Fertility Treatments


FET (frozen embryo transfer) is a technique used in IVF (in vitro fertilisation). Embryos may be produced in excess of what is required during IVF. The doctor may then give you the option of donating the extra embryos to a research facility or freezing them for later use.


The technological era has been fantastic for countless reasons, one of which is healthcare specialists being able to help the people experiencing fertility problems with the gift of a child. The fertility doctor first examines your health and the root cause of fertility problems. 

In some cases, either partner may require fertility treatment. But sometimes, both of them need a suitable treatment combination together. 

The fertility doctors usually perform multiple treatments, including prescribed medications to help you with ovulation and hormones. Your doctor may sometimes combine these medications with minimally-invasive surgical procedures. To have a baby, the doctor may recommend several procedures with the help of assisted reproductive technology (ART), which includes medical procedures to make the process of eggs being fertilised by the sperm a little easier. These procedures will also help with the embryo implanting your uterine lining. 

There are several fertility treatments available to help you conceive a baby. The most common ones are:

  • IUI or Intrauterine Insemination: Intrauterine insemination or IUI is a medical procedure in which the doctor places sperm into the uterus of an ovulating woman. The IUI procedure is conducted in concurrence with ovulation-stimulating medications. The doctor will either use the husband’s or a donor’s sperm after taking due consent from the couple.
  • IVF or In Vitro Fertilisation: IVF or in vitro fertilisation is a complicated sequence of medical procedures aimed at helping people who encounter genetic or fertility issues and helping them through child conception.

If you have had problems conceiving a child naturally, there may be an infertility issue. In that case, you may want to get in touch with the fertility experts at Siya Health. We’ll help you figure out which fertility treatment will be the most suitable for you.

What Is FET?

FET, or frozen embryo transfer, is a part of IVF or in vitro fertilisation. During the IVF, more than required embryos may be produced. That’s when the doctor may give you a choice to either donate the extra embryos to a research facility  or freeze them for future use (if you want another child or your first IVF attempt is unsuccessful). 

During the embryo transfer procedure, the doctor will thaw (gently warm) the embryos and slowly transfer them to the patient’s uterus with the help of a thin, flexible and long tube called a catheter. Suppose you freeze the extra embryos produced during the first or previous IVF cycle. In that case, the IVF process won’t be as stressful and an emotional rollercoaster as the initial in vitro fertilisation attempt. 

After your embryologist or fertility specialist clears you post menstruation, you will be given a few injections and oral medicines every three days for 2-3 weeks to ensure that your uterine lining is thick enough for the forthcoming procedure. The medications and injections will be prescribed as per your unique initial diagnosis and situation.

How Does It Work?

Your estrogen levels are usually at their highest right before ovulation, during the menstrual cycle. The surge in estrogen is the trigger behind ovulation, which results in the ovaries starting progesterone production. Progesterone is the hormone behind the development of the uterine lining. 

For you to get pregnant, the eggs fertilised with sperm need to latch on to the endometrial lining and start growing. Since progesterone production results from ovulation, ideally, your endometrial lining develops at the right pace for nurturing the fertilised eggs. Simply put, the ideal environment for fertilised egg implantation is achieved by perfect sync between progesterone surge and development of endometrial lining. 

But during in vitro fertilisation, medications stimulate your ovaries, which takes the peak of estrogen levels. But this higher than usual estrogen surge results in the production of progesterone. But sometimes, the progesterone hormone may surge too early in the stage, and your endometrial lining has developed too quickly. In that case, the creation of endometrial lining may not be in sync with the embryos, which means that the embryos may not latch on the lining successfully, and you may not get pregnant. That’s why the doctors prescribe medications to the patient in order to suppress the production of progesterone. But there’s no guarantee that these medications work for everyone. So you may still end up with a desynchronised cycle. 

