IVF with frozen embryos

Last updated date: 17-Aug-2023

Originally Written in English

IVF with Frozen Embryos


Preparing for your frozen embryo transfer can bring uncertainty, worry, and fear to couples who have had failed IVF cycles. Bringing new life and starting a family is a dream that many couples have, but fertility is not always an easy path. Fortunately, for people who have already had one (or more) In-Vitro Fertilization (IVF) cycles and have frozen embryos left over, previous attempts at embryo transfers or IVF can provide a large number of embryos for future attempts.


What is a Frozen Embryo Transfer?

Frozen Embryo Transfer

FET is a cycle in which a frozen embryo from a previous fresh IVF cycle is thawed and transferred back into a woman's uterus. This means that you will not have to go through another cycle of hormone stimulation and egg collection. Frozen embryo cycles can be done naturally or with hormone preparation or ovulation induction.

We may be able to create more than one embryo during an IVF cycle at times. We typically advise transferring one and freezing the others. This is due to the serious risks associated with multiple pregnancies if more than one embryo is transferred at a time.

You will take different injections and oral medications every three days for two to three weeks after your fertility specialist or doctor has cleared you to start a cycle following menstruation. Depending on your specific situation, your fertility specialist and doctor may recommend additional medications.


Benefits of a frozen embryo transfer

Embryo freezing increases your chances of getting pregnant with each hormone stimulation cycle and egg collection. We can transfer a frozen embryo during a frozen embryo transfer cycle if you do not become pregnant after the first transfer from that cycle.

This means you won't have to go through another cycle of hormone stimulation and egg collection.


Frozen Embryo Transfer Success Rates

Patients aged 35 and under have a 60% pregnancy rate per embryo transfer, whereas women over 40 have a 20% pregnancy rate per embryo transfer. When you decide to have a frozen embryo transfer, it's critical to prepare your uterus for implantation with the right drugs and behaviors.


When is a Frozen Embryo Cycle Recommended?

Frozen Embryo Cycle

When the ovaries are stimulated in a typical IVF or ICSI cycle, they produce multiple eggs for insemination, which often results in the formation of a number of healthy embryos. Because only one (or two) will be transferred to the uterus immediately, the remainder can be frozen 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 developed to a suitable stage or if she is at risk of developing ovarian hyper-stimulation syndrome (OHSS), a woman undergoing IVF treatment may be advised to freeze all of her embryos and not transfer any immediately.

It is also becoming more common for fertility specialists to recommend that all of a patient's embryos be frozen because the more natural environment in the uterus during a later cycle may have a better chance of establishing a pregnancy.

Freezing embryos 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.


How Frozen Embryo Transfer Works With IVF?

 Frozen Embryo Transfer

FET is one method for avoiding desynchronization. Delaying embryo transfer until a later cycle allows your hormones to normalize and may increase your chances of pregnancy. Rather than implanting embryos while the body recovers from IVF, embryos are created and frozen. The embryos are thawed and implanted after the body has recovered from the stress of IVF and has returned to a more normal cycle.

Families who want to choose the gender of their child also use this procedure. They may wish to do so for a variety of reasons, including ensuring a balanced representation of the sexes. Embryos are created, biopsied, tested, and frozen during the first cycle. Once the biopsy results are in and the female partner has recovered from her egg retrieval, an embryo transfer will be scheduled.


Types of FET-IVF


Two Types of FET-IVF Cycles: Hormonal and Natural Support

There are two kinds of FET-IVF cycles: Hormonal support cycles and natural cycles. 

  • Hormonally supported FET cycles are more popular with couples because estrogen and progesterone are administered to mimic the body's cycle and thicken your endometrium. Clinics and labs typically prefer this FET cycle because the day of the frozen embryo transfer is easy to control and hormonal support is available for ovulatory problems.
  • The timing of your frozen embryo transfer in Natural FET-IVF cycles is determined by when you ovulate naturally. However, an hCG shot is usually given to ensure ovulation, and progesterone is used for luteal phase support after ovulation and transfer.


How to Prepare for Your FET-IVF 


When preparing for and anticipating the procedure and outcomes of your FET cycle, you must remember that you are in good hands. It's critical to plan ahead of time for what to expect and how to improve your chances of success, so you're off to a good start.

Many doctors recommend various medications and protocols prior to the procedure, so you could be in bed for anywhere from a day to two weeks. You must follow the recommendations of your doctor and fertility specialist. Use the following tricks and tips before your IVF frozen embryo transfer to increase your chances of a successful transfer:

  1. Organize and Take Medications on Time

You will be given progesterone and other supplemental medications to prepare your uterus and other hormonal functions before undergoing a frozen embryo transfer. Ascertain that you have adequate medication levels and that you understand how to take them.

