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When undergoing a frozen embryo transfer (FET), preparing your uterine lining is crucial for a successful implantation. The goal is to mimic an optimal menstrual cycle using hormonal medications to thicken and mature the endometrium. In this post, we’ll guide you through the steps involved in preparing for an FET and discuss potential side effects and complications.

Pre-treatment: Suppressing Ovulation

Before your FET cycle begins, your doctor may suppress your hormones to prevent unexpected ovulation and better control the timing of your cycle. This can be achieved by:

1. Oral Contraceptive Pills: These are used to regulate the menstrual cycle and create a controlled environment for the FET. Possible side effects include spotting, headaches, breast tenderness, nausea, and swelling. In rare cases, oral contraceptives can increase the risk of blood clots or stroke.
2. GnRH Agonists: These medications initially stimulate the pituitary gland to release FSH and LH, but after a few days of continuous use, they suppress the natural ovarian function. Due to the low estrogen levels during this phase, you may experience menopausal-like side effects such as headaches, hot flashes, muscle aches, and mood fluctuations. However, there are no known long-term or serious side effects from GnRH agonists.

Assessing Baseline Hormone Levels and Uterine Lining

‍Just before your FET cycle begins, an ultrasound and blood hormone test may be performed to assess your baseline hormone levels and the thickness of your uterine lining. This information will help your doctor determine the next steps for hormone supplementation.

‍Estrogen for Endometrial Growth

‍The first phase of an FET cycle involves the use of estrogen to promote the growth of the endometrium. Estrogen can be administered orally, via skin patch, vaginally, or by injection. While generally well-tolerated, estrogen may cause local reactions, and in extremely rare cases, it can increase the risk of blood clots or stroke.

An ultrasound and blood work will be performed to assess the response of your endometrium to estrogen. The goal is for the lining to reach an ideal thickness greater than 7mm for embryo implantation. (Related: How Female Hormone Imbalances Are Evaluated and Treated Before IVF)

‍Adding Progesterone to the Protocol

‍If estrogen treatment is successful and your endometrial lining has thickened appropriately, progesterone will be added to the protocol. Progesterone prepares the endometrium for implantation by stabilizing the uterine lining.

Progesterone can be administered in several forms:

• Vaginal capsules, tablets, or suppositories
• Intramuscular injections

In approximately 1% of cases, patients may experience an allergic reaction to intramuscular progesterone, which can manifest as a skin rash or irritation at the injection site. If the reaction is severe (redness, pain, swelling), your doctor may switch you to a different form of progesterone.

‍Potential Complications and Next Steps

‍Unexpected ovulation can happen during a frozen medicated cycle (FET), but it occurs in less than 3% of cases. If ovulation occurs prematurely, your FET cycle will be canceled. Your medical team will provide guidance on the next steps, which may involve a new protocol for the next cycle, such as subcutaneous injections of Lupron to prevent ovulation. (Related: What to Do After an Unsuccessful IVF Cycle)

‍If all goes according to plan, your doctor will schedule the day and time of your embryo transfer. The timing of the transfer is critical, as the embryo must be placed into the uterus at the optimal moment when the lining is most receptive.

‍Preparing your uterine lining for an FET is a critical step in your fertility journey. By understanding the medications, side effects, and potential complications involved, you can work closely with your medical team to optimize your chances of a successful embryo transfer and pregnancy.

The content on this blog is for informational purposes only and is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always consult with a qualified healthcare provider before making any health-related decisions or implementing any medical information shared here.