sperm injection (ICSI). With ICSI, only a single sperm is combined with an individual egg.

    With ICSI, an embryologist selects individual sperm under the microscope with a regular shape and robust motility (movement).

    Then, with a very small and specially designed glass needle, the embryologist will inject just a single sperm into each mature egg for fertilization. Approximately 18-24 hours after the egg and sperm come together, the genetic material of both females and males combine to form a fertilized egg (a zygote).

    On average, about 70-90% of mature eggs are fertilized with IVF.

    What Happens During Egg Retrieval?
    IVF - What Happens to the Eggs?

    Step 4: Embryo incubation

    Once fertilized in the lab, an embryo is placed in an incubator to simulate the fallopian tubes and the uterus’ temperature, oxygen, carbon dioxide, and nutrient levels. The embryo will grow and develop as if it were inside a person’s body. The cells will grow and divide (cleavage) daily.

    • 1 day after egg retrieval and fertilization, the embryo (pronuclear) is one cell.
    • 2 days after egg retrieval, the embryo comprises four cells.
    • 3 days after egg retrieval, the embryo is made up of eight cells
    • 5 days after egg retrieval, the embryo has grown significantly and has divided into a collection of hundreds of cells. The embryo is now at an advanced stage called a blastocyst.

    Embryos will be biopsied and/or frozen on day 5. Extra embryos can remain frozen for years for future use.

    IVF - embryo incubation at Lane Fertility Institute

    Step 5: Embryo Biopsy and Preimplantation Genetic Testing (PGT)

    Pre-implantation genetic testing for aneuploidy (PGT-A). As individuals age, a higher percentage of their embryos are genetically abnormal. This higher rate of genetically abnormal embryos (aneuploidy) is the greatest contributing factor to an increased chance of unsuccessful IVF cycles and recurrent miscarriages in older women.

    Therefore, the most common reason that PGT-A is used with IVF is to prevent the transfer of genetically abnormal embryos that can result in non-pregnancies, miscarriages, or genetic abnormalities such as Down’s Syndrome.

    During PGT-A, embryo biopsies are performed on embryos created via IVF to diagnose abnormal chromosomes or a genetic disorder before implantation in the uterus. PGT is performed when embryos reach the blastocyst stage. 

    Preimplantation genetic testing for monogenic/single gene defects (PGT-M). This genetic testing is performed on an IVF embryo prior to its transfer to identify any presence of a specific gene mutation. It is a very helpful test for those who may be carriers of a genetic disease. By avoiding the transfer of embryos affected with a genetic disease, patients can ensure that babies resulting from IVF will be free of the inheritable disease.

    PGT-M is often done when a couple has a medical history of chromosome anomalies, recessive genes, or serious health complications.

    Several cells are taken from the embryo during the embryo biopsy. The embryo is then frozen (vitrification) for later thaw and transfer when testing on the cells is completed.

    ivf - embryo biopsy at Lane Fertility Institute

    Embryo selection

    Fertility specialists use a standardized system to identify which embryos are of good quality (this is called grading). With this system, the best quality embryo(s) can be selected for frozen transfer.

    While gender is documented with embryo biopsy results, sometimes selecting a particular gender for transfer may not align with the best quality embryo available for transfer.

    IVF - Embryo Grading & Success Rates

    Step 6: Embryo Transfer

    How many embryos will be transferred to the uterus?

    In most cases, fertility specialists recommend the transfer of just a single embryo. This is particularly true if the identified embryo is known to be genetically normal. In some cases, however, the number of embryos transferred to the uterus depends upon a patient’s age and clinical situation.

    What happens during the transfer procedure?

    No sedation or pain medication is required for the transfer procedure. Many practices will use a mild sedative to relax the uterus. Most patients say the level of discomfort involved in an embryo transfer is equivalent to having a routine gynecologic examination like a PAP smear or intrauterine insemination (IUI).

    The embryo(s) (either fresh or thawed) will be loaded into a specialized embryo transfer catheter and placed through the external opening of the cervix. The tip of the catheter will then be placed in the uterine lining.

    Hormonal support for an embryo transfer

    Many fertility patients take hormonal medications (progesterone and estrogen) to help the lining of the uterus:

    • Become receptive to the transferred embryo
    • Optimize the success of the embryo implanting in the lining of the uterus
    • Support the growth of an early pregnancy
    Embryo Transfer

    Step 7: Pregnancy Testing

    If an embryo(s) successfully implants into the lining of the uterus, it will release the pregnancy hormone, human chorionic gonadotropin (hCG). This can be detected by a blood test or by a urine test (such as over-the-counter home pregnancy tests).

    Typically, an hCG blood test will be drawn 10-12 days after a blastocyst embryo transfer to determine if pregnancy has been achieved. If pregnancy has not been achieved during this cycle, a transfer can be repeated with another thawed embryo. If the patient does not have remaining embryos than they must undergo another egg retrieval first.

    If the embryo has implanted successfully, hCG will be positive and detected at a specific numerical level. If the hCG test is positive, a second blood hCG level will be checked 48 hrs later to confirm that the level is continuing to rise appropriately.

    pregnancy test

    Pregnancy Ultrasound(s)

    If hCG levels rise appropriately, a patient will be scheduled for their first pregnancy ultrasound approximately 2 weeks from their blood testing. The ultrasound is done to confirm that the pregnancy is growing in the correct location in the uterus and the number of pregnancies (for example singleton vs twins). Once everything is confirmed as normal, the patient will then be referred to their obstetrician for prenatal care.

    Pregnancy Ultrasound(s)

    What are the variables for success with IVF?

    The potential success of having a baby using IVF depends on several factors, including: 

    • Cause of infertility
    • Maternal age and reproductive history
    • Medical surgeries in the past
    • Genetic and lifestyle factors
    • Sperm quality
    • Uterine quality

    The Centers for Disease Control (CDC) has developed a calculating tool that estimates an individual’s or couple’s chance of having a baby using in vitro fertilization (IVF).

    These estimates are based on the data the CDC has available and may not be representative of anyone’s unique circumstances.


    It is also important to note the CDC success estimator tool does not provide any medical advice, diagnosis, or treatment. Intended parents should talk to a fertility specialist about their own specific treatment plan and potential for success.

    Here at LFI, we know that fertility treatment can be a complex and multi-faceted process. Do not hesitate to call our team with any questions you have before, during, and after your treatment.