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When undergoing in vitro fertilization (IVF), one of the most critical decisions you and your medical team will make is the number of embryos to transfer. This decision can significantly impact the success of your treatment, as well as the health of both the mother and the resulting child(ren). In this post, we'll discuss the factors that influence this decision and the recommendations provided by the American Society for Reproductive Medicine (ASRM).

The Goal: Balancing Success and Safety

The primary objective when deciding on the number of embryos to transfer is to maximize the chances of achieving a successful pregnancy while minimizing the risk of multiple pregnancies. Multiple pregnancies, such as twins or triplets, can pose serious health risks for both the mother and the babies. Therefore, the ideal outcome is a singleton pregnancy.

ASRM Guidelines: Factors to Consider

The ASRM provides recommendations on the number of embryos to transfer based on several factors, including:

1. Age of the patient
2. Quality and stage of embryo development
3. Other clinical considerations (e.g., history of implantation failure, or certain medical conditions)

In most cases, the ASRM recommends transferring a single embryo, especially for patients under 38 years old. However, for patients over 38 using their own eggs, the transfer of multiple embryos may be considered due to the increased likelihood of chromosomal abnormalities in the embryos as the age of the eggs increases.

‍The Role of Preimplantation Genetic Testing (PGT)

‍Preimplantation Genetic Testing for Aneuploidies (PGT-A) is a procedure that analyzes the chromosomal composition of embryos before transfer. If PGT-A indicates that an embryo is chromosomally normal (euploid), a single embryo transfer is highly recommended, regardless of the patient's age. This testing can help identify the most promising embryos, increasing the chances of a successful singleton pregnancy.

To learn more about Orchid's Preimplantation Genetic Testing, read our latest guide: What’s in Orchid’s Embryo Report?

‍Age and IVF Success Rates

‍For patients under 35 using their own eggs, the chances of achieving a successful singleton pregnancy are similar whether one or two embryos are transferred. However, transferring two embryos in this age group results in a twin pregnancy in at least 25% of cases. As the patient's age increases, the likelihood of chromosomal abnormalities in the embryos also rises, leading to lower pregnancy rates and higher miscarriage rates—even when using fertility treatments.

‍The Possibility of Embryo Splitting

‍In rare cases (less than 3% of cycles), a single transferred embryo can split, resulting in identical twins. When two embryos are transferred, there is also a small chance (less than 3%) of one embryo splitting, potentially leading to a triplet pregnancy. The transfer of two embryos, both of which split, could, in extremely rare instances, result in quadruplets.

Deciding on the number of embryos to transfer during IVF is a complex and critical choice that should be made in consultation with your medical team. Factors such as age, embryo quality, and PGT results all play a role in determining the best approach for each individual case. By carefully considering these factors and following ASRM guidelines, you and your medical team can work together to maximize the chances of a successful singleton pregnancy while minimizing the risks associated with multiple pregnancies.

The content on this blog is for informational purposes only and is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always consult with a qualified healthcare provider before making any health-related decisions or implementing any medical information shared here.