When doing IVF, we need to evaluate the ovarian function, including age and sinus follicle count and blood FSH value, and assess the endometrial tolerance, normal endometrial lining is generally above 8mm and more receptive to embryos, 10-12mm is better. In general, if the endometrium is less than 8mm, and the endometrium can reach 7mm or more, the pregnancy rate of IVF is also higher, and the pregnancy rate of IVF is generally above 50%. If the endometrium is less than 7mm, the endometrium has been damaged, so the endometrium is less tolerant and the pregnancy rate will be lower, but some people will get pregnant. Nowadays, people with endometrium over 6.5mm can also do IVF, but some people with endometrium not over 6.5mm or less than 6mm can also release embryos, there is no obvious boundary.