Achieving the Ideal Uterine Lining for a Successful Embryo Transfer

Achieving the Ideal Uterine Lining for a Successful Embryo Transfer

Gynaecologist, expert in Assisted Reproduction, risk pregnancy and laparoscopy at UR Vistahermosa, Spain.

Embarking on the journey of assisted reproductive technologies like in vitro fertilisation (IVF) can be a profound and life-changing decision. For those pursuing IVF, understanding and preparing the uterine lining are crucial components of the process. In this comprehensive guide made by specialists of UR Vistahermosa, we will delve into the significance of the uterine lining, explore various strategies for its preparation, discuss diagnostic tests and procedures, and answer common questions that may arise during this transformative journey.

Understanding the Uterine Lining

The uterine lining, also referred to as the endometrial lining, is the innermost layer of the uterus. Its significance lies in its dynamic nature, as it undergoes cyclical changes throughout the menstrual cycle. These changes are orchestrated by hormonal fluctuations and are essential for embryo implantation and the success of pregnancy.

The uterine lining consists of two primary layers:

Basal Layer
This layer remains relatively stable throughout the menstrual cycle and serves as the foundation for the endometrial lining.

Functional Layer
The functional layer is the part of the uterine lining that undergoes cyclical changes in response to hormonal signals. It thickens and becomes more vascularized during the menstrual cycle, creating an optimal environment for embryo implantation.

Uterine Lining for IVF – Strategies, Process, and Preparation

Preparing the uterine lining for embryo transfer is a meticulous and well-coordinated process. It involves several strategies and steps to ensure that the uterine environment is conducive to successful implantation.

Hormonal Medications
Hormonal medications are a cornerstone of uterine lining preparation. Two primary hormones used in IVF are estrogen and progesterone:

  • Estrogen: Early in the IVF cycle, estrogen is administered to stimulate the growth and thickening of the uterine lining. It helps create the lush, receptive environment needed for embryo implantation.
  • Progesterone: As the IVF cycle progresses, progesterone is introduced. It serves to prepare the uterine lining for embryo implantation and maintains the uterine environment conducive to pregnancy.

Timing is of the essence in IVF. The preparation of the uterine lining must align precisely with the development of the embryos. This synchronization ensures that when the uterine lining is optimally receptive, the embryos are at the appropriate stage for transfer.

“As the embryos are developing the first few days in the laboratory, we have to administer the same days of progesterone as the days of embryo life.”

Dr. Susanna Malkhasian

Regular monitoring is a fundamental aspect of uterine lining preparation. Transvaginal ultrasounds are commonly employed to measure the thickness and quality of the uterine lining. These ultrasounds provide crucial insights into the progress of lining development.

Thus, although there are standard times for the development of endometrial thickness, in each woman it may be different and sometimes more days of preparation or even higher doses of oestrogens are needed to reach the adequate thickness.

In addition, spontaneous ovulation can sometimes occur despite the ovaries being held back by the medication, which is why we also have to monitor it ultrasonographically.

Other types of medication

For some years now, we have known that this uterine cavity is not sterile, but that the inner layer is populated by many micro-organisms (mainly bacteria and fungi), collectively known as the endometrial microbiota. Studies have shown the positive effect of the presence of an abundant population of the Lactobacillus group on embryo implantation, which is why we recommend oral probiotic supplementation during endometrial preparation.

Lifestyle and Diet
While hormonal medications play a significant role in preparing the uterine lining, lifestyle factors also influence the success of IVF.
Here are some considerations:

A balanced diet rich in essential nutrients, including vitamins and minerals, supports overall reproductive health. Incorporate fruits, vegetables, whole grains, lean proteins, and healthy fats into your meals.
Staying adequately hydrated is essential for general health and can contribute to a favourable uterine lining.
Rest and Stress Management
Ensure you get sufficient rest and engage in stress-reduction techniques such as yoga, meditation, or mindfulness. High-stress levels can negatively impact fertility.