FET or frozen embryo transfer is considered an excellent way to prevent desynchronisation. With the help of FET, you’ll be able to freeze your embryos. You can delay the embryo transfer until you have the next cycle and the hormones have normalised. Then, you can place the embryos in the uterus, giving them a better chance at implantation. Through this process, the chances of you getting pregnant will be higher. 

The embryos are created and frozen till the time your body recovers from in vitro fertilisation. After your body has returned to the normal cycle after recovering from IVF, the doctor will thaw the frozen embryos and place them into your uterus for implantation. The procedure is also beneficial for those couples looking for a child of a particular gender for any personal reason. The embryos are created, put through biopsy (to check for any contamination and disease), tested, and then frozen during the first cycle. The doctor will transfer the thawed embryos later on a later date when the biopsy has shown no issues, and the patient has recovered from the egg retrieval process.

Fresh Or Frozen, Which One Is Better?

The transfer will be scheduled and conducted in the same IVF cycle when it comes to fresh embryos. After the eggs are retrieved from the patient and fertilised with the sperm, the resulting embryos will be left to develop in the lab. Then, they will be placed back into the patient’s uterus about 5 or 6 days after they were collected. 

But the process is a little different when it comes to FET or frozen embryo transfer. First off, like the fresh process, the woman’s eggs are retrieved and then fertilised in the fertility lab. Then, the embryos are left to develop. But then, on the 5th or 6th day, instead of placing the developed embryos inside the patient’s uterus, they are frozen to be used later. Before freezing them, the doctor may decide to perform preimplantation genetic testing, which will help them check if there is any disease and also determine the gender of the embryo. The transfer will be done only after the results come good. 

Although FET was a bit strange in the earlier days, more and more people going through IVF are opting for this technique. That’s because the benefits provided by modern artificial reproductive techniques can be further optimised with the help of cryopreserved or frozen embryos. As a result, it can increase the probability of you getting pregnant and safeguard your pregnancy. 

Contrary to what people think, frozen embryo transfer is quite a simple process of cryopreservation of the developed embryos to be used later. The embryos can remain safe and secure and maintain their stability in the cryopreserved state for even years. Then, when it comes to the fresh process, the doctor will transfer the embryo back to the uterus as soon as it is ready for implantation. 

Although fresh transfer used to be more popular a while ago, thanks to technological advancements, more and more people are now opting for FET because it provides relatively higher pregnancy rates.

How Does FET Relate To The Blastocyst Implementation?

Blastocyst embryo transfer is a special technique in IVF or in vitro fertilisation, in which an embryo in its blastocyst stage is transferred into the patient’s uterus. 

The blastocyst stage is around the 5th day after the fertilisation. The embryos move from the fallopian tubes to the uterus during the blastocyst stage in a natural pregnancy. Once the blastocyst embryo is in the uterus, a process known as implantation starts, in which the embryo latches onto the uterine lining. 

You can slightly delay the implantation after frozen blastocyst transfer when compared to the fresh blastocyst transfer. That’s why the process for blastocyst in the frozen state is sometimes called delayed implantation or “late implantation”. 

But the process, when it comes to frozen embryo transfer, is not different enough to delay or change the timing of your blood pregnancy test. Just a few days (1 to 3 days) after FET, you’ll have the start of hatching and implantation in case of frozen blastocyst transfer. 

The doctor may conduct a sensitive blood evaluation for HCG around nine days after blastocyst transfer to detect early pregnancy. 

If the urine home pregnancy test kit is of a sensitive kind, you may be able to detect your pregnancy about 12 days after the blastocyst transfer.

Why Should You Choose The FET Procedure?

First off, FET provides a patient with a chance to recover from the egg retrieval so that the implantation goes well. Secondly, it will give the doctors a chance to match the sync between the development of the embryo and uterus, ensuring a higher chance of pregnancy. The third reason for opting for FET is that it gives the doctors a chance to check and analyse the embryos for any diseases, abnormalities and contaminations before they are transferred into the uterus. 

