Usually at 6-10 weeks of pregnancy, ultrasound can determine chorionicity by the number of gestational sacs in the uterine cavity. If there are two gestational sacs in the uterine cavity, it is a double chorionic twin, which is often referred to as heterozygous twin; if there is only one gestational sac it is a single chorionic twin, which is often referred to as homozygous twin. Homozygous twins are two fetuses formed by the division of a fertilized egg with the same genes; they have the same sex, blood type and appearance. Heterozygous twins, on the other hand, are two fetuses formed from two separate fertilized eggs with different genes, and it is possible for the two fetuses to have different blood types and genders. Pregnant women need to eat more food rich in protein during pregnancy, such as eggs, lean pork, soy products, milk and so on. It is also necessary to properly supplement shrimp, fish, pork liver, oats, walnuts, peanuts and other foods, eat more fresh vegetables and fruits to ensure that the intake of food nutritionally balanced, to avoid single nutrition. It is recommended that pregnant women with two fetuses should take pregnancy tests on time, and if symptoms of abdominal pain and vaginal bleeding occur, it is recommended that they seek medical attention in a timely manner, under the guidance of the doctor, improve the relevant examinations, clarify the cause of the disease, and provide symptomatic treatment.