A pregnancy test can be used 14 days after intercourse, or one week after the postponement of menstruation for relatively accurate test results. After intercourse, the fertilized egg secrets human chorionic gonadotropin, which is the first to reach the bloodstream and then the urine with the blood circulation, and it takes 12 days before a pregnancy test can be used to check the result. If you have irregular menstruation, it is not easy to determine the time to use the pregnancy test. Irregular menstruation will affect ovulation and the time of conception, so if you want to confirm whether you are pregnant as soon as possible, it is better to go to the hospital to have a blood test, which is more accurate. It is best to use morning urine to check early pregnancy with a pregnancy test because the concentration of human chorionic gonadotropin in morning urine is relatively high, and if the urine is diluted after drinking water, it will cause a false negative. If pregnancy is confirmed, it is recommended to conduct an ultrasound examination around 35 days of pregnancy to exclude ectopic pregnancy.