What is In Vitro Fertilization? Understanding IVF, Process, and Success Rates

In vitro fertilization (IVF) is a beacon of hope for individuals and couples grappling with infertility. This assisted reproductive technology (ART) offers a pathway to pregnancy when natural conception proves challenging. IVF is a complex yet highly effective series of procedures designed to fertilize an egg outside the body, in a laboratory setting, before transferring the resulting embryo back into the uterus.

Illustration depicting the in vitro fertilization process, highlighting egg retrieval from the ovary, fertilization in a petri dish, and embryo transfer to the uterus.

Often referred to simply as IVF, this treatment is a sophisticated solution for infertility, defined as the inability to conceive after one year of unprotected intercourse for most couples. Beyond infertility, IVF also provides a crucial option for preventing the transmission of genetic disorders to offspring. It stands as the most potent form of fertility treatment involving the manipulation of eggs and sperm, falling under the umbrella of assisted reproductive technologies.

During a typical IVF cycle, mature eggs are meticulously retrieved from the ovaries and then fertilized by sperm in a specialized laboratory. Subsequently, one or more of these fertilized eggs, now termed embryos, are carefully placed into the uterus – the nurturing environment where a baby develops during pregnancy. A complete IVF cycle typically spans approximately two to three weeks, although this timeline can sometimes extend if the process is strategically divided into distinct stages.

IVF can utilize a couple’s own eggs and sperm, or it may incorporate eggs, sperm, or embryos sourced from either known or anonymous donors. In certain situations, a gestational carrier, a woman who receives an embryo implant to carry the pregnancy, may be involved.

The likelihood of achieving a successful and healthy pregnancy through IVF is influenced by a multitude of factors, notably including the age of the individual undergoing treatment and the underlying causes of infertility. It’s important to acknowledge that IVF is a journey that can be emotionally, physically, and financially demanding. Furthermore, the transfer of multiple embryos can lead to multiple pregnancies, which carries its own set of considerations and potential risks.

A dedicated healthcare team plays a vital role in guiding individuals through the intricacies of IVF, providing comprehensive information about the procedure, potential risks, and whether IVF aligns with their specific needs and circumstances.

Why is In Vitro Fertilization Performed?

In vitro fertilization serves as a primary treatment for both infertility and genetic concerns. Before embarking on IVF for infertility, it’s often advisable to explore less invasive fertility treatments first. Options such as fertility medications, designed to stimulate increased egg production by the ovaries, or intrauterine insemination (IUI), which involves the direct placement of sperm into the uterus around ovulation, may be considered.

However, IVF emerges as a leading treatment option in several specific scenarios, including for individuals over 40 or when particular health conditions are present. Specifically, IVF may be recommended if you or your partner face any of the following:

Fallopian tube damage or blockage: The fallopian tubes are the critical pathways for eggs traveling from the ovaries to the uterus. Damage or blockages in these tubes can impede fertilization and embryo transport.
Ovulation disorders: Irregular or absent ovulation means fewer eggs are available for fertilization.
Endometriosis: This condition involves the growth of uterine-lining-like tissue outside the uterus, often impacting the ovaries, uterus, and fallopian tubes.
Uterine fibroids: These non-cancerous tumors in the uterus, common in women in their 30s and 40s, can interfere with embryo implantation.
Prior tubal ligation: For individuals who have undergone tubal ligation (permanent birth control) and now desire pregnancy, IVF can offer a solution, potentially avoiding the need for tubal ligation reversal surgery.
Sperm-related issues: Low sperm count, poor sperm motility (movement), or abnormal sperm morphology (shape) can hinder natural fertilization.
Unexplained infertility: When the cause of infertility remains unidentified despite thorough testing, IVF may be recommended.
Genetic disorders: For couples at risk of passing on a genetic disorder, preimplantation genetic testing (PGT) in conjunction with IVF allows for embryos to be screened for specific genetic problems before uterine transfer.
Fertility preservation: Individuals facing cancer treatments like chemotherapy or radiation, which can impair fertility, can utilize IVF to preserve their eggs or embryos for future use.

