The thin endometrium is only relative, if the thickness of the endometrium can reach about 9mm at the time of ovulation, the fertilized egg will be clinically implanted, so it will be pregnant. If the endometrium is less than 9mm at the time of ovulation, it is clinically difficult to get pregnant because the fertilized egg will not be able to implant, so the thickness is relative. In addition, the lining of the uterus also changes throughout the menstrual cycle, if it is just after the period, the lining is really thin, about 5-6mm. If it is in the premenstrual period, the lining of the uterus will thicken, about 1-1.2cm. So the thinness of the endometrium mainly depends on which period, if it can reach 0.5-0.6cm during ovulation, it is clinically impossible to get pregnant.