My Journey with Cushing’s disease
At 30 years old, I was fit, healthy and naturally a size 8–10. I knew my body well, which is why, when it started to
When I first thought about the topic of embryo transfer, the vision in my head was of Phoebe Buffay from the sitcom Friends sitting backwards in an armchair with her legs up the back, hoping to help the embryos transferred to her uterus implant. She sings a cute little song before running to the bathroom to take a pregnancy test.
The comic relief, and edited for TV content, can’t do justice to the actual procedure, the emotions it evokes, and the hope it can bring to those who experience it. Let’s take a look to find out what an embryo transfer entails, and how it has helped so many people become pregnant since 1978.
Before an embryo is transferred, it must be created. Then comes a series of stages in development, followed by transfer to a uterus. First, let’s find what an embryo is and how one is created.
An embryo is the product of an egg that has been fertilized by sperm and is in the process of developing into a fetus. This is the time when the cells rapidly divide and multiply and, if this happens in a uterus, implantation occurs.
This early stage of development lasts up to 10 weeks of pregnancy when the embryo becomes a fetus. In medical terms, a fetus is not considered a baby until after it is born, but many refer to their fetus as a baby before this.
Most people see their baby after it has become a fetus as the first ultrasounds usually occur around eight weeks. Before this, the embryo is a cluster of cells (called blastocyst) and isn’t visible through ultrasound yet.
Eggs are collected and united with sperm outside of the body to create an embryo to transfer. This can be done with eggs provided by the person whose uterus will be carrying the fetus, or donor eggs. Sperm is provided through sperm donation, or the prospective parent.
Embryos can be frozen or fresh before transfer. Each method has different timelines and success rates.
An embryo must go through some stages of development before it is ready for transfer. Let’s look at those now.
Two treatments that use embryo transfer to achieve pregnancy are in vitro fertilization (IVF), and the lesser known, intracytoplasmic sperm injection (ICSI). Each uses embryos that have gone through a series of stages marked by development, and chosen at specific ages to transfer.
At day three, the embryo’s cells are dividing and multiplying quickly. If transferred at this stage, it is usually necessary to transfer a larger number of embryos for the best chance at success. However, this also increases the chance of multiples.
By day five or six an embryo has finished its rapid cell division and growth and is now a blastocyst. This stage usually has the best chance at implantation, and fewer embryos can be transferred at once.
By day six, the chance of the embryo becoming a strong, healthy, baby is at a peak.
Embryos are also chosen according to their viability. An euploid embryo is an embryo that has the correct number of chromosomes. This kind of embryo has the best chances of survival and successful implantation, hopefully leading to a healthy pregnancy carried to term.
The process of selecting embryos for transfer is called grading. The embryos might undergo genetic testing, be measured, and be tested for how they are developing in terms of how many and how healthy the development is and how likely they are to survive to live birth.
For older women, or those who have had multiple failed rounds of IVF who wish to conceive, there is a procedure called assisted hatching. In this procedure, a small hole is put into the zona pellucida, the membrane surrounding the embryo, to make it easier to break out and implant. It is important to note that this can only be done on fresh embryos, not ones that have been previously frozen.
In a study called: Role of Embryo Glue as a transfer medium in the outcome of fresh non-donor in-vitro fertilization cycles, we learn:
“EmbryoGlue is a hyaluronan-enriched embryo transfer (ET) medium which aids in implantation of embryos, hence, improves pregnancy rates in in-vitro fertilization-ET cycles (IVF-ET).”
The embryos are placed into the glue for a short time before the transfer. This is used in place of other mediums that are more commonly used.
The same study concluded: “It is difficult to conclude a favorable role of EmbryoGlue in IVF-ET cycles with a good prognosis. However, in patients with recurrent implantation failure, it may be considered as a useful transfer medium.”
