Fresh vs. Frozen Embryo Transfer... Choices
When all seams perfect and linear here comes the question, "Fresh should always be better", Right...? Well, when it comes to embryo transfers, the dogma has changed and what was "true" once, may have been replaced with a difference answer.
Below we will review the options and the choices for an embryo transfer.
There are many decisions to make on your journey to becoming a parent. Which infertility clinic is a good fit? What treatments are you willing to undergo? Is it better to transfer fresh or frozen embryos for IVF (In Vitro Fertilization)? Most importantly your treatment team can help you navigate through the choices that are more appropriate for you.
A Fresh Perspective All embryos start out fresh. In a woman’s initial IVF cycle, she takes medication to first “quiet” the ovaries, making them more sensitive and synchronized with medication to stimulate them to produce extra eggs. After the eggs have been retrieved through a minor surgical procedure, they are fertilized. The resulting embryos grow in a state of the art special incubator until they are ready to be transferred to the uterus. In most cases, one embryo is selected for transfer and the remaining embryos are frozen. Fresh cycles were, for decades, the gold standard…until a decade ago when rapid advancements in freezing and cryopreservation methods improved the outcome of FETs.
Back in the Day First, a little history on frozen embryo transfer (FET). Embryos were initially frozen very slow method which causes intracellular razor sharp ice crystals to form; unfortunately, these ice crystals can permanently damage the embryos during the thaw/warming steps. Many damaged embryos didn’t survive these slow freezing process, and those that did had very low potential for successful implantation due to the damage done. However, in the last several years we’ve seen a dramatic increase in the quality of frozen embryos due to the introduction of a much rapid freeing method, called vitrification. Vitrification is an ultra-rapid freezing method that freezes the embryo approximately 60,000 times faster than the older method of freezing. This process takes ice formation out of the equation, resulting in a significant increase in viable embryos with successful implantation and pregnancy potential equal to fresh embryos.
Timing is Everything Also, one of the major reasons we see markedly higher FET success rates now than several years ago is that the timing of when the embryo is frozen has changed. It’s been shown that freezing at a later-stage of embryo development called blastocyst that is attained between days 5 and 6 has a better outcome than freezing early-stage called cleaved embryos (day 2-3). In many cases embryos that don’t successfully develop to the expanded blastocyst stage have chromosomally abnormalities (such as abnormal number of chromosomes, called aneuploidy, such as down syndrome) and don’t result in healthy babies. An additional benefit of FET using embryos at the blastocyst stage is that fewer embryos – because we’re able to determine which are most viable – need to be transferred. Transferring one embryo at a time , means we can minimize the chance of a multiple pregnancy, along with the inherent risks to both mom and baby.
Fresh or Frozen? At this point, the scientific studies show that successful outcomes using FET are similar to those of fresh embryo transfers. However, there are some key benefits that make FET appealing:
· Because you underwent ovarian stimulation and egg retrieval for your fresh cycle, you won’t have to go through it again. The medications necessary to prepare your body for FET have fewer potential side effects and take less of a toll on your body.
· Many patients report that FET cycles are not nearly as stressful as fresh cycles since they already know they have viable embryos.
· It’s easier to schedule and plan for FET cycles than fresh cycles.
If you’d like to learn more about how fresh and/or frozen embryo transfers and IVF may benefit you, schedule an appointment with Dr De Pinho and discuss your options.
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