If your doctor recommends bed rest, make sure you have everything you'll need nearby, especially your fertility medications. Plan out what medications you'll be taking each day and make sure you have easy access to everything your doctor prescribed. This will also ensure that you don't forget anything important before the procedure and that you're doing everything you need to do.


    2. Place a Trash Can Next to Your Bed

Before the embryo transfer, there may be a lot of waste and packaging associated with fertility medications. Check that you can easily dispose of any necessary waste without getting out of bed and disrupting your sleep.

Furthermore, having a place nearby to dispose of medicine packages and other waste will help you significantly reduce clutter (and stress levels) while waiting for your frozen embryo transfer. 


    3. Stock Up on Entertainment

Whether you like to read, watch TV, or listen to music, keeping yourself entertained during the procedure is important for a few reasons. For starters, this distracts you from a potentially nerve-racking first experience for many women who have not yet had an embryo transfer. Second, keeping yourself entertained while on bed rest is an excellent opportunity to practice self-love and self-care.

We live in a fast-paced society where hustling is encouraged, but disconnecting and immersing yourself in something you enjoy can leave you feeling revitalized and excited. You can't pour from an empty cup, and self-esteem is an excellent way to avoid burnout. 


    4. Purchase Warm Socks

A "cold" uterus with poor blood flow and circulation can be a cause of infertility, according to Chinese medicine. Having said that, wearing socks certainly can't hurt. Warm socks, while slightly controversial, are a long-standing IVF superstition that many patients adhere to.

For the simplest procedure, slip-on shoes with warm socks are often recommended for the day of your embryo transfer. This will keep your body warm and prevent you from getting cold feet during the embryo transfer process.


   5. Get Plenty of Sleep Before (And After) the Transfer

Ironically, being on bed rest can make getting a good night's sleep more difficult. Sleep and fertility are inextricably linked, so getting enough sleep to support your IVF cycle is critical. If you have trouble falling asleep, you can take melatonin to help you sleep naturally.

When sleeping before your embryo transfer, try to:

  • Keep your bedroom between 60 and 67 degrees Fahrenheit
  • Diffuse lavender in your bedroom or bathroom
  • Avoid caffeine four to six hours before you go to sleep
  • Stop eating two to three hours before you go to sleep
  • Listen to relaxing music 
  • Limit blue light and screen time at least 30 minutes before bed
  • Stretch gently and loosen your muscles before sleeping 


    6. Avoid Extreme Temperatures Against your Abdomen and Uterus.

If you intend to work while on bed rest, get a laptop tray or use some material that will block the heat from your laptop. Because the heat produced by your laptop (and other technology or devices) can be harmful to your uterus and fertility, keep your laptop away from your body while preparing for the procedure.

This rule, however, does not only apply to technology; visiting saunas, hot tubs, or other high-heat activities is not a good idea because these external agents can impact or inhibit your chances of a successful embryo transfer and pregnancy at the end of your IVF cycle.


    7. Prepare and Eat IVF-FET Safe Meals 

To reduce inflammation throughout the body, G.I. tract, and reproductive system, many fertility specialists recommend a high-fat, low-carb diet. This diet also improves hormone function because many female hormones are derived from cholesterol, which is derived from fat.

It is also critical to consume an antioxidant-rich diet prior to embryo transfer, so fresh produce and fruit will be essential.

In general, reproductive endocrinologists recommend warmer foods with high concentrations of omega-3 fatty acids. As you prepare for your frozen embryo transfer, eat foods like: 

  • Warm soups 
  • Whole grains like quinoa, farro, and whole-grain pasta
  • Legumes like beans, lentils and chickpeas
  • Healthy fats like avocado oil, extra-virgin olive oil, walnuts, and seeds
  • Lean proteins like fish and chicken (look for low-mercury fish)
  • Fresh fruits and veggies (Berries, Pineapple)
  • Water with lemon


Foods to AVOID before your frozen embryo transfer

Cold foods are not embryo-transfer friendly, so try to avoid: 

  • Cold beverages like smoothies and sodas
  • Sugar
  • Red meat products
  • Highly processed foods
  • Salt -- season with herbs and spices instead
  • Coffee and tea 


    8. Avoid Endocrine-Disrupting Chemicals (EDC).

It is critical to avoid endocrine-disrupting chemicals during the FET process (EDCs). EDCs disrupt your hormones, reproductive health, and prenatal development, and are generally detrimental to your overall health.

Formaldehyde, Parabens, Benzophenone, Triclosan, BPAs, Phthalates, and Dioxins are examples of EDCs found in everyday household products. Remove all strong chemicals and scented products to reduce disruptions during the embryo transfer and IVF process.

Products to remove include: 

  • Nail polish 
  • Plastics (make sure you're drinking water from a BPA-free water bottle)
  • Nonstick cooking tools
  • Cosmetics with fragrance
  • Soaps and moisturizers with fragrance
  • Meat and dairy
  • Stain-resistant materials

Discuss with your fertility doctor any other chemicals or toxins to which you may be exposed, as well as how to replace or remove them around your frozen embryo transfer.


