By Dr Madhupriya
It has been three decades since IVF and medical science has advanced to introduce newer technologies to ensure the dream of parenthood for many couples. There are numerous fertility treatments and procedures that can help patients to achieve this dream, however, there are very few that offer the success rates of in vitro fertilisation or IVF. The process of IVF assists with most of the stages of conception to truly maximize a couple’s chance of becoming pregnant.
Fertility treatments can often be this complex and often require patients to make many decisions along the way as a lot of processes are involved behind a successful conception. After ovarian stimulation, egg retrieval, and fertilization, the final stage of IVF treatment is the embryo transfer and one of the key determinants of an effective pregnancy. In most cases, patients have multiple viable embryos that can be implanted, so often people end up injecting multiple embryos, just to increase the chance of pregnancy. However, this could end up complicating the whole process, involving multiple pregnancies. This situation comes with criticalities like second trimester miscarriage, preterm delivery, high blood pressures during pregnancy, low birth weight. Therefore, couples are advised to limit the number of embryos transferred through elective single-embryo transfer (eSET) to ensure a healthy pregnancy with the criticality of multiple births.
Elective Single-embryo Transfer involves a single embryo, selected from a larger number of available embryos, to be placed in the uterus. The embryo identified for eSET could be either a frozen embryo or from the current fresh IVF cycle that produced more than one embryo. The remaining embryos can be kept aside for future use through cryopreservation. This way women can evade risks known to be associated with giving birth to twins or what is called ‘high order multiple births’. Infants born this way more often end up being born early (preterm) with low birth weight and experience more adverse health outcomes than singleton infants.
There is a unanimity among fertility experts that the desired outcome of ART is a healthy singleton infant. And now it has been established that in a good fertility centre with top notch clinical and lab experts, Single Embryo Transfer has its success rate similar to Double Embryo Transfer, therefore, this can be opted as a more viable option in comparison to multi embryo transfer. With eSET, the patient does not have the mortality or morbidity of a twin pregnancy and ensures a safe conception.
Choosing the right embryo
When opting for a successful single embryo transfer, it is important to choose the highest-quality embryo. A successful implementation of eSET depends on the ability to select the most viable embryos in any cohort. The selection of the best embryo(s) for transfer continues to rely on morphologic evaluation, which has recognised shortcomings. This requires an advanced fertility laboratory involvement to grade each embryo based on its appearance and its growth, which includes evaluating at the number and size of the cells, their rate of development, and other contributing factors. Standardised grading systems are used to identify that one single embryo which can be eligible for successful conception, giving a good blastocyst (embryo) formation.
Who is suitable for eSET?
Varied parameters are prerequisites while considering eSET and should be obtainable to women who are apt to receive a single embryo instead of multiple embryos. For instance, patients who have not succeeded in getting pregnant through multiple IVF or ICSI cycles in the past and/or patients who are older than 35 years are not suitable for eSET, in some critical cases. However, freezing extra embryos and transferring in later cycles can provide a comparable pregnancy rate without the risks associated with twinning. One of the key benefits of choosing eSET has highlighted a dramatic drop in multiple pregnancy rates—overall, twin rates after eSET are very low, around 1%-2%.
This is not to deny the practice of multiple embryo transfer, but to encourage in considering eSET as a viable option if one is eligible, while carefully measuring all possible outcomes prior to the transfer procedure.
(The writer is Fertility Consultant, Nova IVF Fertility, Chennai)