Monozygotic twins generally have a fetal heartbeat at around 17-20 weeks of gestation, but there are individual variations. Identical twins refers to monozygotic twins, which are twin pregnancies formed by the division of a fertilized egg. Generally, an ultrasound examination can detect a gestational sac and a primitive fetal heartbeat at around 17-20 weeks of pregnancy. However, depending on the length of the menstrual cycle, the time of ovulation and the time of fertilization, there may be individual differences in the time of detecting the fetal heartbeat, so if necessary, it is necessary to follow the doctor’s instructions for temporary observation and re-checking. Twin pregnancy is a high-risk pregnancy, especially monozygotic twin pregnancy, so when early pregnancy is clearly diagnosed as monozygotic twin pregnancy, and the embryo development is good, you need to strengthen the management of pregnancy, strictly comply with the doctor’s advice on time, pay attention to appropriate rest, avoid strenuous exercise and excessive exertion, increase diet and nutrition, and continue to take folic acid on time.