Regular, moderate exercise can promote overall well-being. However, excessive exercise or strenuous workouts may affect fertility negatively. Strike a balance that works for you.
Avoid Environmental Toxins: Minimize exposure to environmental toxins and chemicals that may interfere with fertility. This includes avoiding smoking, alcohol, and recreational drugs.
Maintain a Healthy Weight
Achieving and maintaining a healthy body weight is crucial. Both underweight and overweight conditions can affect fertility and uterine lining quality.

“Use essential vitamin supplements for pregnancy, as well as probiotics designed for the female genital tract.”

Dr. Susanna Malkhasian

Uterine Lining for IVF – Tests and Other Procedures

Before proceeding with embryo transfer, several diagnostic tests and procedures are conducted to assess the readiness of the uterine lining. These tests are essential in guiding the timing of the transfer and determining whether any additional interventions are necessary.

Ultrasound Examinations:
Transvaginal ultrasounds are the primary tool used to monitor the uterine lining. This non-invasive procedure allows for the accurate measurement of endometrial thickness.

Endometrial Thickness:
The optimal endometrial thickness can vary among individuals. However, a range of 7 to 15 millimetres is often considered favourable for embryo transfer. It’s crucial to note that other factors, such as the quality of the lining and its receptivity, also influence success.

“In addition, there are women who neither in their natural cycles, nor by administering high doses of hormones, reach this thickness. In these cases, we use additional medication to improve endometrial vascularisation. We also resort to newer techniques such as the administration of platelet-rich plasma during endometrial preparation, which is giving very good results in these cases of refractory endometrium.”

Dr. Susanna Malkhasian

Blood Tests
Hormone levels play a pivotal role in uterine lining preparation. Blood tests, particularly for estradiol (a form of estrogen) and progesterone, are conducted to assess hormonal balance.

Estradiol Levels
Monitoring estradiol levels helps ensure that the uterine lining is responding appropriately to estrogen supplementation. Although this is an optional test, if the endometrium shows adequate thickness and appearance on ultrasound, we know that the medication is having its effect.

Progesterone Levels
The introduction of progesterone is carefully timed to create a receptive uterine environment. Blood tests help verify that progesterone levels are at the desired range.

If with the standard doses normally administered vaginally, it is found that the progesterone levels in the blood are not sufficient, we look for another route of administration to increase its absorption.

Hysteroscopy: In some cases, a hysteroscopy may be recommended. This minimally invasive procedure involves the insertion of a thin, flexible tube with a camera (hysteroscope) through the cervix and into the uterus. It allows for direct visualization of the uterine cavity.
Purpose: Hysteroscopy can help identify and address structural abnormalities within the uterus, such as polyps or fibroids, which could hinder embryo implantation.

Endometrial Biopsy
An endometrial biopsy may be performed to assess the quality of the uterine lining, as well as to diagnose the presence of chronic asymptomatic infections. During this procedure, a small tissue sample is obtained from the endometrium and analysed for specific markers associated with receptivity.
Timing: The results of an endometrial biopsy can guide the timing of embryo transfer. If the lining is deemed receptive, the transfer may be scheduled accordingly.

Mock Embryo Transfer
In preparation for the actual embryo transfer, a mock transfer may be performed. This practice run allows the medical team to assess the ease and accuracy of the transfer procedure and ensure that everything is for the actual transfer.

Do’s and Don’ts for Uterine Lining Preparation

To optimise the receptivity of the uterine lining, it’s essential to follow certain guidelines before, during, and after preparation:

Uterine Lining Do’s

  • Follow Medication Instructions: Adhere strictly to the prescribed medication regimen provided by your fertility specialist. This includes precise timing, dosage, and administration methods for hormonal medications.
  • Maintain a Healthy Diet: Consume a balanced diet rich in essential nutrients. Incorporate a variety of fruits, vegetables, whole grains, lean proteins, and healthy fats into your meals.
  • Stay Hydrated: Proper hydration is essential for overall health and can contribute to a healthier uterine lining.
  • Get Adequate Rest: Prioritize sleep and ensure you get enough rest. A well-rested body is better equipped to respond positively to fertility treatments.
  • Manage Stress: Engage in stress-reduction techniques like yoga, meditation, deep breathing exercises, or mindfulness. High-stress levels can negatively impact fertility. Sometimes, outside professional help is available, such as fertility psychologists, who can be of great help in this process.

