In the menstrual period coitus unexpectedly pregnant, in clinical terms there are the following two possibilities: First, this time the menstruation is not menstruation at all, but abnormal bleeding, is in the last month has been pregnant, it is recommended to do ultrasound examination, through ultrasound examination to understand the size of the gestational sac, to determine whether it is the case. Secondly, because the menstrual period is relatively long, for example, 9 or 10 days before it is clean, and the menstrual cycle is relatively short, 25 days a menstrual cycle, it is possible to get pregnant if you have intercourse in the last few days of the menstrual period. It is recommended to combine the clinical history with a comprehensive analysis, through the ultrasound examination can diagnose the number of days of intrauterine pregnancy, exactly when ovulation, can be deduced.