Embryo Transfer: What It Is, What to Expect, The Different Types, and More

Fast Facts About Embryo Transfers:

• An embryo transfer is the final stage in the In Vitro Fertilization (IVF) process where the fertilized egg—now an embryo—is placed in the woman’s uterus.
• The embryo is loaded into a catheter, which is passed through the vagina and cervix and into the uterus where it is deposited.
• This generally takes place between 3 and 5 days after egg retrieval if having a fresh transfer and anywhere from 4 weeks to years later if doing a frozen transfer.
• There are many different types of embryo transfers: fresh, frozen, cleavage (day 3), blastocyst (day 5), single, and multiple embryo transfers.
• Today’s standard practice is to transfer one embryo (occasionally two) embryo(s) at a time.  This minimizes the chance of multiples while maintaining the same cumulative live birth rates (per retrieval) from an IVF cycle. Any remaining embryos from the IVF cycle are either frozen (if the first transfer is with a fresh embryo) or remain frozen (if the first transfer is a frozen transfer – also called a freeze-all cycle).
• The cost of fresh embryo transfer is usually included as part of the base cost of an IVF cycle. Frozen Embryo Transfers (FETs) are rarely included in this price and cost an additional $4-5,000 on average across the USA though the price varies widely by clinic.

What is an Embryo Transfer?

An embryo transfer is the last stage in the IVF process, where the fertilized egg that has been left to grow for several days is placed in the woman’s uterus where it will hopefully implant, become a fetus, and result in the birth of a healthy child.

The embryo transfer procedure is done by loading the IVF embryo into a catheter, which is then passed through the woman’s vagina and cervix, and deposited in the uterus.  Anesthesia is usually not necessary, but valium may be used.

Types of Embryo Transfer:

There are many “types” of embryo transfers though the basic principle remains the same.

Fresh Embryo Transfer

Just as the term implies, a fresh embryo transfer is the transfer of (an) embryo(s) that has not been frozen.

Frozen Embryo Transfer (FET)

A Frozen Embryo Transfer is a cycle in which frozen embryos from a previous IVF or donor egg cycle are thawed and then transferred into a woman’s uterus.

A frozen embryo transfer may be done for a number of reasons:

Medically Advised Due to Uterine Receptivity: During an IVF cycle, a woman is in a state of controlled ovarian hyperstimulation, which adds a good deal of physiological stress to the woman’s body.  In some cases, the woman’s body is unable to simultaneously prepare a beautiful “home” for the embryos to be transferred. If the woman has ovarian hyperstimulation syndrome or has elevated progesterone or estrogen levels or has a lining under 7mm at the time of trigger, it may be advised to do a “freeze all cycle,” followed by a FET.  This allows the intended mother to wait until the uterus/endometrium is more receptive and implantation more likely.

A Second Embryo Transfer: In a conventional IVF cycle, it is common for 10-15 eggs to be produced through controlled hyperstimulation, which results in a number of high-quality embryos available for transfer. Today’s standard practice is to transfer one (sometimes two) embryo into the woman’s uterus and freeze all remaining embryos to increase the chance of future pregnancy (should the couple want to continue expanding their family after giving birth or if the first transfer fails).

Easier to plan: Because there are times when it is medically advised to convert a fresh cycle to a freeze-all cycle with an FET, many, particularly travel clients, find it much easier to plan in advance for a frozen transfer as they are rarely ever canceled, can be easily planned, and offer comparable success rates as a fresh transfer.

Cleavage (Day 3) Stage Embryo Transfer:

Cleavage stage embryos are called such because the cells in the embryo are dividing (or cleaving), but the embryo itself is not growing in size. This stage is usually reached around day three, but may happen on day two or four.  They are often referred to simply as “day three embryos.”

Some fertility experts believe there’s no substitute for a woman’s uterus and that embryos should be put back into the uterine environment as quickly as possible. Since not all embryos survive until Day 5, transferring on Day 3 is a way to ensure an embryo gets to the optimal environment to thrive.  At CNY, we generally recommend transferring a day three embryo if there are fewer than four embryos on day one.