Uterine Lining Don’ts

  • Avoid Smoking: Smoking has known detrimental effects on fertility and the uterine lining. Quitting smoking before and during IVF treatment is highly recommended.
  • Limit Alcohol Intake: Excessive alcohol consumption can harm both fertility and the uterine lining. Minimize alcohol intake or abstain entirely during IVF preparation.
  • Reduce Caffeine: While moderate caffeine consumption is generally considered safe, excessive intake should be avoided, as it may impact fertility.
  • Steer Clear of Hot Baths: Hot baths, saunas, and hot tubs should be avoided during the preparation phase. Elevated body temperature can potentially affect implantation.
  • Minimize Stress: High-stress levels can negatively affect fertility. Implement relaxation techniques and prioritize self-care to manage stress effectively. I think this repeats itself and better just stay at the top of the Do’s.

Additional Costs and Financial Considerations

While undergoing IVF and uterine lining preparation, you may wonder about potential additional costs. These costs can vary depending on several factors:

Medication Costs
The cost of hormonal medications can vary based on the type, dosage, and duration of treatment. Some patients may require multiple cycles of medication.

Monitoring Expenses
Regular ultrasounds and blood tests are essential for monitoring the progress of the uterine lining. These tests may incur additional costs.

Diagnostic Procedures
If additional tests or procedures, such as hysteroscopy or endometrial biopsy, are recommended, they may involve additional expenses.

Fertility Clinic Fees
Fertility clinics typically charge fees for various services, including consultations, embryo transfer, and laboratory work. These fees can vary widely between clinics.

Insurance Coverage
It’s essential to check with your health insurance provider to determine if any aspects of IVF treatment, including uterine lining preparation, are covered by your policy. Some insurance plans may offer partial or full coverage.

Financial Assistance
Some fertility clinics and organizations offer financial assistance programs or grants to help offset the costs of IVF treatment, including uterine lining preparation.

It’s crucial to have open and transparent communication with your fertility clinic about the potential costs involved. They can provide you with a detailed breakdown of expenses and discuss any available financial assistance options.

Uterine lining – Frequently Asked Questions

Let’s address common questions that patients often have concerning uterine lining preparation:

What is the best lining before embryo transfer?

While the ideal uterine lining thickness can vary, it’s often considered optimal within the range of 7 to 15 millimetres. However, it’s crucial to understand that thickness alone isn’t the only factor determining success. The quality and receptivity of the lining also play a significant role.

“In addition, some women, because of their physiological characteristics, never reach these thicknesses and we do get pregnancies with smaller endometrial lines.” Dr. Susanna Malkhasian

How do I prepare my uterus for embryo transfer?

Preparing the uterus involves a comprehensive approach, including hormonal medications, monitoring, and lifestyle adjustments tailored to your specific needs. Your fertility specialist will create a customized plan for you.

When should I do an endometrial scratch before FET?

Endometrial scratching is typically performed in the menstrual cycle preceding embryo transfer. The exact timing may vary, so consult your doctor for precise recommendations.

Is a 12mm lining good for embryo transfer?

While a lining thickness of 12 millimetres can be considered favourable, other factors, such as the quality and receptivity of the lining, also influence success.

How can I thicken my uterine lining fast?

If your uterine lining is not thickening as desired, your doctor may adjust your medication protocol or recommend supplements like estrogen in higher doses or other medication to increase endometrial vascularity, to promote lining growth. It’s essential to follow their guidance for the best results.

How do I keep my uterus warm for implantation?

The concept of keeping the uterus warm for implantation is based on the idea of maintaining a warm core body temperature through relaxation techniques. While some people believe this may aid implantation, scientific evidence supporting this concept is limited.

