In Vitro Fertilization: Everything You Need to Know
At Fertilidad Integral, we know that taking the step toward an assisted reproduction treatment like in vitro fertilization (IVF) involves many questions, emotions, and important decisions. That’s why we want to accompany you with clear information, supported by scientific evidence and our clinical expertise.
IVF is one of the most effective fertility treatments worldwide and has enabled millions of families to achieve pregnancy when other options have not succeeded. Here we explain what IVF involves, who can benefit from this treatment, how each stage works, and what to expect throughout the process.
What is In Vitro Fertilization (IVF)?
In vitro fertilization (IVF) is an assisted reproductive technology in which an egg is fertilized by sperm outside the woman’s body, in an embryology laboratory. Once fertilization occurs and the embryo develops, it is transferred into the uterus to achieve pregnancy.
Unlike sexual intercourse or intrauterine insemination (IUI), where fertilization takes place inside the body, IVF involves:
- Stimulating the ovaries to produce multiple mature eggs
- Fertilizing the eggs under controlled laboratory conditions
- Monitoring embryo development over several days
- Selecting the embryo(s) with the highest potential for implantation
- Transferring the embryo into the uterus using a thin, flexible catheter
IVF has transformed the way families can be created — offering hope and new possibilities for those who need support to achieve a healthy pregnancy.
Brief history and evolution
The first successful birth through in vitro fertilization (IVF) took place in 1978, a milestone that completely transformed the field of assisted reproduction. Since then, technological advancements, improved culture media, and enhanced methods for embryo assessment have significantly increased the chances of achieving a successful pregnancy.
More recently, technologies such as vitrification have optimized the preservation of embryos and eggs, while artificial intelligence has enabled a more objective and personalized embryo selection. Together, these innovations have established IVF as a safe and highly reliable treatment option for individuals and couples facing reproductive challenges.
Differences between IVF, Intrauterine Insemination (IUI) and ICSI
Not all fertility treatments are the same, each is recommended based on the underlying cause of infertility.
IVF vs. Intrauterine Insemination (IUI)
The main difference between in vitro fertilization (IVF) and intrauterine insemination (IUI) lies in where fertilization occurs: in IUI, it happens inside the woman’s body, while in IVF it takes place in the laboratory.
IUI is considered a low-complexity treatment, recommended for mild infertility cases such as slightly altered semen parameters or irregular ovulation. In contrast, IVF is a high-complexity procedure indicated in situations like endometriosis or diminished ovarian reserve, and it generally offers a higher probability of success.
IVF vs. ICSI (Intracytoplasmic Sperm Injection)
ICSI is a technique within IVF that involves the microinjection of a single sperm cell into each egg.
Both conventional IVF and ICSI are advanced assisted reproduction techniques, but they differ in how fertilization is achieved. In conventional IVF, eggs and sperm are placed together in the laboratory so fertilization can occur naturally. In contrast, ICSI involves selecting a single sperm and injecting it directly into the egg, making it especially useful in cases of severe male factor infertility or when there is a history of failed fertilization with conventional IVF.
The choice between conventional IVF and ICSI is never automatic. At Fertilidad Integral, the recommendation is made after a thorough evaluation of each patient’s diagnosis and reproductive potential, to ensure the best strategy for every treatment.
Who is a candidate for IVF?
Individuals or couples who have been trying to conceive for 6 to 12 months without success, depending on age and medical history may be candidates for IVF. This treatment is typically recommended when there are factors that affect egg quality or availability, the function of the fallopian tubes, sperm health, or the ability of the egg and sperm to fertilize naturally.
IVF is also a suitable option for those who have experienced unsuccessful outcomes with previous treatments such as intrauterine insemination (IUI), and for women without a male partner or same-sex couples who require donor gametes to achieve pregnancy.
In every case, the recommendation for IVF is made after a comprehensive medical evaluation to identify the cause of infertility and determine the treatment strategy with the highest chance of success.
Why is IVF performed and in which cases is it recommended?
Ovulatory disorders
IVF is recommended when ovulatory dysfunction prevents the regular release of mature eggs. These alterations may be caused by hormonal imbalances, polycystic ovary syndrome (PCOS), or other conditions that reduce the chances of spontaneous fertilization.
Endometriosis
In cases of endometriosis, the presence of endometrial tissue outside the uterus can affect egg quality, cause pelvic inflammation, and alter reproductive anatomy, making natural fertilization more difficult. IVF helps overcome these barriers and increases the chance of pregnancy.
Previous treatment failures
When lower-complexity treatments such as ovulation induction or intrauterine insemination (IUI) have not been successful after several attempts, IVF is recommended as the next step due to its higher efficacy.
Diminished ovarian reserve
A decrease in egg quantity and/or quality whether due to age or specific medical conditions significantly reduces the likelihood of natural conception. IVF optimizes the retrieval and selection of the remaining eggs to improve reproductive outcomes.
Male factor infertility
Alterations in semen parameters such as concentration, motility, or morphology may hinder fertilization. In these cases, IVF particularly through ICSI enables the sperm to directly fertilize the egg, improving the chances of successful fertilization.
Same-sex couples and single mothers by choice
IVF provides a safe and accessible reproductive option for women without a male partner and for female same-sex couples, using donor sperm or other assisted reproduction techniques, always respecting and supporting each person’s unique family-building journey.
Types of IVF
IVF can be tailored to different clinical needs and family-building models through the use of either own or donor gametes. The choice of treatment depends on the reproductive diagnosis and the goals of each individual or couple.
