Menstruation delayed for four days uterine lining 5mm usually will not be pregnant. The endometrial lining of the uterus is 5mm, generally not pregnant, because the endometrial lining of the uterus is thin, is not suitable for the fertilization of the egg, this situation basically will not be pregnant, if you want to rule out the possibility of early pregnancy, it is best to go to the hospital for further blood tests HCG and hormone six. Early or delayed menstruation within 7 days is generally a normal phenomenon, do not have to be too nervous, you can first observe, maintain good habits, avoid staying up late, eat more fresh vegetables and fruits. If there is a delay in menstruation or other uncomfortable symptoms, you should consult a doctor as soon as possible, after ruling out early pregnancy and a clear diagnosis, under the guidance of the doctor to carry out standardized treatment, so as to avoid delaying the condition.