Blastocyst (Day 5) Stage Embryo Transfer

A blastocyst is an embryo that has developed into a single-layered sphere of cells encircling a fluid-filled cavity with a dense mass of cells grouped together.  Blastocysts contain anywhere from 60 to 120 cells.  This usually occurs on day five but may happen on day 6, 7, or even 8. By this stage, the embryo has differentiated into two cell types:  the trophectoderm, the cells on the periphery of the embryo that form the placenta, and the inner cell mass (ICM), the dense mass of cells on the inside that forms the fetus if the embryo implants.

A blastocyst embryo is considered to be more “special” than an earlier-stage embryo since it has a higher probability of being genetically normal, implanting, and leading to a live birth than a cleavage-stage embryo.

By delaying embryo transfer to the blastocyst stage, an embryologist is better able to select embryos with a higher probability for continued development.

An embryo that is grown to a blastocyst stage can also be genetically tested prior to transfer, which can help reduce the risk of miscarriage for some populations, avoid known genetic disorders, and select the sex of the child.

Single Embryo Transfer (SET or eSET)

A(n) (Elective) Single Embryo Transfer is the practice of transferring only one embryo into a woman’s uterus. This offers a reduced chance of multiples while maintaining a very similar rate of pregnancy. Due to the reduced risk of an eSET along with having a very similar rate of pregnancy, eSET has quickly become the gold standard practice for transferring embryos with an IVF procedure.

Multiple Embryo Transfer

A transfer of multiple embryos is quite simply the transfer of more than one embryo. While this can be done for some, there are strict guidelines that restrict the transfer of multiple embryos. Transferring a high number of embryos (or even more than one in some instances) can get a clinic shut down in today’s day and age.

Summary of Embryo Transfer Types:

Some of the above-mentioned embryo transfers are mutually exclusive, while others could be classified together:

• Fresh Embryo Transfers and Frozen Embryo Transfers are mutually exclusive
• Cleavage Transfer vs. Blastocyst Transfers are mutually exclusive
• Single Embryo Transfer vs. Multiple Embryo Transfers are mutually exclusive

That means a transfer could be a frozen single embryo blastocyst transfer, but it could not be a cleavage blastocyst transfer. That said, IVF often results in many embryos so you could do a Fresh Single Embryo Transfer followed by a Multiple Frozen Embryo Transfer months/years later from an embryo created in the same IVF cycle.

Key Decisions Regarding Embryo Transfers

When Does Embryo Transfer Occur?

The timeline for an embryo transfer is highly variable as every individual’s cycle is unique and governed by a multitude of factors being monitored closely. These factors help time a number of key events in an IVF cycle, which in turn sets the trajectory for the next step of the IVF cycle. Because the embryo transfer is the final stage of an IVF cycle, the day on which this occurs is highly variable – so it’s important not to get attached to any specific calendar or timeline during your own IVF or FET cycle.

Fresh Transfer:

Day one of a fresh transfer cycle is noted as the first day of stimulation medications (usually on day 2-4 of a woman’s natural menstrual cycle if applicable). The day of transfer is ultimately determined by the day of the egg retrieval and the developmental stage of the embryo. However, both those things are indeed variable. For instance, the ultrasound and bloodwork monitoring could determine that an extra day of stimulation is required (or less) pushing the day of the egg retrieval forward or backward. Most cleavage-stage transfers happen three days after the retrieval, and blastocyst-stage transfers typically happen five days after, but embryos, too, develop at different rates. It is indeed quite common to do a blastocyst transfer seven days after the retrieval.

Below is a sample calendar for a fresh embryo transfer.

Frozen Transfer:

Similar to a fresh transfer, each and every FET is customized to the intended parent’s cycle depending on their lining development and response to medications (if being used). While the amount of time spent on estrogen before introducing progesterone varies by person and will be determined through the help of ultrasound and blood work monitoring, the day of the embryo transfer is ultimately dependent upon the day in which progesterone is started:

• Cleavage embryos will be transferred four days after the start of progesterone.
• Blastocyst embryos will be transferred six days after the start of progesterone.