   9. Plan Logistics Before Your Transfer

The last thing anyone wants to do before their embryo transfer is get stuck in traffic. Before your embryo transfer, ask your fertility doctor and IVF clinic for important FET-IVF logistical information, such as:

  • What you can bring to the appointment (ask if you can bring a camera - trust us, you’ll be happy you did!)
  • How long you can expect to be at the clinic
  • What time you should arrive 
  • What you’ll wear (try to avoid tight pants and remember socks!)
  • Who can go with you
  • How long after the frozen embryo transfer you'll need to wait

This will help to reduce stress, ensure that everything runs smoothly, and make you feel confident and prepared for this exciting procedure!


   10. Pack a Bag the Night Before

Make plans for the next day and pack your bag with anything you might need the night before your frozen embryo transfer, but don't overdo it!

As you pack a bag for your embryo transfer procedure, make sure you include: 

  • Water 
  • Warm socks 
  • Loose pants
  • A camera
  • Books or a journal
  • Earbuds or headphones


Frozen Embryo Transfer process

Frozen Embryo Transfer process

Thawed embryos can be replaced during a natural cycle (without drugs) or in a hormone-supplemented cycle. Your fertility specialist will be able to advise you on the best treatment for you based on your medical history and age.

The procedure for transferring frozen embryos is the same as for transferring embryos in a fresh cycle. Once the embryo has thawed, an ultrasound-guided catheter containing the embryo is gently inserted into the cervical channel and uterine cavity. The catheter is then removed and the embryo is checked to ensure that it has been transferred. After the transfer, you can resume your normal activities, knowing that the embryo is safe within the uterus. A pregnancy test is usually scheduled twelve to fourteen days after embryo transfer. It is best to avoid strenuous activity and heavy lifting during this time.


Spare embryos

Most people who have IVF or ICSI treatment will have embryos left over for the future, either if the treatment fails or for a sibling. Depending on their quality, spare embryos from your IVF treatment can be frozen for future use. This would necessitate a frozen embryo transfer, also known as a "FET" cycle. Embryos can be kept for up to ten years for future use.


Frozen Embryo Transfer vs. Fresh Embryo Transfer

Frozen Embryo Transfer

Fresh embryo transfer takes place during the same cycle as IVF. In the lab, the eggs are extracted and fertilized. The embryos are allowed to develop before being transferred back into the woman's uterus 5-6 days later. A frozen embryo transfer is a unique procedure. A woman has IVF, her eggs are retrieved and fertilized in the lab, and the resulting embryos are allowed to develop in this type of cycle.

Instead of being transferred back into her uterus on day 5 or 6, the embryos are frozen. Preimplantation genetic testing can be done on embryos before they are frozen to screen for common chromosomal diseases and to determine the embryo's gender. The transfer would take place once these results were received.


What is the Success Rate of a FET in IVF?


Freezing techniques, such as the vitrification method, have advanced significantly in recent years to mimic natural conception, resulting in higher pregnancy and live birth rates, lower miscarriage rates, and healthier babies. Older slow freezing technology produced few viable embryos, but Aspire's advanced vitrification method significantly reduces loss rates.


Risks of Frozen Embryo Transfer

Risks of Frozen Embryo Transfer

A frozen embryo transfer cycle is far less risky than a full IVF cycle. Ovarian hyperstimulation syndrome (OHSS) is one of the most serious risks of using IVF (and fertility drugs). However, because ovarian stimulating drugs are not used in a FET cycle, OHSS is not a concern. 

Many embryos will survive the freeze-thaw cycle thanks to cryopreservation. If an embryo's Preimplantation Genetic Testing (PGT) results are indeterminate (it is unclear whether the embryo is normal or not), it can be biopsied again. This reduces the success rate slightly, but not significantly.

When embryos are frozen, thawed and re-biopsied, and/or refrozen, there is a risk that they will be lost or have a lower success rate when thawed for use. However, this does not always imply that a fresh transfer is the best option.

Some research has suggested that babies born from frozen embryo transfers may be large for gestational age. However, a meta-analysis discovered that frozen embryo transfers may result in healthier pregnancies and babies than fresh embryo transfers. The researchers discovered that babies born from frozen embryo transfer had a lower risk of preterm birth, stillbirth, and low birth weight.

Another study compared the chances of having a birth defect in children born through fresh IVF transfers, frozen embryo transfers, and naturally conceived children. The study discovered that fresh IVF transfers were three times more likely to result in birth defects than naturally conceived children. However, with frozen embryo transfer, there was no increased risk (perhaps because these frozen embryos could have been tested with PGT). The overall risk of birth defects remained extremely low.



If you are having IVF and have one or more frozen embryos, you may want to use them in a future cycle. This fact sheet explains how the frozen embryo transfer procedure works.