Furthermore, IVF with a gestational carrier is an option for women without a functional uterus or for whom pregnancy poses significant health risks. In these cases, the intended parents’ eggs and sperm are used to create embryos, which are then implanted into the gestational carrier’s uterus.

For those considering IVF, seeking a consultation to discuss individual circumstances and explore whether IVF is the appropriate path forward is a crucial first step.

Potential Risks Associated with IVF

While IVF offers remarkable possibilities, it’s essential to be aware of the potential risks involved, both in the short and long term:

Emotional and Physical Stress: IVF can be emotionally taxing, physically demanding, and financially burdensome. Seeking support from counselors, family, and friends is crucial to navigate the emotional rollercoaster of infertility treatment.
Complications from Egg Retrieval: The egg retrieval procedure, which involves using a needle to extract eggs from ovarian follicles, carries risks such as bleeding, infection, and damage to adjacent organs like the bowel, bladder, or blood vessels. Anesthesia-related risks are also associated with the sedation used during the procedure.
Ovarian Hyperstimulation Syndrome (OHSS): This condition involves excessive ovarian swelling and pain, triggered by fertility medications used to stimulate ovulation. Symptoms can range from mild abdominal pain and bloating to, in rare cases, severe complications like rapid weight gain and shortness of breath.
Miscarriage: The miscarriage rate after IVF using fresh embryos is comparable to natural conception rates, increasing with maternal age – from approximately 15% in the 20s to over 50% in the 40s.
Ectopic Pregnancy: In a small percentage of IVF pregnancies, the embryo implants outside the uterus, typically in a fallopian tube, resulting in a non-viable pregnancy.
Multiple Pregnancy: IVF increases the likelihood of multiple pregnancies (twins, triplets, or more), which elevates the risks of pregnancy-related complications like gestational hypertension, gestational diabetes, preterm labor and delivery, low birth weight, and birth defects compared to singleton pregnancies.
Birth Defects: While maternal age is the primary risk factor for birth defects, some studies suggest a slightly elevated risk of certain birth defects, such as heart or digestive system issues, in babies conceived through ART, including IVF. Further research is needed to determine if IVF directly contributes to this increased risk.
Premature Birth and Low Birth Weight: Research indicates a slightly higher chance of premature birth and low birth weight in infants born after IVF.
Cancer Concerns: Early studies suggested a potential link between fertility medications and ovarian tumors, but more recent and robust research has not substantiated these findings. Current evidence does not indicate a significantly increased risk of breast, endometrial, cervical, or ovarian cancer following IVF.

Understanding these potential risks empowers individuals to make informed decisions and engage in thorough discussions with their healthcare providers.

Preparing for In Vitro Fertilization

Initiating the IVF journey begins with selecting a reputable fertility clinic. For those in the United States, resources like the Centers for Disease Control and Prevention (CDC) and the Society for Assisted Reproductive Technology (SART) provide online information about clinic-specific pregnancy and live birth rates.

It’s important to recognize that a clinic’s success rates are influenced by various factors, including patient demographics, medical histories, and the clinic’s treatment protocols. When consulting with a clinic, inquire about detailed cost breakdowns for each stage of the IVF process.

Prior to commencing an IVF cycle using your own eggs and sperm, both partners will typically undergo several screening tests:

Ovarian Reserve Testing: Blood tests and potentially an ultrasound of the ovaries assess the quantity and quality of a woman’s eggs, predicting ovarian response to fertility medications.
Semen Analysis: A semen sample is analyzed to evaluate sperm count, morphology, and motility.
Infectious Disease Screening: Both partners are screened for infectious diseases like HIV.
Practice Embryo Transfer: This mock transfer helps determine uterine depth and optimize the technique for actual embryo transfer.
Uterine Exam: Evaluations like sonohysterography or hysteroscopy assess the uterine lining for any abnormalities.

