Women’s menstrual cycle is different, the time to see the fetal heart is also different, pregnancy 40 days whether there is a fetal heart to be considered in conjunction with the menstrual cycle, can be divided into the following two cases: 1, the menstrual cycle is more regular: if the menstrual cycle is regular, usually in more than 40 days of pregnancy may be able to see the fetal heart from the ultrasound under the ultrasound. Some women with shorter menstrual cycles, having a period in more than 20 days, can see the fetal heartbeat under ultrasound at 5-6 weeks of pregnancy; 2. Irregular menstrual cycles: if the menstrual cycle is usually longer, at 40-50 days, or even 2 months before the menstrual period, the time to see the fetal buds and the fetal heartbeat will be relatively late, sometimes until after 8-9 weeks or later. At 9 weeks of pregnancy the fetal heartbeat is already very obvious and can be clearly heard by the pregnant woman with a stethoscope below the navel. The absence of a fetal heartbeat beyond this number of days should be considered a case of fetal arrest, which is directly related to heredity, external infections, stimulation by reflex substances, etc., and requires extra attention in the preparation for pregnancy and the early stages of pregnancy. If there is no fetal heartbeat or the fetus has been sterilized, an abortion should be performed according to the doctor’s recommendation and pregnancy should be avoided for six months to give the uterus a chance to repair itself and prepare for the next pregnancy.