You can find out how many babies you have at 6-8 weeks of pregnancy. If the pregnancy is too short, the pregnancy sac cannot be detected in the uterine cavity through ultrasound, and it is not possible to determine whether it is a single or multiple pregnancy. If you are 6-8 weeks pregnant, you can see the gestational sac, and the number of gestational sacs will help you to know whether it is a singleton or multiple pregnancy; only one gestational sac is probably a singleton, and two or more gestational sacs is a multiple pregnancy. Confirmation of multiple births also needs to be judged later by whether there is a fetal heart and buds in the gestational sacs, the development of buds and heart can only prove that the uterus is a live fetus, so that the normal pregnancy can continue. Twin pregnancy early pregnancy blood test HCG and progesterone, compared to a single pregnancy value is much higher, HCG value doubled every other day to grow faster, through the blood test can also be a general understanding of whether the multi-fetal pregnancy. After the pregnancy is confirmed, do a good job of pregnancy and obstetrics examination, abnormalities in time to deal with.