IVF with own eggs and partner’s sperm
This is the most common approach when both eggs and sperm are suitable for use. Fertilization takes place in the laboratory using the couple’s gametes, with the goal of creating an embryo that will later be transferred to the uterus.
IVF with own eggs and donor sperm
Indicated when a significant male factor infertility issue is present, or for women without a male partner. Donor sperm allows the maternal genetic contribution to be maintained while ensuring optimal sperm quality for fertilization.
IVF with donor eggs and partner’s sperm
Recommended when ovarian reserve is compromised or egg quality is insufficient to achieve pregnancy. Egg donation provides healthy female genetic material while preserving the male partner’s genetic contribution.
IVF with donor eggs and donor sperm
Used when neither partner’s gametes can be used, or when this approach is chosen for personal reasons or medical recommendations. This is a safe and effective path for individuals facing complex reproductive conditions who wish to build a family.
Requirements and preparation before starting IVF treatment
Before beginning in vitro fertilization, it is essential to undergo a complete medical evaluation and consider various factors that may influence treatment outcomes. This stage ensures a safe procedure and helps optimize the likelihood of success.
Medical assessments
Preparation includes a set of tests designed to evaluate both reproductive and overall health. These may include hormonal profile testing such as antimüllerian hormone (AMH) to measure ovarian reserve transvaginal ultrasound to assess follicles, and semen analysis to evaluate sperm quality. Blood tests, infectious disease screening, and other complementary assessments are also performed to define the most appropriate treatment strategy.
Lifestyle and contributing factors
Habits such as smoking, excessive alcohol intake, sedentary lifestyle, and being overweight can negatively impact egg, sperm, and endometrial quality. For this reason, maintaining a healthy lifestyle, regular physical activity, balanced nutrition, and stress management is recommended. Preparing the body and ensuring optimal health supports a better response to treatment and a healthier pregnancy.
Psychological support
The reproductive process can involve significant emotional stress due to expectations, time investment, and the variability of treatment outcomes. Specialized psychological support is encouraged to help individuals and couples navigate the experience with greater emotional well-being. Professional guidance can reduce anxiety, strengthen communication, and sustain motivation throughout the process.
Steps of the IVF cycle
Each stage is carried out under specialized medical supervision to ensure safety and optimize outcomes.
Ovarian stimulation
During this phase, hormonal medications are administered to stimulate the development of multiple ovarian follicles. The goal is to obtain an adequate number of mature eggs to increase the chances of creating viable embryos. Ultrasound monitoring and hormonal tests are performed throughout the process to track the response and adjust treatment as needed.
Egg retrieval (follicular aspiration)
Once the follicles reach the appropriate size, the egg retrieval procedure is scheduled. Performed under light sedation, it consists of aspirating the eggs using a fine needle guided by ultrasound. This is a brief, outpatient procedure, after which the patient can resume daily activities with caution.
Embryo culture
After fertilization, embryos are placed in specialized incubators designed to mimic optimal developmental conditions. Their growth is monitored until they reach the blastocyst stage, typically on days five or six of culture. Selection is based on morphology and implantation potential to choose the embryo with the highest likelihood of success.
Embryo transfer
The selected embryo is placed into the uterine cavity using a thin catheter. This is a simple procedure that does not require anesthesia. The transfer may be performed in a fresh cycle or deferred through embryo freezing, depending on clinical needs and endometrial readiness.
If you would like to learn more about each stage of the IVF process, you can visit our specialized article covering the complete IVF journey.
After the procedure: what to expect
Mild side effects
After the transfer, some patients may experience mild abdominal bloating, breast tenderness, cramping, or light pelvic discomfort. These effects are usually temporary and are related to ovarian stimulation and progesterone supplementation, a hormone that supports implantation. Light vaginal spotting may also occur, which does not necessarily indicate a negative outcome.
Post-procedure care
During this period, it is recommended to maintain a calm daily routine, avoiding intense physical effort, high-impact exercise, and sexual intercourse during the first few days. It is also important to follow the prescribed medication schedule and prioritize proper rest, hydration, and stress management. If severe symptoms occur such as intense pain, difficulty breathing, or heavy bleeding, the medical team should be contacted immediately.
When to take the pregnancy test
The outcome of the procedure is assessed through a blood pregnancy test, usually 10 to 14 days after the embryo transfer. This test detects human chorionic gonadotropin (hCG), a hormone that confirms successful implantation. A second test may be necessary to ensure appropriate pregnancy progression if the result is positive
IVF success rates and outcomes
The success of IVF is influenced by a variety of biological and clinical factors, so results may vary from patient to patient. A thorough evaluation and a personalized treatment plan help optimize the likelihood of achieving a healthy, ongoing pregnancy.
Factors that influence success
The outcome of IVF depends on several elements involved throughout the process. Age and ovarian reserve are key, as they determine the number and quality of available eggs. Likewise, embryo quality assessed during laboratory culture, along with endometrial receptivity at the time of transfer, directly affects the chances of implantation.
Male factor infertility including sperm concentration, motility, and morphology can also impact fertilization and may require specific techniques such as ICSI. Additionally, laboratory technology, monitoring and traceability systems, and the expertise of the medical team are essential to ensure safe procedures and the highest likelihood of a favorable outcome.
Average success rates by age
Globally, there is a natural decline in pregnancy rates as maternal age increases:
*International references (SART). Average live birth rates per IVF cycle in 2020.
Fertilidad Integral success rates
Laboratory performance is one of the most important indicators in assisted reproduction. At Fertilidad Integral, we use state-of-the-art technologies and follow strict quality standards. This is reflected in the following clinical outcomes: