Understanding the basics of an embryo transfer

Often times, I see patients describing an embryo transfer as an IVF cycle, while that is a step that often comes after IVF, it should be considered as a separate part of the ART (assisted reproductive technology) process.

Whether you are just starting the process of IVF or soon preparing for an embryo transfer, understanding the process can help reduce any anxiety and empower you through knowledge. Let’s walk through, step by step, the process of preparing for an embryo transfer, what happens during the procedure, and what you can expect afterwards.

What Is an Embryo Transfer?

An embryo transfer is a critical step in the IVF process where an embryo (most commonly a day 5-7 embryo called a blastocyst) is transferred into the uterus, with the goal of achieving pregnancy. This step comes after the eggs have been retrieved from the ovaries and fertilized in a lab setting with either partner or donor sperm, creating embryos. Once an embryo has developed to a certain stage—usually within three to seven days—it is carefully placed into the uterus, where it can hopefully implant into the uterine lining and develop into a pregnancy.

Types of Embryo Transfers: Fresh vs. Frozen

There are two main types of embryo transfers: fresh and frozen.

1. Fresh Embryo Transfer: This involves transferring the embryo into the uterus 3-5 days after the egg retrieval. A day 3 embryo is known as a cleavage stage embryo and a day 5 embryo is known as a blastocyst.

2. Frozen Embryo Transfer (FET): In this case, embryos are frozen (cryopreserved) and transferred at a later time (either in the immediate next cycle or months to years later depending on whether the goal is immediate pregnancy or embryo banking/fertility preservation). Many couples opt for FET because it allows time for hormone levels to return to normal after ovarian stimulation and provides flexibility for scheduling. Many studies have also shown that pregnancy rates are higher with FET compared to fresh transfer. FET is necessary is the embryos will undergo biopsy for genetic testing (PGT) in order to help prioritize which embryo to transfer first.

The Embryo Transfer Process

1. Preparing the Uterus: Before an embryo transfer, it’s crucial that the uterine lining is well-prepared. If you’re undergoing a fresh transfer, your body may already be in an optimal state following ovarian stimulation. In this case, on the day of the egg retrieval you will be started on either a progesterone pills or suppositories or progesterone in oil (intramuscular injections) or a combination of the two. For a frozen transfer, you may be prescribed hormonal medications such as estrogen and progesterone to prepare your lining for implantation. In this case estrogen is started first to help thicken the lining and once the lining has a trilaminar pattern and is of sufficient thickness (we mostly aim for >7mm), progesterone is initiated. Five days after progesterone initiation, your transfer is performed. This implantation mimics the timeline seen during natural conception. Other protocols can be implemented, such as a natural cycle transfer or modified natural cycle (more on that another time!).

2. The Procedure: The embryo transfer is a relatively simple and quick procedure that usually does not require anesthesia. A thin, flexible catheter containing the embryo is gently placed into the uterus through the cervix. An ultrasound is used to guide the catheter and ensure precise placement of the embryo.
3. After the Transfer: Once the embryo is transferred, you will advised to immediately get up to go empty your bladder (bedrest after transfer decreases pregnancy rates!).

What Happens Next?

After the transfer, the waiting period begins. Typically, it takes about 9–14 days before a blood test (beta-hCG) can confirm whether the embryo has successfully implanted. This waiting period can be an emotionally intense time, so it’s essential to take care of your mental and emotional health during these days. Things like massage therapy and acupuncture can help keep the mind calm during this time. Other tools such as mindfulness techniques, or even a short vacation afterwards can help you manage your stress during the waiting period. Support from loved ones and your fertility team can also really make a significant

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