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When it comes to fertility treatments, the technique of cryopreservation - or the freezing of embryos - has proved to be a game changer in the path to parenthood. It is the practice of storing embryos at a temperature of -196°C in liquid nitrogen. Fortunately, more than 95% of embryos can be effectively frozen and thawed for the hopeful parents to have other chances for conception.
This blog will explain the complex process of Frozen Embryo Transfer, or FET, and why it is becoming the choice of many couples going for IVF treatment.
Synopsis
What is Frozen Embryo Transfer?
Frozen Embryo Transfer (FET) is a technique that comes under IVF where the embryos that were initially frozen are thawed and then the frozen embryo is transferred into the uterus. The procedure can be performed in several ways depending on the patient’s specific circumstances.
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Hormone Replacement Cycle (HRC): In this method, a woman intending to freeze her embryo is prescribed estrogen tablets to prepare the lining of the uterus to host the embryo and then progesterone therapy to prepare the uterus for the embryo. This procedure assists in the preparation of the uterine ecosystem to accommodate the embryo.
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Natural Cycle: Otherwise, in the natural cycle, the woman is observed until ovulation happens on its own. The embryo is then inserted into the uterus three to five days after ovulation to resemble normal conception.
An IVF specialist will determine the suitability of the procedure. Make sure to discuss all the aspects of these procedures in your consultation.
Success Rates of IVF
Multiple research studies have shown that there is no massive disparity in live birth rates (LBR) between FET and fresh embryo transfers. Remarkably, some studies even pose the idea that FET may have a slightly better LBR than fresh transfers. This is one reason behind IVF pregnancy is gaining popularity.
The Three Stages of IVF
Before diving deeper into the advantages of freezing embryos, it’s essential to understand the three stages of In Vitro Fertilization (IVF).
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Controlled Ovarian Hyperstimulation (COH): This phase stimulates the ovaries with daily injections. This induces the production of multiple eggs. Thus, it enhances the likelihood of successful fertilisation.
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Egg Collection: When the eggs reach maturity, they are collected from the ovaries. It follows a minor surgery under sedation.
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Embryo Transfer: After fertilisation in the laboratory, embryos are implanted immediately or cryopreserved into the uterus for later use.
Advantages of IVF or Freezing Embryos
Freezing embryos offers several significant benefits. These advantages make this procedure a preferred strategy in many IVF treatments.
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Reducing the Risk of OHSS: Ovarian Hyperstimulation Syndrome (OHSS) is a possible side effect of COH. The ovaries can become enlarged and uncomfortable. Embryo freezing gives time to the ovaries to recover before the transfer. This decreases the likelihood of late OHSS.
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Planning for Future Pregnancies: Couples who have their first baby with IVF can store extra embryos for later use. This eliminates the necessity for multiple egg retrievals. If you want to have multiple children, this option is for you.
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Preserving Fertility Before Cancer Treatment: Women undergoing cancer therapies can freeze either eggs or embryos beforehand. This can safeguard their ability to conceive in the future. Following their recovery, they can use their frozen embryos to begin a family.
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Social Freezing: An option for women who want to postpone pregnancy. The reason can be anything - be it your career commitments or not feeling ready. You can retain your fertility by freezing your eggs or embryos. You will have the time to strategise and start a family at a more opportune time.
Does the Duration of Storage Affect Embryo Viability?
Medical experts often come across a common worry. This is if the stored embryos can get affected as time moves on. Of course, eventually, that can impact one’s chance of a successful pregnancy. Studies have shown that the duration of embryo storage does not have a notable effect on clinical pregnancy rates, miscarriage rates, implantation rates, or live birth rates. This sense of security has resulted in the extensive implementation of the "freeze-all" approach. This is where all viable embryos are frozen for future use.
Cryopreservation and Frozen Embryo Transfer (FET) offer numerous advantages in the journey toward parenthood. Whether it's reducing the risk of OHSS, planning for future pregnancies, preserving fertility before cancer treatment, or opting for social freezing, the ability to freeze and store embryos has transformed the landscape of IVF.
The process is not only safe but also effective, with high survival rates of embryos post-thawing. As IVF technology continues to evolve, the freeze-all strategy is becoming more commonplace, offering hopeful parents more control and flexibility in their path to parenthood.
FAQ's
Embryos can be stored for many years without notably impacting their viability. Research has shown that the duration of storage does not significantly affect clinical pregnancy rates, miscarriage rates, or live birth rates.
In a fresh embryo transfer, the embryo is transferred to the uterus shortly after fertilisation, typically within a few days. In contrast, a frozen embryo transfer (FET) involves thawing a previously frozen embryo and transferring it to the uterus later, often during a different menstrual cycle.
Studies have shown no significant difference in success rates between FET and fresh embryo transfers. In some cases, FET offers a slightly higher live birth rate, making it a viable option for many couples.
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