When embryo transfer day comes, the patient might be given a mild sedative and, though the procedure is normally painless, there could be some cramping. Then a small thin tube called a catheter will be inserted into the uterus through the vagina and cervix. The doctor will inject one or more embryos with some fluid with a syringe through the catheter to the uterus.
Frozen embryo transfer, or FET fertility treatment, is done using previously frozen embryos. Some people choose to freeze embryos for later use. This can be done through a donor, or prospective parent.
A frozen blastocyst transfer is most commonly used. This is an embryo that has been frozen as a day five embryo (or six) and is thawed then readied for transfer.
Fresh embryos can be a way to achieve pregnancy sooner. This is because the embryo can be transferred five or six days after creation.
Overall embryo transfer success rates are 50% of IVF procedures in women ages 35 and under resulting in a live birth. For women ages 42 and older, 3.9% of the egg transfers resulted in a birth, according to the CDC.
The rates were a bit higher for people using donor eggs. This may be due to egg quality.
In a study called, Pregnancy outcomes following in vitro fertilization using fresh or frozen embryo transfer we learn: “Fertility was achieved in 313 (19.23%) and 356 (28.62%) patients, who underwent fresh ET and FET, respectively. The rates of clinical pregnancy, ongoing pregnancy, and live births were significantly higher in the FET group than the fresh ET group.
“The incidence of multiple pregnancies, perinatal mortality, abortion in the first trimester, preterm delivery, and low birth weight were significantly higher among fresh ET group [38 (35.51%), 15 (14.50%), 72 (23.01%), 26 (8.30%), and 33 (10.54%), respectively] than in the FET group [25 (15.33%), 6 (6.87%), 63 (17.69%), 14 (3.93%), and 20 (5.61%); p<0.05].
“In addition, the incidence of ectopic pregnancies, abortion in the second trimester, gestational diabetes, preeclampsia, and placenta previa were higher in the fresh ET group, but not significantly so (p>0.05).”
This leads us to the conclusion that success rates transfer with frozen embryos may be higher than with fresh embryos. However, every situation is different, and the decision to use fresh or frozen embryos must be made based on the circumstances and recommendations of medical professionals.
The period of time after the transfer before pregnancy can be confirmed is around two weeks. This is commonly referred to as the Two Week Wait. Let’s look at how things go after embryo transfer day by day.
The embryo hatches out of its shell and begins to attach itself to the uterus. The cells that will be the fetus and placenta develop as the blastocyst goes deeper and deeper into the lining of the uterus.
The blastocyst implantation usually occurs 6 to 10 days after transfer. This is when the pregnancy hormone, hCG, begins to be produced. As time goes by, more and more hCG is secreted into the bloodstream, and it can be detected around days 9-14.
When the two week wait is over, and pregnancy is hopefully confirmed, the rest of the journey begins. The excitement and joy of watching the fetus grow and develop can commence, and the hope of birth rises.
The process of embryo transfer is much simpler than the steps that must be taken to get there. However, when it is done, pregnancy can happen. Though infertility is not easy to go through, transferring embryos has helped many achieve their dream of becoming parents.
Only you and your doctor can decide if these procedures are right for you. The possibility of using donors, or surrogate mothers, is out there as well and can make the difference for lots of parents.
If you are wanting to conceive via embryo transfer through fertility treatments, there is hope! I wish you all the best on your journey to parenthood, and I hope that this article has been helpful to you.
Singh, N., Gupta, M., Kriplani, A., & Vanamail, P. (2015). Role of Embryo Glue as a transfer medium in the outcome of fresh non-donor in-vitro fertilization cycles. Journal of human reproductive sciences, 8(4), 214–217. ncbi.nlm.nih.gov/pmc/articles/PMC4691973/
Zargar, M., Dehdashti, S., Najafian, M., & Choghakabodi, P. M. (2021). Pregnancy outcomes following in vitro fertilization using fresh or frozen embryo transfer. JBRA assisted reproduction, 25(4), 570–574. doi.org/10.5935/1518-0557.20210024
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