Below is a sample FET calendar.

What to Expect During Embryo Transfer

Embryo transfers take place under sterile conditions, usually in a designated transfer room at the fertility clinic. Your doctor, a nurse, the embryologist, (and your partner) will be with you. Anesthesia is usually not necessary, but a muscle relaxer or Valium is often used to help calm nerves and relax the smooth muscles of the uterus. You should take any medications that have been prescribed for you exactly as instructed. You may be asked to refrain from taking anything that is inserted vaginally (like a suppository) the morning of the transfer.

Prior to the transfer, the doctor and embryologist will confirm your name and date of birth to make sure it matches identifying information on the embryos. Then, with the assistance of the embryologist, the embryo is loaded into the transfer catheter. Around that same time, a speculum is placed into the vagina to allow visualization of the cervix, which will then be cleaned. The catheter is placed through the cervix and into the uterus using ultrasound guidance. Once in place, the embryo is gently deposited into the uterus, where it will hopefully implant.

Embryo transfer is very similar to having a pap smear. It should not hurt, but you may feel some minor discomfort when the speculum is inserted or when the catheter is passed through your cervix.

The patient is allowed to rest for about 15 minutes afterward. Follow-up instructions are given, and bloodwork is scheduled for 4-7 days post transfer and a pregnancy test for ten days post transfer.

What to do Before Embryo Transfer to Improve Chances of Success

There’s a lot that can be done before an embryo transfer to improve the odds of a successful transfer.  Most of these changes have an optimal effect if started at 30-90 days prior to the beginning of the stimulation phase of the IVF cycle as eggs start their final phase of development about 90 days before ovulation. This helps to enhance egg development and provide the best quality eggs (which make up half the growing embryos’ genetics) for your treatment cycle.

Diet & Supplementation:

• High-Fat / Low Carb Diet: Eating a high-fat / low carb diet reduces inflammation throughout the body, G.I. tract, and reproductive system. It also aids hormone function since many female hormones are made from cholesterol, which comes from fat.
• OTC Supplements: Various fertility supplements such as co-q10/ubiquinol, inositol, Vitamin D, and many others can be tremendously helpful for women and men. Fortunately, companies like Molecular Fertility have combined the dozens of recommended ingredients into a few simple products. We generally recommend females take the Peak Prenatal, VivoMega Fish Oil, Ovarian Bloom, and also consider the fertile guard to support inflammation. For males, we recommend the Male Preconception+ as well as VivoMega Fish Oil.

Prescription Medications:

Various immunological medications can help improve transfer outcomes, particularly after a history of failed implantation.  Some immunological medications include:

• Intralipids
• low dose naltrexone
• HGH
• Antibiotics
• Tacrolimus (Prograf)
• Prednisone
• Aspirin (over the counter)
• Lovenox
• hCG
• IVIG
• Filgrastim (Neupogen)
• Viagra
• Antihistamines (over the counter)
• Metformin
• Orilissa

Surgical Treatment & Immune Therapies:

• Lymphocyte Immunization Therapy (LIT): LIT is a procedure whereby white blood cells from the father to be are isolated from the father’s blood and injected into the skin of the prospective mother to introduce the husband’s immune cells to the woman’s immune system in preparation for pregnancy.  LIT therapy is often recommended after many failed IVF cycles and suspected immunologic reasons for failed implantation.
• Platelet Rich Plasma (PRP) Therapy: PRP, a concentrated platelet-rich blood product, helps to stimulate healing and tissue growth and can be used for both ovarian/egg support as well as to improve endometrial thickness and receptivity.
• Endometrial Biopsy: An endometrial biopsy  (aka scratch procedure) may be performed before the menstrual cycle of the month you wish to proceed with the transfer can be very helpful. “Scratching” the endometrium lining causes chemicals called cytokines, which promote healing, to be released. This healing process may help encourage better lining development in the following months.
• Intra-uterine hCG: Placing a small amount of Human Chorionic Gonadotropin (hCG) into the uterus prior to transfer is believed to improves the odds of implantation by up to 30%. CNY Fertility encourages the use of 500 IU of intrauterine hCG as part of our embryo transfer protocol to help jump-start the implantation process.
• Endometrial Receptivity Analysis (ERA): An ERA is a test done to evaluate a woman’s endometrial receptivity, or how likely an embryo is to stick.  The test is performed to help prevent implantation failure by identifying a woman’s unique and optimum window of implantation.
• Laparoscopy: A laparoscopy is a minimally invasive surgical procedure to visualize the inside of the abdominal and pelvic cavity to diagnose and correct Endometriosis, Uterine Fibroids, Abnormal Growths, and adhesions.
• Hysteroscopy: A hysteroscopy is a minimally invasive diagnostic and corrective procedure done to visualize the inside of the uterus to investigate and correct (if discovered) the source of abnormal uterine bleeding or suspected cause of infertility and miscarriage.  

Holistic Therapies:

• Acupuncture: Research has revealed that acupuncture can improve pregnancy rates by up to 65% in women doing in-vitro fertilization treatments .
• Massage: Massage techniques developed specifically to treat infertility, like the Maya Abdominal Massage, can be used to improve fertility by increasing blood flow to the reproductive organs, relieving blockages, decreasing inflammation. It can also help to realign the uterus and relieve stress and anxiety often associated with infertility.
• Yoga: Yoga can be used as a supplementary fertility treatment by reducing stress, improving blood flow to the reproductive organs, and balancing the immune system.

What to do After Embryo Transfer to Improve Chances of Success

Most of the prep work for successful embryo transfer happens upfront. Once transfer occurs, there’s really not too much that can be done to alter the course.  It is recommended women have a second round of acupuncture just after their transfer, as several studies show the benefit of acupuncture treatment pre and post-embryo transfer during an IVF cycle. Fourteen research studies published in Fertility and Sterility indicate that acupuncture performed before and after IVF embryo transfer has increased the rates of pregnancy by as much as 35-50% .

After Embryo Transfer Precautions

Implantation of the embryo can occur up to 72 hours after embryo transfer. Post-transfer instructions vary from clinic to clinic. While standard protocol used to be to recommend bed rest, this is no longer the case.

The experts at CNY suggests patients resume their normal routines, but are restricted from strenuous exercise, sex, or taking baths. We recommend going home, relaxing, and getting a good night’s sleep. Maintain a positive outlook, find ways to relax and connect with your partner during the dreaded “two-week wait” between transfer and pregnancy test. Try not to get too caught up in do/don’t lists. Focus on you and doing the things you like.

• Remember that women get pregnant all the time without changing their activities.
• Continue to take all medications as instructed.
• Behave as if you’re pregnant: Eat and act just like you’re pregnant.
• Stay active: You can pretty much resume your normal routine. Just avoid strenuous exercise.
• No Sex. Mother Nature must run her course.
• Avoid Extreme Temperatures: This means no hot baths, hot yoga, saunas, heating pads, or electric blankets. They can all raise the temperature of your uterus and should be avoided.

Embryo Transfer Costs:

Fresh Embryo Transfer Cost

The cost of a fresh transfer is usually included in the base cost of IVF, around $12,000 on average, and $3,900 here at CNY Fertility. Because it is included in the price of IVF, it is difficult to extrapolate out from the other services required as part of the IVF package in order to obtain the cost of just a fresh embryo transfer.

Frozen Embryo Transfer Cost

The average cost of a Frozen Embryo Transfer is around $4,000 but ranges from $1,400 (including the procedure and monitoring) here at CNY Fertility to over $6,000 at other clinics around the country.

Which Is More Expensive: Fresh or Frozen?

