Classically, in vitro fertilization (IVF) treatment begins on the 2nd or 3rd day of the menstrual cycle. After an ultrasound check during this period, the treatment starts with daily hormone injections (gonadotropins) administered subcutaneously in the abdominal area to stimulate the eggs in the ovaries. The egg maturation process takes an average of 8-14 days. During this period, ultrasound examinations are performed at regular intervals to monitor the development of the eggs. On the 6th day of gonadotropin treatment, a different injection called a GnRH antagonist is started to prevent the eggs from rupturing prematurely. When at least 3 follicles (structures containing the eggs) reach sizes of 18mm or more, an hCG injection is administered to mature the eggs, and 36 hours after this injection, the egg retrieval procedure is performed.
The egg retrieval procedure is performed in an operating room under sedation anesthesia administered intravenously (inducing a sleep state). Follicles containing the egg cells are aspirated using a needle guided by transvaginal ultrasound. The collected follicular fluids are examined by an embryologist, and the identified eggs are transferred to a special culture medium in an incubator.
If sperm parameters are normal, approximately 50,000-100,000 motile sperm cells are placed into the culture medium containing the eggs, and fertilization is monitored through insemination.
In the ICSI (intracytoplasmic sperm injection) method, a single sperm selected by the embryologist under a high-magnification microscope is directly injected into the egg cell. The likelihood of fertilization is higher with the ICSI method, and it is used for couples with low sperm parameters or when sperm is surgically obtained from the testis.
Whether fertilization has occurred is evaluated 16-18 hours after the insemination or ICSI procedure. Fertilized eggs are called ‘zygotes’ and are monitored in a special culture medium that supports their development. A re-evaluation is done on the 2nd or 3rd day after the egg retrieval procedure. If there are a sufficient number of high-quality embryos, they can be monitored until the 5th day, reaching the blastocyst stage. In the presence of a small number or low-quality embryos, a 3rd-day embryo transfer may be preferred.
When evaluating embryo quality, various criteria are considered, such as the number of cells in the embryo, the uniformity of the cell sizes, and the low presence of cell debris known as fragmentation. On the day of the embryo transfer, the decision on which embryo to transfer is made based on the development stages and appearances of the available embryos.
Embryos are typically transferred at the cleavage stage (3 days after egg retrieval) or the blastocyst stage (5 days after egg retrieval). Embryo transfer is a simple procedure that does not require anesthesia. Embryos loaded into a soft catheter are placed into the uterus under ultrasound guidance. Transfers performed within 5 days following the egg retrieval without freezing the embryos are called fresh transfers. Pregnancy is determined 12 days after the embryo transfer with a beta-hCG blood test.
Good quality embryos remaining after the embryo transfer can be frozen and stored at the 3rd day or 5th day stage. Fresh embryo transfer may not be suitable for women with a high number of eggs after egg retrieval, abnormalities in the uterine lining, or early elevation of progesterone hormone. In such cases, all good quality embryos obtained are frozen without being transferred. Frozen embryos are thawed and transferred once more suitable conditions for pregnancy are achieved.
PGT is a genetic diagnostic method that can be applied during IVF treatment. It is used to detect genetic or hereditary abnormalities in embryos before the implantation process and to ensure the transfer of healthier embryos.
Normal human cells contain 46 chromosomes in their nucleus. Chromosomes are made up of DNA, which carries genetic information. Each person receives 23 chromosomes from their mother and 23 from their father. Errors in the number of chromosomes in the egg or sperm can result in embryos with missing or extra chromosomes. This condition is called aneuploidy. In most cases of aneuploidy, the embryo cannot implant in the uterus, or if it does, it results in a miscarriage. However, in the case of trisomy 21 (having three copies of chromosome 21 instead of two), implantation of the embryo can lead to Down Syndrome. PGT-A is a method used to detect numerical chromosomal abnormalities in embryos.
It can be applied in cases of recurrent pregnancy loss, in women aged 38 and above, in cases of repeated IVF failures, or in couples with hereditary genetic diseases such as cystic fibrosis or myotonic dystrophy.
A few cells are extracted from the outer cell layers of embryos that have reached the 5th or 6th day stage through biopsy, and the extracted cells are sent for genetic analysis. Embryos that undergo biopsy are frozen and stored. Embryos that are found to be normal after analysis can be thawed and transferred under suitable conditions.
The laboratory where IVF treatment is performed: One of the most important factors affecting success is the quality of the embryology laboratory where procedures involving eggs and sperm are carried out after egg retrieval, and the experience of the embryologists performing these procedures.
Age of the prospective mother: The ideal age range for pregnancy is between 20-35 years. As maternal age increases, the success rate of IVF treatment decreases due to declining egg quality and quantity. After the age of 40, egg quality continues to decline more rapidly, and the likelihood of pregnancy drops significantly after the age of 45.
Embryo Quality: The developmental stage and quality of the transferred embryo can affect pregnancy rates. Blastocyst embryos (5th or 6th day) have a higher likelihood of achieving pregnancy compared to 3rd-day embryos.
Duration of infertility and number of previous treatments: The longer the duration of infertility and the higher the number of unsuccessful IVF treatments, the lower the likelihood of pregnancy.
Previous pregnancy history: Patients who have previously given birth have a higher chance of becoming pregnant with IVF treatment compared to women who have never given birth.
Cause of infertility: Patients with a high number of eggs have a higher likelihood of successful IVF treatment compared to those with a low number of eggs. Women with a history of endometriosis have lower IVF success rates compared to those without endometriosis.
Lifestyle factors: Couples who smoke have lower success rates with IVF treatment and a higher likelihood of resulting pregnancies ending in miscarriage. Obese patients with a body mass index over 30 or couples with metabolic diseases such as insulin resistance have a lower chance of pregnancy.
In cases where a fresh transfer is performed, the treatment process is completed in approximately 3 weeks. For frozen-thawed embryo transfers, the process can take 6 weeks or longer.
For some couples undergoing IVF treatment, several attempts may be necessary to achieve pregnancy. Generally, it is recommended to wait at least one month between two IVF treatments due to economic and psychological factors. However, for couples with limited time, it is possible to start treatment again with the first menstrual cycle following a failed attempt.
In vitro fertilization (IVF) treatment is one of the most effective assisted reproductive techniques for infertile couples.
