It is usually best to check the fetal heart at 6 weeks of pregnancy, but there are individual variations and it is important to follow your doctor’s instructions. In early pregnancy, a round or oval intrauterine sac can be seen on ultrasound at 5 weeks after menopause, and fetal buds and primitive heartbeat can be seen on ultrasound at about 6 weeks after menopause. Therefore, it is generally best to check the fetal heart at 6 weeks of pregnancy, and the gestation period can be checked according to the size of the fetal buds. However, due to the influence of the menstrual cycle and the time of ovulation, there can be individual differences. For pregnant women with a long menstrual cycle, ovulation will be late, so the time of fertilized egg implantation will also be delayed, may not be able to find the fetal heart at 6 weeks of pregnancy ultrasound, but when the progesterone and blood HCG (human chorionic gonadotropin) levels are normal, you can follow the doctor’s advice about one week to repeat ultrasound, to learn about the development of the embryo and the fetal heart situation, but also to check the gestation week again.