This may seem like a foolish question given what we just discussed, but it really depends on how you look at it.  A frozen embryo transfer could be looked at as an additional expense, particularly if it is done as the first transfer (no fresh transfer).  However, many IVF cycles result in more embryos than can be transferred at once. These embryos are frozen for future use (after a failed transfer or the successful birth). When used in this way, the cost of the frozen embryo transfer is significantly less than doing a fresh transfer, which would new IVF cycle from scratch.

IVF & Embryo Transfer Payment Calculator

To learn more about the cost of IVF and Embryo Transfers head here.

Fresh vs. Frozen Success Rates:

As you can see below, the overall success rates of frozen embryo transfers is higher when looking at large scale data from the CDC.

Despite the success rates above and notable systematic reviews of studies looking at fresh vs frozen success rates that suggest that frozen embryo transfers have higher success rates , the decision to transferring fresh or frozen embryos and which is best remains one of the largest and most heated ongoing debates in fertility medicine. While there has been a tremendous shift towards frozen embryo transfer since the development of the latest embryo freezing techniques (which allowed for FETs to have the high success rates they do today), the fact that there is still much debate shows that there’s more to the story and that each case needs to be handled on an individual basis.

Let’s start off by reviewing the two biggest factors that go into a successful embryo transfer:

• Embryo Quality: A healthy embryo without genetic defects is more likely to implant and result in a healthy baby.
• Uterine Quality & Receptivity: Uterine receptivity plays a large role in embryo implantation. If the uterus isn’t ready to receive the embryo, it’s hard for the embryo to stick. Timing and lining are critical.

Embryo Quality

Until the development of vitrification (the new freezing technique), the method of freezing embryos was very slow and could be harmful to the embryos. Survival rates from thaw were not good, and when embryos were thawed, their quality could be compromised.  This resulted in significantly poorer outcomes for frozen transfers. However, with vitrification came the ability of frozen embryos to maintain their quality. This meant that frozen embryo quality is now near-identical for both fresh and frozen embryos.

Uterine Receptivity

As mentioned earlier, the additional “biological stress” induced by the gonadotropin medications required in IVF to make the ovaries develop a large number of eggs sometimes makes it difficult for the woman to simultaneously prepare a uterus that is optimally prepared to receive an embryo.  While this is certainly not the case and fresh transfers can give just as high of odds for a successful transfer, each case must be looked at individually to ensure the uterine lining and hormones are indicative of a receptive endometrial lining.

A Patient-Centered Approach

Other studies have shown a more nuanced approach that considers the importance of certain hormone levels in determining uterine receptivity and thus when to transfer fresh embryos and when to pursue a freeze all followed by a frozen transfer cycle.

As this study indicated, there are times when fresh transfers result in success rates just as high as frozen transfers. Because costs can be a significant factor in many decisions made by patients, fresh transfers may be preferred by many. Because of this, a patient-centered approach is better than making overarching principles and guidelines. Today, most clinicians and practices consider estrogen, progesterone, and endometrial lining at the time of the IVF Trigger (as well as patient preferences) when determining if a fresh or frozen will be done.

Embryo Transfer Risks

Even though the embryo transfer process is brief, there is some inherent risk, including:

• cramping (fairly common)
• vaginal bleeding (mild bleeding fairly common)
• perforation of the uterus (extremely rare)
• infection (rare)

Also, given the success rates of each embryo transfer top off around 50%, there is a fairly high risk that the embryo fails to implant and no pregnancy occurs. There is also the risk of a multiple gestation, which carries a chance for a significant number of medical complications for both the mother and fetuses. The risk of multiples is exponentially higher when transferring more than one embryo.

The Bottom Line

An embryo transfer is the final step in an IVF procedure. It is the process of depositing an IVF Embryo safely inside the womb of the intended parent. While there are many different types of embryo transfers and the exact timeline can vary tremendously, your decisions will be guided by the help of a fertility doctor, embryologist, and other fertility specialists to optimize the outcome of your specific case.