Here are a few other reasons to opt for frozen embryo transfer:

  • Extra embryos

In the case of IVF, you may end up with several embryos. But the experts recommend implanting just one or two embryos at a time. In that case, you may opt to have them frozen. Then, if your initial IVF attempt fails, you will have backup embryos to go for another shot. Implanting more than one or two embryos simultaneously may result in multiple births, which is not good for the baby. It can cause the babies to be born premature, underweight and have other issues as well. So you may opt for elective single embryo transfer or ESET, in which one embryo will be implanted into your uterus, and the others will be frozen. 

  • Aspire another child

Let’s say you have a child born with IVF. Then if you freeze your extra embryos, it will be easier for you to become pregnant again with the help of a frozen embryo transfer. Cryopreserved embryos can maintain their stability for years, which gives you a chance to be absolutely sure about your decision about another child. On the other hand, going for another child via IVF with fresh embryos will be relatively more expensive. So FET is the way to go.

  • Genetic screening

Genetic screening or preimplantation genetic testing is an integral part of artificial reproductive techniques. It is possible to implant the frozen embryos right after thawing them, but the doctors recommend against it. If you have opted or the doctor has recommended the frozen embryo transfer, you will have a chance to have your embryos tested through preimplantation genetic screening and preimplantation genetic diagnosis. These tests will be able to detect any diseases, abnormalities, contamination, etc., with the help of a biopsy between days 3 and 5 after the fertilisation. So with the help of FET, you will be able to wait for the results to come back and implant the embryos only if they are good.

  • To avoid OHSS

OHSS or ovarian hyperstimulation syndrome is a condition caused by fertility medications, which in severe cases may lead to a loss of fertility or death (in the worst cases). If the doctor detects OHSS before fresh embryo transfer, they may stop the process and recommend frozen embryo transfer. In that case, all of your embryos will be frozen preserved. Going further with your pregnancy even after the detection of OHSS may aggravate the condition, and the recovery will be more difficult. Your IVF will be taken ahead once you have entirely recovered from the OHSS. 

  • Cancellation of fresh embryo transfer

Sometimes, the doctor may cancel the implantation process right before embryo transfer because you may get affected with the flu or another illness between egg retrieval and fertilisation and embryo transfer. The doctor will examine the condition of your endometrial lining with the help of an ultrasound. If the situation is not good, you’ll have to go for a frozen embryo transfer. In that case, the doctor will recommend FET and implant the embryos after you are recovered. So the doctor will schedule a FET-IVF at a later date after the recovery. 

  • Embryo donor

If you have extra embryos, you may opt to go for FET or frozen embryo transfer to ensure that you can use them if the IVF attempt is not successful or you are looking for another child. Also, if you are looking to have a child with the help of an embryo donor, the procedure will be done with the help of frozen embryo transfer. 

The reason for going with the frozen embryo transfer can be any of the above. It can either be an elective procedure or maybe mandatorily required to ensure a smooth experience. It can also help you increase the chances of pregnancy.

What To Expect From The FET Procedure?

FET-IVF cycles can be of two types, i.e. natural cycle and hormonal support cycle. The couples most commonly suggested by a doctor is a  hormonal support cycle for FET-IVF for two reasons. First, you’ll be able to easily control the day you have to transfer the embryos. Then, thanks to hormonal support, you’ll be able to prevent any ovulatory issues. If you want the embryo transfer procedure performed on a particular date, FET-IVF using a hormonal support cycle will suit you. With the help of this cycle, you’ll be able to manipulate the day of progesterone start. But left to nature, you’ll not be able to predict the timeline. 

