Is Single Or Multiple Embryo Transfer Better?
Many steps are required during in vitro fertilization (IVF) to achieve pregnancy. While retrieval and fertilization are both necessary, an embryo transfer is often considered the most important stage of IVF. During the transfer, 1 or more embryos are placed into the uterus. The number of embryos transferred can influence both success rates and potential risks. Advances in IVF now allow for more precise decision-making when considering different transfer approaches. Understanding available options helps patients make informed and confident choices.
From retrieval to transfer
During IVF, the patient is given medication to encourage the growth of multiple follicles. Once the follicles reach an optimal size, a trigger shot is administered to induce ovulation at a set time. A retrieval is then scheduled to collect the eggs under conscious sedation. Once retrieved, eggs are combined with sperm in the lab to create embryos. The embryos are then grown for 5-6 days before transfer into the uterus. Embryo transfer is a quick and minimally invasive procedure that does not require anesthesia in most cases.
Single embryo transfer benefits
In many cases, opting for a single embryo transfer (SET), which places 1 embryo in the uterus, is the best approach. Proceeding with SET significantly reduces the risk of multiple pregnancy, which can carry higher health risks for both mom and baby. Advances in embryo selection have improved success rates for single-embryo transfers. Preimplantation genetic testing (PGT), time-lapse imaging, extended embryo culture, and embryo grading help fertility specialists select the best embryo for transfer. Studies show that SET is safe and effective.
Opting to transfer multiple embryos
Less commonly, a doctor may advise multiple embryo transfer (MET) during IVF. MET involves placing 2 or more embryos into the uterus during the same cycle. This approach may be considered when the patient is over age 38, has had previous unsuccessful cycles with SET, or only has lower-quality embryos available. Transferring more embryos can increase the chance of pregnancy in some situations. However, this method also raises the likelihood of twins, triplets, or higher-order multiples. Multiple pregnancies are associated with increased maternal and infant risks, including higher rates of miscarriage, preterm birth, and postpartum hemorrhage. Multiple embryo transfer can also be helpful if cost is a concern.
Factors that guide decision-making
Several factors influence whether SET or MET is recommended. Age, embryo quality, and medical history all play important roles in this decision. Previous IVF outcomes and genetic testing results should also be considered. While patient preferences are considered, fertility specialists will ultimately recommend the approach that is safest and most effective.
Choosing the right path forward
Single and multiple embryo transfer approaches each offer unique benefits and considerations. Advances in IVF have made SET a safe and effective option for many patients. Careful evaluation helps determine the most appropriate strategy for each individual case. Reducing risks while maintaining strong success rates remains a top priority.
