At the 4th week of pregnancy an embryo begins to develop. Expectant mother may not know about her pregnancy, so the first signs of pregnancy – breast swelling, nausea, irritability and pulling sensation in the abdomen a woman perceives as harbingers of menstruation.

During the 3rd week of pregnancy a zygote was formed. Then it moved through the fallopian tubes and turned into a blastocyst. How to behave at the 4th week of pregnancy, and what future mother should expect, will be discussed in the following paragraphs.