  • FET-IVF With Hormonal Support Cycle

Like the traditional IVF cycle, FET-IVF with hormonal support will start around the end of the previous menstrual cycle. First, you’ll be given injectable medications to shut the reproductive cycle temporarily. After you have your period, the doctor may go for bloodwork and ultrasound to ensure everything is ok. Then, your estrogen supplementation will be given for about two weeks to ensure a healthy endometrial lining. After two weeks of estrogen, progesterone support via oil injections will be started with vaginal suppositories. The embryo will be transferred based on the start of progesterone, and the stage embryo was cryopreserved in. 

  • FET Natural Cycle

No medications and supplements are used in the FET natural cycle. Instead, the transfer of embryos and other processes are completed according to the natural timeline. But still, the embryo transfer must be done at a particular time, particularly a certain number of days after the ovulation. Since timing is everything, the cycle will have to be carefully monitored either with the help of an ovulation predictor kit at home or with the help of bloodwork and ultrasound at the clinic. It would be best to visit the doctor since the ovulation predictor kit may not be as reliable. Progesterone will be started, and transfer will be scheduled as soon as ovulation is detected. 

The doctor will assess your situation and then determine, after having a consultation with you, to decide whether you will have your IVF with FET hormonal support cycle or FET natural cycle.

What Are The Possible Risks?

Although there are some complications in every medical procedure, the risk will be slightly lower in frozen embryo transfer than in the full IVF cycle with fresh embryo transfer. For example, one of the most significant risks associated with a full-cycle IVF with fertility drugs is the OHSS or ovarian hyperstimulation syndrome. But since the doctor conducts preimplantation genetic screening and doesn’t use any ovarian stimulation drugs in FET, you don’t need to worry about OHSS. 

Most embryos will survive after being cryopreserved and going through freeze and thaw. Then, they’ll go under PGT, and if it comes out indeterminate, the testing will be performed again. But the re-testing may bring down the success rate of in vitro fertilisation. 

Babies conceived through IVF with frozen embryo transfer may be too large in morphology for the gestational age (the period between conception and birth). But experts have found through meta-analysis that the babies through FET-IVF are born relatively healthier than the babies born through fresh embryo IVF. FET-IVF are also less at risk for premature birth and underweight. 

Also, since the doctors conduct diagnostic tests on frozen embryos, they will be able to determine if there is any illness, abnormalities, defects, contamination, etc., present in them. By doing so, the babies born through FET will be less at risk for any diseases or congenital disabilities.

What If The Procedure Fails?

If your frozen embryo transfer assisted IVF fails for some reason, the doctor would first analyse every aspect of your failed attempt. That will be done to gain some perspective into the issue regarding the failure. They will see if there is an issue with ovarian stimulation, egg retrieval, sperm retrieval, fertilisation, embryo development, embryo transfer, differed implantation window or something else. Then, they will analyse and review the pictures of your embryos and other aspects of your cell stages, fragmentation, etc., to come up with a new plan for another FET-IVF cycle. 

Issues determined during the analysis of the failed IVF attempt may not always be fixed. But the doctor will discuss the situation with you to explain the next course of action, second attempt, and success rate. It will help you and your doctor prevent the same issue next time you try a FET-IVF cycle.


FET or frozen embryo transfer is a part of the in vitro fertilisation cycle, in which extra embryos are frozen for further attempts at the IVF cycle. The doctor will thaw and transfer the frozen embryos during the implantation in the uterus. The frozen embryos will either be the female partners’ or from a donor. 

If you have experienced failure during an IVF cycle, trying new technologies can be a bit jarring and fill you with anxiety. Fertility is not always as straightforward as you’d imagine. But with the help of frozen embryo transfer IVF, you’d be able to prevent some of the issues of standard IVF. 

Preparation done by the doctor or fertility specialist is the key to successful FET-IVF treatments. So you may want to get in touch with the best fertility doctors. 

If you want more info about frozen embryo transfers and FET-IVF, please consult the Fertility experts at Siya Health, or call our Siya Fertility Counsellor today.

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Dr. Dipesh Sorathiya

M.S. (Obs & Gyn)
DIP. in Gynec Endoscopy (CICE)

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