After a successful IVF cycle, frozen embryos give many fertility patients a backup plan and the possibility to expand their families. After fertility medicines and ovarian stimulation, egg harvesting, and laboratory fertilisation, a patient undergoing IVF may discover that they have more viable embryos than they need to transfer in one cycle. In most circumstances, your doctor will choose one (or maybe two) high-quality embryos for a fresh one transfer to limit the possibility of a dangerous multiple pregnancy. The remaining can be frozen and kept for future use. Call and book your appointment with world infertility & IVF centre Delhi.
In certain cases, all of the embryos from a cycle may be stored so that the woman’s body can heal from the stressful IVF procedure before undertaking a FET in a month or two. If fresh embryo transfers have previously failed, FET can sometimes improve the odds of implantation, especially when combined with advanced testing such as Endometrial Receptivity Analysis to determine a woman’s best implantation window.
Whatever your reasons for pursuing FET, the first question you’re probably going to ask is whether they have a high success rate.
What frozen embryo transfer?
This involves thawing one or more embryos (preserved during a previous treatment cycle) and transferring that embryo to the uterus in an attempt to generate a pregnancy.
When is a frozen embryo cycle recommended?
When the ovaries are stimulated in a typical IVF or ICSI cycle, they generate many eggs for insemination, which often results in the formation of a large number of viable embryos. Because only one (or two) will be transferred to the uterus immediately, the remainder can be preserved for use in a subsequent IVF cycle if the first transfer does not result in a pregnancy, or to create a sibling at a later time.
If the uterine lining has not matured to an appropriate stage or if she is at danger of developing ovarian hyper-stimulation syndrome, a woman undergoing IVF therapy may be recommended to freeze all of her embryos and not transfer them immediately (OHSS).
This is also an option for a woman who wants to delay pregnancy until her late 30s or early 40s but realizes she may not have suitable eggs by then.
What are the rates of success for FET?
The success rate of a pregnancy is determined by a number of factors, including the woman’s age.
If cells are damaged, some embryos (or all) will not survive the freezing and thawing process. If they are frozen by ‘vitrification’ at the blastocyst stage, they have a survival rate of more than 90%. (5-6 days after fertilization). If they are frozen at an earlier stage by ‘slow freezing,’ they will survive the freezing and thawing process in about 80% of the cases.
When an embryo that has been vitrified at the blastocyst stage is thawed and transferred, it has roughly the same success rate as a fresh embryo.
There is no evidence of causing more miscarriages or abnormalities.
What factors influence success rates?
This was a difficult question to answer nearly 30 years ago, when the first child was born from a frozen embryo transfer. FET success rates were inconsistent until recently.
This was due to two major factors:
Quality: With today’s advanced reproductive labs, procedures, and technology, embryos can be developed in the laboratory until they reach the blastocyst stage, which takes around five days. Because embryos that survive to the blastocyst stage are generally stronger and healthier, five or six-day transfers have a far better chance of resulting in pregnancy. This means that doctors can now successfully transfer a single blastocyst. It used to be difficult to keep them alive and healthy in the lab for more than three days. As a result, it was typical to transfer numerous embryos at once, which frequently resulted in just the lowest-quality embryos remaining. These low-quality 3-day-old embryos had a substantially decreased chance of surviving cryopreservation and subsequent thawing. Even if they survived, their odds of implantation were slim. Today, it is not uncommon to have three or more high-quality blastocysts ready to freeze from a single IVF session.
Techniques for Freezing: Using cryopreservation to freeze embryos used to be a relatively dangerous operation, with the chances of it surviving both the freezing and thawing processes being uncertain. This was due to the fact that the freezing procedure used was somewhat sluggish, and the embryo’s delicate cells might be easily destroyed by forming ice crystals. A new, improved freezing technology known as vitrification was created about a decade ago. Vitrification is a “flash freezing” procedure in which they are quickly chilled to freezing temperatures. Special advanced medium is also utilized to assist in safeguarding the cells, with cryoprotectants preventing ice crystals and allowing the embryo’s cells to freeze smoothly. With these advancements, frozen embryos now have substantially greater survival rates (over 95 percent) when thawed, as well as much higher conception rates.
What is the most recent study on the success rates of frozen embryos?
When it comes to frozen embryo transfers, recent research has given us a lot of cause to be optimistic. The general consensus is that FET success rates are at least as high as fresh embryo transfer success rates in the majority of situations. FET success rates can be substantially greater than fresh embryo transfers for some women. According to a study released earlier this year by Stanford University researchers, frozen embryo transfers were 73% more likely to result in an ongoing pregnancy than fresh transfers in women over 35 with high progesterone levels.
As always, we must remember that each patient is unique, with a plethora of individual circumstances that can influence her chances of getting pregnant from each transfer, fresh or frozen. If you’re unsure if FET is the correct choice for you, talk to your fertility treatment doctor. Whether you are considering a “freeze all” cycle or simply want to learn more about preserving it from a new cycle, your doctor can help you devise a strategy that will give you the best chance of success in your specific situation.