Before starting IVF, it’s also crucial to consider key questions:

Number of Embryos to Transfer: The number of embryos transferred is typically determined by age and egg quantity. To minimize the risk of high-order multiple pregnancies (triplets or more), guidelines are usually followed, and some countries have legal limits on embryo transfer numbers. Discuss and agree upon the number of embryos to be transferred with your care team.
Disposition of Extra Embryos: Surplus embryos can be cryopreserved (frozen) for future IVF cycles, donation to other couples or research, or discarded. Decisions regarding extra embryos should be made proactively.
Managing Multiple Pregnancy: Understand the risks associated with multiple pregnancies and discuss options like fetal reduction, if relevant, although this is a complex decision with ethical and emotional implications.
Considerations for Donor Gametes or Gestational Carrier: If using donor eggs, sperm, or embryos, or a gestational carrier, seek counseling to address legal and emotional aspects, including donor rights and parental rights. Legal counsel may be necessary to establish legal parentage.

Thorough preparation and open communication with your healthcare team are essential steps for a well-informed and empowered IVF experience.

What to Anticipate During the IVF Process

A single IVF cycle typically takes around two to three weeks, and multiple cycles may be necessary. The IVF process unfolds in several key stages:

Ovarian Stimulation for Mature Egg Development

The IVF cycle commences with hormonal medications designed to stimulate the ovaries to produce multiple mature eggs, rather than the single egg that typically matures each menstrual cycle. Multiple eggs are desired because not all eggs will successfully fertilize or develop into viable embryos after fertilization.

Medications used during this phase may include:

Ovarian Stimulation Medications: Injections of follicle-stimulating hormone (FSH), luteinizing hormone (LH), or a combination of both, encourage the development of multiple follicles (egg-containing sacs) in the ovaries.
Ovulation Maturation Medications: Human chorionic gonadotropin (HCG) or other medications help the eggs mature fully and prepare for release from the follicles.
Ovulation Prevention Medications: These medications prevent premature egg release (ovulation) before retrieval.
Uterine Lining Preparation Medications: Progesterone supplements, initiated around egg retrieval or embryo transfer, enhance the receptivity of the uterine lining to embryo implantation.

The specific medications and their timing are tailored by your physician. Ovarian stimulation typically lasts one to two weeks, monitored by:

Vaginal Ultrasound: To track follicle development within the ovaries.
Blood Tests: To monitor hormone levels (estrogen and progesterone) and assess ovarian response to stimulation.

In some instances, an IVF cycle may be canceled before egg retrieval due to:

Insufficient follicle development.
Premature ovulation.
Excessive follicle development (OHSS risk).
Other medical concerns.

In case of cancellation, adjustments to medications or alternative approaches, including egg donation, may be discussed for future cycles.

Egg Retrieval Procedure

Egg retrieval is performed as an outpatient procedure in a clinic or doctor’s office, typically 34 to 36 hours after the final ovulation maturation injection and just prior to ovulation.

Anesthesia or sedation is administered for comfort and pain prevention.
Transvaginal ultrasound aspiration is the most common technique: an ultrasound probe guides a needle through the vagina into the ovarian follicles to aspirate (collect) the eggs.
In rare cases where transvaginal access is not feasible, abdominal ultrasound guidance may be used to retrieve eggs through the abdominal wall.
The aspirated fluid from the follicles, containing the eggs, is collected via a suction device connected to the needle.
The procedure typically takes around 20 minutes, and post-procedure cramping or pressure is common.
Retrieved eggs are placed in a culture medium to mature further. Healthy, mature eggs are selected for fertilization. Not all retrieved eggs will be suitable for fertilization.

Sperm Retrieval

If using partner sperm, a semen sample is collected on the morning of egg retrieval at the clinic or doctor’s office, or previously collected and frozen sperm may be used.

Semen collection typically involves masturbation.
Alternative sperm retrieval methods, such as testicular aspiration (using a needle or surgery to extract sperm directly from the testicle), may be employed if ejaculation is not possible or if there is no sperm in the ejaculate.
Donor sperm is also an option.
In the lab, sperm are separated from the seminal fluid.

Fertilization Methods

Two primary fertilization methods are used in IVF:

Conventional Insemination: Healthy sperm and mature eggs are combined in a petri dish and incubated, allowing fertilization to occur naturally.
Intracytoplasmic Sperm Injection (ICSI): A single healthy sperm is directly injected into each mature egg. ICSI is often preferred when sperm quality or quantity is compromised or if previous IVF cycles using conventional insemination have failed.

