A single in vitro fertilization (IVF) cycle can create more embryos than are safe to transfer to the mother’s uterus in that initial cycle. Patients then have the option to cryopreserve, or freeze, excess embryos. Embryo cryopreservation has afforded a highly proven and reliable option for many years. The main reason is that embryos can be frozen at different stages of development for subsequent pregnancy attempts. Further, when patients wish to proceed with using their previously frozen embryos, the frozen embryo transfer (FET) is less complicated physically and financially than for an initial IVF cycle.
Generally, FET can cost significantly less than an IVF cycle using fresh embryos, in part because ovulation-inducing medications are not necessary. Depending on a woman’s overall health, her cause of infertility, and how much time has passed since the last IVF cycle, additional assessment testing may be required before FET. Of course, each patient should also discuss with the medical team how many thawed embryos should be transferred in order to maximize the odds of pregnancy while minimizing the chance of multiple births, which are much riskier to both mother and child.
The Society for Assisted Reproductive Technology has specific guidelines for the maximum number of embryos to transfer. On the morning of the transfer, the lab team thaws a select number of embryos. Most – about 70 percent – usually survive the thaw. Even if all of the cells of an embryo do not survive the thaw, the embryo still has a chance to produce a pregnancy. The transfer procedure is similar to that performed in fresh-embryo transfer. The woman next undergoes a blood test about 12 days later to determine if the transfer has resulted in a pregnancy.
Fertility Success Rates
For more information on ongoing pregnancy rates.