How can I increase my chances of embryo transfer success?

To maximize your chances of success, it’s crucial to follow your doctor’s instructions diligently, maintain a healthy lifestyle, and stay informed about your treatment plan. Good overall health and adherence to recommended protocols can enhance your chances of a successful embryo transfer and, ultimately, a healthy pregnancy.

Real Patient Study Case of UR Vistahermosa

Patient, a 41 year old woman, with no medical or surgical history of interest, except for low ovarian reserve (antimullerian hormone of 0.38), who after an unsuccessful IVF cycle attempt with her partner (no embryo was obtained for transfer), decided to undergo Ovodonation treatment.

After donor selection, the endometrial preparation protocol is proposed for the patient and standard ovarian stimulation for the donor.

The treatment for both women begins with the administration of contraceptive pills, in order to synchronise their menstrual cycles and to be able to perform the first embryo transfer “fresh” (without the need to freeze the embryo).

In this case, the patient had taken the contraceptive pill from the first day of her period until 16 days in total. On the same day, a Decapeptyl injection was administered to ensure that her ovaries were at rest during the endometrial preparation and that no unforeseen events (such as the embryo freezing) would occur.

On discontinuing the contraceptive pills, on the third day she began to have period-like spotting and this is when we began the endometrial preparation itself. We used the hormonal protocol with oestrogens in increasing doses, starting with a dose of 2mg of oestradiol valerate per day and gradually increasing to the recommended dose of 6mg per day (one oral pill every 8 hours).
At her first ultrasound check-up, on day 13 of the cycle, the endometrium looked good in triple line and was 6 mm thick, so it was decided to wait a few days and increase the dose of oestrogen by one more pill a day (8mg in total).

At the next check-up, after 3 days, she had an endometrium of 8.5mm, which meant that she was ready to schedule the embryo transfer.

In this case, we had to adapt to the date of the donor’s oocyte puncture and the days of embryo development in the laboratory.

So, according to the calculations, the patient had to start the administration of progesterone (in vaginal oocytes) from the following night (so, by the day of the transfer, she would have been on progesterone for 5 days). In addition, we always recommend the use of prophylactic antibiotics in these 5 days prior to the transfer.

On the day of the transfer we had 5 embryos in blastocyst stage of A,A,B,B,B,B qualities.
A quality A embryo was transferred, with easy access to the uterine cavity and good ultrasound visualisation.

The remaining four embryos were vitrified while awaiting the results of this transfer, which we hope, together with the entire UR Vistahermosa team, will end with a positive pregnancy test!

Final Thoughts

In conclusion, achieving the ideal uterine lining for a successful embryo transfer is a vital step in the IVF journey.

It should be borne in mind that despite having good quality embryos and the endometrium in perfect condition, fulfilling the previously developed characteristics, pregnancies are not always achieved. In these cases it may simply be for statistical reasons or for reasons that are not always known.
While there are no guarantees in fertility treatment, at UR Vistahermosa we always remind our patients that working closely with your medical team and following their recommendations can significantly improve your chances of a positive outcome.

Every individual’s situation is unique, and patience, optimism, and a supportive network are essential throughout the process. Remember that building a family through IVF is a journey filled with hope and determination, and you are not alone on this path.

As you embark on this transformative journey, may you find the strength and resilience needed to navigate its challenges and the joy and fulfilment that come with achieving your dream of parenthood. We wish you the very best on your path to building your family through IVF.

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Dr. Susanna Malkhasian
Dr. Susanna Malkhasian
Dr. Susanna Malkhasian is a renowned specialist in Gynaecology and Obstetrics. She currently works as a gynaecologist at UR Vistahermosa and is an expert in Assisted Reproduction, risk pregnancy and laparoscopy. She studied Medicine and Surgery at the Miguel Hernández University of Elche and later specialised via MIR at the Marina Baixa Hospital. She also completed a Master's Degree in Human Reproduction at the Universidad Rey Juan Carlos.
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