There are so many people who say that when they get pregnant, is the fetus telling me that they are pregnant, so they will have a series of early pregnancy reactions such as nausea, vomiting or bilateral breast swelling, and is it the effect of the child itself. Strictly speaking it is indeed possible that such a factor exists. After the yolk sac is formed by the fertilized egg, it can cause progesterone to be at a high level, which in turn can cause a series of early pregnancy reactions, nausea and vomiting. Therefore, it is the hormone level itself that affects the early pregnancy response. This hormone level to the later stages, due to the fetus itself yolk sac, in a sense can also be said that the pregnancy vomiting is the fetus is sending a message, through the hormone level to tell has been pregnant, this time must pay attention to rest well.