The success of a healthy pregnancy achieved through a Frozen Embryo Transfer (FET) process has increased substantially in recent years. 

Perks of waiting for an FET vs doing a fresh transfer include allowing your body to heal after the egg retrieval, doing genetic testing (PGS/PGT) on the embryos and fully controlling the development of the uterine environment (unless you opt for a natural transfer cycle).

Some of the cons of going with an FET are longer wait times and the additional costs of medications and monitoring.

The decision to go with an FET should be made jointly by your RE, the embryologist and yourself. Once you’ve agreed on a FET the next question is if you’ll have a natural or controlled protocol?

Natural Frozen Embryo Transfer Cycle:

A natural FET cycle allows your transfer to follow your body’s lead. You will wait for your menstrual cycle to begin, and have a baseline monitoring appointment 7-10 days later. 

The monitoring appointment will include an ultrasound to check the progress of your uterine lining and follicles, as well as to make sure there aren’t any cysts in the way. Labs will be drawn to check adequate estrogen and progesterone levels.

Once your lining and follicles are determined to be ‘matured’, you will be instructed to trigger ovulation and begin the medicated portion of your transfer protocol. 

Controlled Frozen Embryo Transfer Cycle:

A controlled FET often begins with a baseline monitoring appointment around the time you ovulate (between day 13-15 of your cycle). 

If no cysts are present, the medicated part of the protocol starts by suppressing the woman’s pituitary gland to reduce the chances of unexpected ovulation. This is done with approximately two weeks of Gonadotropin-releasing hormone agonist (GnRH agonist) injections.

A second monitoring appointment is scheduled to assess the full suppression of your ovaries, and if satisfactory you’ll begin to prime your uterine lining using estrogen hormonal supplements. Estrogen acts to thicken and mature the uterine lining – like the natural estrogen produced by a developing egg follicle during a normal menstrual cycle.

You will continue to be monitored until your uterine lining reaches at least 8mm, at which point you are ready to transfer prep.

Preparing for your Embryo Transfer:

Once you ovulate via trigger and/or are cleared for transfer during a controlled cycle, you’ll add progesterone to your protocol. Progesterone is a medication administered to make the uterine lining receptive to the implantation of the embryo. 

Typically, progesterone is administered in a combination of oral, suppository and/or injections. The regimen of progesterone administration completes the final stage of the Frozen Embryo Transfer (FET) preparation process and sets the actual embryo transfer procedure in motion for 5 days later (when transferring a blastocyst). 

The Day of Your Embryo Transfer:

You’ll be asked to arrive at your clinic with a full bladder (drinking up to 1 liter of water). You’ll get checked in, change into your medical gown, and asked to identify yourself and the now thawed Embryo. 

Your Embryo(s) are placed in a catheter, and inserted through your cervix into your uterus under ultrasound guidance. The procedure itself is usually painless and doesn’t take more than a few minutes. 

Post Embryo Transfer:

You’ll continue to take your medication protocol and be given an official pregnancy test date. Most clinics will require a BETA Hcg blood test and others (mostly in the UK) will ask you to confirm the cycle’s outcome via a home pregnancy test. 

In the Embie app you’re able to create your transfer protocols by scheduling your transfer, tracking your medication protocol, and entering your appointments and  the results of your cycle all in one convenient place.