It takes 6-7 days for a pregnancy to be fertilized and the fertilized egg is then transplanted into the uterine cavity to settle, grow and develop. An increased chorionic gonadotropin level on a blood test is usually highly suspicious for early pregnancy. Under normal circumstances, a woman who has normal sexual intercourse during ovulation will have her blood drawn again one week after her menstrual period has been postponed to test for persistently elevated chorionic gonadotropin levels. And do gynecological ultrasound examination, the uterine cavity has a full growth of pregnancy sacs and the appearance of fetal buds, in order to prove that the woman occurred intrauterine pregnancy. In a few cases, if the woman’s menstrual cycle is delayed, or there is a fertilized egg development is slow, the time of implantation is late, but also when the woman in the delayed menstrual period appeared nausea, vomiting and other early pregnancy reaction, and then carry out the test or can be appropriate to extend the examination time, can clearly diagnose the woman whether the pregnancy occurs.