Pregnancy around 35-42 days through ultrasound may test how many embryos. After pregnancy through ultrasound can observe the uterine cavity there are several gestational sacs bed, observe the number of gestational sacs to understand how many babies, the usual menstrual cycle is more regular, the pregnancy around 35-42 days may be tested out. The usual menstrual cycle disorder, the fertilized egg is more late to bed, may be delayed a week before you can test out, there is also a case of ectopic pregnancy, in the uterine cavity can not be seen in the gestational sacs. Multiple births are the result of cell division. Generally, a woman will discharge one egg a month, and one egg combined with one sperm is a singleton stage. A woman who has more than one egg will combine with a sperm to form a fertilized egg, and the cells will divide, dividing into a few cells to carry a couple of twins. After the pregnancy is confirmed, do a good job of pregnancy checkups, there are abnormalities in time to deal with the treatment, so as to avoid delaying the disease.