Requirements for IVF endometrial transplantation

The uterus is where eggs are produced and fertilized eggs develop. Every organ inside the uterus is very important, especially the endometrium. Every married couple hopes to have a baby of their own, but for various reasons many couples cannot conceive naturally. After several years of trying, they can only choose in vitro fertilization. In vitro fertilization has brought hope to infertile couples. What are the requirements for in vitro fertilization and endometrial transplantation?

1. What is the endometrium?

The endometrium refers to the layer that makes up the inner wall of the uterus and is the mucous membrane that covers the uterine cavity. It is one of the most differentiated tissues in the human body. Its function is to form menstruation when not pregnant and to proliferate rapidly during pregnancy to provide nutrition for the growth and development of the embryo.

2. Cyclic changes in the endometrium

The endometrium is divided into three layers: the compact layer, the spongy layer, and the basal layer. The dense layer and spongy layer of the 2/3 inner membrane surface are collectively called the functional layer, which changes periodically due to the influence of hormones and falls off. The basal layer is the 1/3 of the endometrium close to the myometrium. It is not affected by hormones and does not undergo cyclical changes.

The thickness of the endometrium changes dynamically during different times of the month, such as ovulation and menstruation. It will continue to thicken from very thin, then fall off during menstruation, and then start to thicken from very thin again, over and over again. Below we take a 28-day menstrual cycle as an example to analyze the changes in the endometrium.

1. Endometrium during menstruation - old for new, ready to go

When the period comes (menstrual period), the endometrium is in a shedding state. It is very thin, about 1-4mm, and looks like a thin line. The boundary with the myometrium is not very clear. The endometrium at this time seems to be undergoing a renewal. After the replacement, it will bring vitality to the uterus with a brand new look. At this time, a batch of fresh basal follicles gradually awaken, preparing for the "baby-making plan".

2. Endometrium in the proliferative stage: mustering strength and striving to grow

As the menstrual period subsides, the endometrium gradually thickens under the stimulation of hormones, and can increase to about 9-14mm at one point (about 14 days during the menstrual period). At this time, the fresh follicles are undergoing a "screening" process, and eventually one follicle breaks through the siege, grows bigger and bigger and matures, while the other follicles become closed and exit the stage of history. (Expectant mothers during the ovulation induction period will experience the growth of multiple follicles).

3. The endometrium during the secretory period: Seeking stability and protecting the baby

As the follicles mature and ovulate, the endometrium enters the secretory phase (day 15-28 of the menstrual cycle) after ovulation. Under the stimulation of progesterone and estrogen, the endometrium in the secretory phase will become thicker and looser, like a soft sponge warm bed, releasing nutrients. If the egg and sperm combine, the embryo formed will look for the warmest corner on this warm bed and implant quietly. If the expectant mother does not get pregnant this month, the endometrium will be shed again after the 28th day of the menstrual cycle to usher in a new era.

3. For IVF, what is the standard for transplantation of endometrium?

The thickness of the endometrium is one of the important factors affecting embryo implantation. There is no so-called "gold standard" at present. Generally speaking, when the endometrium reaches about 0.8cm-1.4cm, it meets the "requirements" for embryo transplantation or sexual intercourse.

Theoretically, an endometrium that is too thin will inevitably reduce the chances of pregnancy, but in clinical practice, there are also some "lucky situations". For example, there was once an expectant mother whose endometrium was always hovering between 0.7-0.75cm, but after embryo transplantation, she successfully became pregnant and gave birth to a healthy baby.