In the assisted human reproductive technology cycle, the implantation and implantation of embryos is like when we plant crops and sow seeds, we need firstly good quality seeds (embryos) and secondly good soil (i.e. endometrium). The thickness of the endometrium and its receptivity are the key conditions for embryo implantation and pregnancy. During the “implantation window”, the endometrial epithelium and stromal cells undergo a series of differentiations to adapt to the needs of embryo implantation. The endometrial thickness during this period reflects the degree of endometrial proliferation. The quality “seed” and the rich “soil” complete a precise “dialogue” to allow for successful rooting and germination. However, in clinical practice, the problem of thin endometrium in the ART cycle is still a clinical treatment problem, and in the face of barren land, the crop growers can only make extra efforts to fertilize. And the harvest of the crop remains a challenging issue. I. How thick do I need the soil at least? Endometrial tolerance is now generally assessed clinically in terms of endometrial molecular biology, morphology and ultrasound factors (e.g., endometrial thickness, echogenicity, volume and blood flow characteristics). Among the many parameters used to evaluate endometrial tolerance, ultrasound measurement of endometrial thickness is an easy and reliable method. The endometrial thickness on the day of HCG or embryo transfer is now often used clinically as a target for endometrial assessment. Endometrial thickness in in vitro fertilization (IVF) cycles is positively correlated with pregnancy rate, the more fertile the soil the higher the growing capacity and the better the harvest. There is no uniformity in the definition of the minimum endometrial thickness that will result in a successful pregnancy, and it is clinically accepted that implantation rates are significantly higher when the endometrium is >7 mm on implantation day. At the same time, studies have concluded that transferring high-quality blastocysts with an endometrial thickness of only 6 mm can still result in a pregnancy rate of more than 30%, so it is not advisable to abandon the transfer simply because of a thin endometrium. Successful twin pregnancies with an endometrium of only 4 mm have been reported. Good quality seeds can take root and thrive on poor soil with their hardy growth ability. The Huangshan welcoming pine is a solemn sight in the crevice of the rocky cliff. Second, why is my crop a barren field? Even so, we still want our piece of land to be fertile in relation to our harvest rate. But, why is my crop a barren field? The causes of a thin endometrium are complex and the following are some of the common causes: 1. Age: In addition to affecting egg quality, some studies have confirmed that age factors also affect the endometrium. It was found that endometrial thickness was negatively correlated with the age factor. Experiments in mice found that estrogen receptors in the uterus decreased with age, while endometrial stromal vessels and endometrial vascular sclerosis increased and endometrial glandular and stromal apoptosis increased, leading to a decrease in endometrial blood supply. In addition, age affects the quality and growth of the eggs. The combined effect of these factors leads to thinning of the endometrium with age. 2. History of uterine surgery and genital tuberculosis: Repeated intrauterine operations damage the endometrium, which in severe cases leads to impaired endometrial repair, often resulting in endometrial thinning or uterine adhesions. Hysteroscopy performed 3-12 months after abortion revealed a 37.6% incidence of uterine adhesions. The hysteroscopy showed varying degrees of narrowing and shallowing of the uterine cavity, extensive scarring and myxomatous adhesion cord formation in the uterine cavity, thin or no endometrium, and most of the uterine cavity was closed with adhesions, as if it were a “concrete floor”. In addition, endometrial tuberculosis damages the endometrium, resulting in endometrial fibrous scar formation and impaired repair, which affects pregnancy and is also a common clinical cause of endometrial thinning. In addition, studies have concluded that some unexplained endometrial phenotypic thinness may be related to genetic polymorphisms and associated factors such as subendometrial blood flow. Third, what should I do when I grow crops on barren land? The land is barren but not exchangeable, and I have to plant crops on it. What do I need to do with my doctor to work together to plant the seeds up? 1, etiological treatment: for endometrial adhesions, endometrial tuberculosis and other causes of endometrial fiber scarring resulting in thin endometrium, the first to remove the cause of treatment. With the development of hysteroscopic technology, hysteroscopic hysterectomy with targeted separation or incision of uterine adhesions under direct vision has become the standard method for treating uterine adhesions, restoring the normal shape of the uterine cavity and increasing the thickness of the endometrium, which is conducive to further measures to help pregnancy. Therefore, if necessary, doctors will arrange hysteroscopy, as if before we plant crops, we first need to go to the crop field to carefully survey some, remove those stones, debris, to ensure that there can be a sufficient space to cultivate the seeds. 2, diligent fertilization: endometrial thinness is the current situation that we can hardly change, to change the thinking, we try to increase the thickness of the endometrium at the same time, to improve the ability of the endometrium to accept embryos (endometrial tolerance) is also helpful. The “fertilizer” is the medication that is commonly used in clinical practice for endometrial growth. Like the “fertilizers” in the farmer’s market, there are various brands and effects, and the agronomist (doctor) will give guidance on which one to use and how much to use, depending on the characteristics of each plot of land. In conjunction with medicine, herbal and dietary regimen is also beneficial, but only as an aid to treatment. People who have ridden the train often see grasses and trees still growing and thriving in the stone-built slopes along the roadside, and one cannot help but marvel at the tenacity of life. It is indeed difficult to grow crops in poor soil, but we need to build confidence and keep trying. The seed that eventually grows down must have a strong vitality that is worthy of our attention. Let’s work together for that extraordinary little life.