How big is baby?

Already a busy little bee, your developing embryo now has three layers. The outer layer, or ectoderm, will develop into the nervous system, while the endoderm, or inner layer, will become the liver, pancreas, intestines, and bladder. This week, the mesoderm, or middle layer, is developing into the heart and circulatory system, which will be the first organs to function. In the weeks to come, the mesoderm will also form the bones, muscles, kidneys and reproductive organs.
Hold onto your--breasts! If they don't feel sore yet, chances are they will in another few days. For many women, breast tenderness is the first physical sign of pregnancy. Other symptoms include fatigue, nausea, bloating, and, less commonly at this stage, a craving for foods containing salt, iron, or vitamin C.