Additional procedures may be considered in certain situations:

Assisted Hatching: This technique involves creating a small opening in the embryo’s outer layer (zona pellucida) prior to uterine transfer to facilitate embryo hatching and implantation. It may be considered for older individuals, those with previous failed IVF cycles, or when using frozen eggs or embryos (as freezing can harden the zona pellucida).
Preimplantation Genetic Testing (PGT): Embryos are cultured until they reach a stage where a few cells can be biopsied for genetic analysis. PGT screens embryos for specific genetic disorders or chromosomal abnormalities before transfer, reducing the risk of transmitting genetic conditions. Prenatal testing during pregnancy may still be recommended even after PGT.

Embryo Transfer Procedure

Illustration demonstrating the egg retrieval technique, where a needle guided by transvaginal ultrasound aspirates eggs from ovarian follicles.

Diagram illustrating intracytoplasmic sperm injection (ICSI), where a single sperm is directly injected into an egg.

Image of a blastocyst, a developed embryo stage approximately five to six days post-fertilization, ready for uterine implantation.

Embryo transfer, the procedure to place embryos into the uterus, is typically performed at the clinic or doctor’s office two to six days after egg retrieval.

A mild sedative may be offered for relaxation. The procedure is usually painless, although mild cramping may occur.
A catheter, a thin, flexible tube, is inserted through the vagina and cervix into the uterus.
A syringe containing the embryo(s) in a small volume of fluid is attached to the catheter.
The embryo(s) are gently deposited into the uterus.

Implantation, where the embryo attaches to the uterine lining, typically occurs about six to ten days after egg retrieval if the procedure is successful.

Post-Embryo Transfer Care

After embryo transfer, you can generally resume normal daily activities, but strenuous activity and intercourse may be discouraged due to potential ovarian enlargement. Consult your care team for specific recommendations.

Common side effects after embryo transfer include:

Mild clear or blood-tinged vaginal discharge (due to cervix swabbing).
Breast tenderness (from elevated estrogen levels).
Mild bloating and cramping.
Constipation.

Contact your care team for moderate to severe pain or heavy vaginal bleeding, which could indicate complications like infection, ovarian torsion, or OHSS.

Understanding IVF Results

Approximately 12 days post-egg retrieval, a blood pregnancy test is performed.

Positive Pregnancy Test: If pregnant, you will be referred for prenatal care.
Negative Pregnancy Test: If not pregnant, progesterone supplementation is discontinued, and menstruation should occur within a week. Contact your care team if menstruation does not occur or if you experience unusual bleeding. Further IVF cycles and strategies to improve success chances may be discussed.

The success rate of IVF, defined as the chance of delivering a healthy baby, is influenced by several factors:

Maternal Age: Younger individuals have higher IVF success rates using their own eggs. Women aged 40 and older are often advised to consider donor eggs to enhance success.
Embryo Quality: More developed embryos at transfer stage are associated with higher pregnancy rates, but not all embryos develop successfully. Discuss embryo quality with your care team.
Reproductive History: Individuals with a prior history of live birth have a higher chance of IVF success compared to those who have never given birth. Success rates tend to decrease with multiple unsuccessful IVF cycles.
Cause of Infertility: Individuals with adequate ovarian reserve have better IVF outcomes. Severe endometriosis may reduce IVF success compared to unexplained infertility.
Lifestyle Factors: Smoking negatively impacts IVF success, reducing egg quantity and increasing miscarriage risk. Obesity can also decrease pregnancy and live birth rates. Alcohol, drug use, excessive caffeine, and certain medications can also be detrimental.

Discuss your individual factors with your care team to understand their potential influence on your IVF success.

Clinical Trials and Advancements in IVF

Explore Mayo Clinic studies actively researching and advancing IVF techniques and related fertility treatments. Clinical trials are crucial for improving IVF outcomes and addressing remaining challenges in reproductive medicine.

By Mayo Clinic Staff