Developments in IVF treatments continue to be a beacon of hope for thousands of couples dreaming of having children. However, one of the crucial decisions on this hopeful journey is the number of embryos to be transferred. Traditionally, multiple embryo transfers were performed to increase the chances of pregnancy. Yet, the modern IVF approach, especially in recent years, has brought single embryo transfer to the forefront in IVF (In Vitro Fertilization) treatments, focusing on the goal of a healthy single baby. As Prof. Dr. Mehmet Çınar, we will discuss the scientific facts behind this approach, which we implement at our Ankara IVF Center, and its contributions to maternal and infant health in this article.
Why Are Multiple Pregnancies Risky?
While having twins or triplets may sound appealing to most couples, from a medical perspective, multiple pregnancies carry significant risks for both the mother and the babies. These risks significantly increase compared to singleton pregnancies and can make pregnancy monitoring and the birth process more complex.
Risks for the Expectant Mother:
- Risk of Premature Birth: The rate of premature birth (before 37 weeks) is much higher in multiple pregnancies. This can negatively affect the babies' development.
- Preeclampsia (Pregnancy Poisoning): This severe condition, characterized by high blood pressure, protein in the urine, and organ damage, is more common in multiple pregnancies.
- Gestational Diabetes: The risk of pregnancy-related diabetes increases.
- Anemia: The risk of anemia in the expectant mother increases.
- Placental Problems: Conditions such as placental abruption (early detachment of the placenta) or placenta previa (placenta covering the cervix) are more likely.
- Postpartum Hemorrhage: The risk of excessive bleeding after birth due to insufficient uterine muscle contraction increases.
- Need for Cesarean Section: A significant portion of multiple pregnancies result in a Cesarean section.
- Psychological and Physical Fatigue: The increased physical and psychological burden during and after pregnancy can reduce the mother's quality of life.
Risks for Babies (Twin Pregnancy Risks):
- Premature Birth and Low Birth Weight: Premature and low-birth-weight babies may experience many health problems, such as respiratory issues, feeding difficulties, infections, and developmental delays.
- Need for Neonatal Intensive Care: The vast majority of premature babies require monitoring and treatment in a neonatal intensive care unit.
- Developmental Problems: Long-term developmental problems such as cerebral palsy, visual and hearing impairments, and learning difficulties are more frequently observed among twin pregnancy risks.
- Twin-to-Twin Transfusion Syndrome (TTTS): This serious condition, which can occur especially in identical twins, involves one baby transferring blood to the other, threatening the health of both babies.
- Congenital Anomalies (Birth Defects): The incidence of birth defects can increase in multiple pregnancies.
- Neonatal Mortality Rate: Unfortunately, infant mortality rates are higher in multiple pregnancies compared to singleton pregnancies.
Given these risks, the primary goal in modern IVF treatment is to minimize these risks and achieve a healthy pregnancy and a single, healthy baby. Therefore, being aware of the risks of multiple pregnancies is critically important in determining treatment strategies.
Who is Single Embryo Transfer For?
Single Embryo Transfer (SET) has become one of the most important success criteria in contemporary IVF treatment. This approach aims to eliminate the aforementioned multiple pregnancy risks while maintaining a high chance of pregnancy. So, who should undergo single embryo transfer?
In fact, current scientific data and international guidelines recommend single embryo transfer in every possible situation. Single embryo transfer is strongly recommended, especially in the following cases:
- Patients with Good Prognosis:
- Younger Age Group (under 35): Younger women generally have better egg quality and, consequently, better embryo quality. In this group, high pregnancy rates can be achieved with a single high-quality embryo.
- First IVF Attempt: Single embryo transfer is preferred for patients undergoing IVF treatment for the first time and who have good quality embryos.
- Those with Previous Pregnancy Success: Single embryo transfer is also recommended for patients who have previously had a successful pregnancy or live birth.
- High-Quality Embryos: The transfer of embryos that have reached the blastocyst stage (day 5 or 6 embryo) and are morphologically determined to be of excellent quality offers a high chance of pregnancy even alone.
- Patients Undergoing Preimplantation Genetic Testing (PGT): The transfer of embryos genetically confirmed as normal via PGT increases the chance of pregnancy while reducing the risk of miscarriage. In this case, the transfer of a single genetically healthy embryo is sufficient and ideal.
- Those with a History of Recurrent Miscarriage: Especially in patients experiencing miscarriages due to chromosomal abnormalities, single embryo transfer combined with PGT increases the chance of achieving a healthy pregnancy.
- Those with Uterine Health Risks: Structural problems in the uterus, a history of uterine surgery, or conditions where multiple pregnancy would pose additional risks to maternal health (e.g., heart disease, chronic illnesses) may necessitate single embryo transfer.
Each patient's situation should be assessed individually, and the treatment plan should be determined on a personalized basis. Throughout the IVF process, as Prof. Dr. Mehmet Çınar, we conduct detailed consultations with our patients at our Ankara IVF Center to jointly determine the most suitable treatment strategy. Our goal is to achieve a healthy pregnancy through the safest and most effective methods.
The Contribution of Blastocyst and PGT
In modern IVF treatment, there are two significant technological advancements that support the single embryo transfer approach and increase success rates: Blastocyst transfer and Preimplantation Genetic Testing (PGT).
Blastocyst Transfer:
Embryos divide and develop within the first few days after fertilization. Traditionally, embryos were transferred on day 2 or 3 (cleavage stage). However, with the improvement of laboratory conditions, it has become possible to cultivate embryos in the laboratory environment until day 5 or 6. This stage is called a "blastocyst."
- Natural Selection: Embryos that can reach the blastocyst stage are stronger and have a higher potential for survival. This provides a natural selection process among embryos.
- Higher Implantation Rate: Blastocysts have higher implantation rates because they are more synchronized with the uterine lining.
- Success of Single Embryo Transfer: The transfer of a blastocyst with high implantation potential offers a high chance of pregnancy even alone. This makes it easier to achieve the goal of a healthy single baby, avoiding the risk of multiple pregnancies.