After the 50th day of pregnancy, an ultrasound of the fetus is performed to check the fetal heart and germ. As a rule, at 35 days of menopause, the development of the gestational sac can be seen on the earliest ultrasound. At 46-48 days of menopause, the development of the fetal heartbeat and fetal buds will be seen. If there is a delay in ovulation, after 40 days of menopause, or after 50 days, the fetal heart and germ cannot be seen on ultrasound, you can extend the time appropriately and have a waiting period. Basically, after the diameter of the gestational sac is greater than 2.5 cm, if there is still no fetal heart, consider fetal abortion. Therefore, the ultrasound check for fetal heart is usually done at more than 50 days of menopause, which is a relatively safe time period, and the fetal heart and fetal bud will appear on ultrasound, unless the menstruation is very irregular, the fetal heart will appear at more than 60 days. The above content is for reference only. Please refer to the doctor’s instructions for specific medication and treatment.