An 8 week pregnancy checkup for a single fetus usually doesn’t turn back into twins, a single fetus is a single fetus. There is also a possibility that the pre-check did not find another embryo this possibility.
1. In the 5th, 10th and 14th days after fertilization, it may happen that 1 fertilized egg or embryo differentiates and develops into 2 fertilized eggs or embryos, and if it has not been separated on the 14th day after fertilization, this embryo can not be turned into 2 embryos, and a single fetus is a single fetus.
2. 8 weeks of pregnancy fetus has developed and formed in the uterus, this time the examination is a single fetus, it will not be from a single fetus and then become twins, unless it is the result of the previous examination is wrong, it is possible that the twins are seen as a single fetus.
After pregnancy through the ultrasound examination can be found two buds, fetal heart can be determined to be twins, only one bud, fetal heart is a single child, the specific consult a doctor to understand.