Fertility Chronicles is proud to present a special blog series, “From the Fertility Experts,” where leading fertility experts answer commonly asked questions for patients about their fertility health and treatment options. We hope this series can help patients navigate their personal fertility journeys.—Catherine T. Yang, Editor, Fertility Chronicles
Our guest blogger Dr. George Grunert shares his advice on elective single embryo transfer (eSET):
The aim of fertility treatment is to help infertile couples have a safe, successful, healthy pregnancy. Multiple pregnancies, even twins, carry an increased risk for both the mother and the babies. Multiple pregnancies are associated with an increased chance of miscarriage, high blood pressure, toxemia, pre-eclampsia, diabetes, Caesarean section, premature labor, prolonged hospitalization, premature delivery, and hemorrhage. Primarily due to the higher rate of premature delivery (12% of twins will deliver before 32 weeks), children of multiple pregnancies are at increased risk of neurologic disease. Twins have a 12-fold higher chance of cerebral palsy than singletons, and triplets a 72-fold higher chance.
In the early days of IVF, the implantation rate of embryos (the chance that an embryo transferred to the uterus would result in a pregnancy) was low, about 5% to 15%. To compensate for this low success rate, multiple embryos were transferred. Occasionally, multiple embryos implanted, resulting in twin or higher order multiple pregnancies. This risk was felt to be an ‘acceptable side effect’ of the need to increase the number of embryos transferred to increase the pregnancy rate. With improvements in IVF laboratory technology (embryo culture abilities, extended culture to the blastocyst stage, preimplantation genetic screening, or PGS), we can now select embryos which are more likely to implant.
Elective single embryo transfer (eSET) is recommended for women who have a good chance of pregnancy, women in their first or second IVF cycle, or those who have had a previous successful IVF cycle, and are in one of these groups below and have two or more good quality embryos available for transfer:
We choose the best embryo for transfer based on its morphology (appearance and growth characteristic) and, if done, genetic results. Remaining good-quality embryo(s) are frozen for later transfer.
For example, for women meeting these criteria, who have two or more good quality embryos, eSET, compared with transfer of two fresh embryos, is associated with a slightly lower chance of pregnancy but results in an improved chance of a successful, term delivery. With the current vitrification technique of embryo freezing, the survival rate of frozen embryos is greater than 90%, and the pregnancy rates are identical with fresh embryo transfer cycles.
In the U.S., the community of reproductive endocrinologists has increasingly adopted the concept of eSET and has begun discussing this with patients. In other countries (the United Kingdom, the majority of European countries, Israel, Australia, and New Zealand), eSET is being promoted through legislation.
We believe so strongly in the benefit of eSET that in our program, if a woman meets the criteria for eSET and does not become pregnant with her initial fresh transfer, we will do her first frozen embryo transfer at no charge.
You can find more information on eSET at the American Society for Reproductive Medicine (ASRM) website.
Note from the Editor: Research has shown that a more comprehensive and personalized risk assessment through a multiple birth prediction test can reveal that more than half of the patients have significantly higher chances of multiple birth than previously thought, and many of these women would not have been identified as having high risk based on the criteria above. UnivfyIVFsingle test is currently available at Ottawa Fertility Center through a research trial and IVI-Valencia, Spain.