Your baby's body is straightening, looking rather like a tadpole now and his skin is transparent. A major development this week is the beginning of the circulatory system and your baby's first red blood cells are created in the liver. At seven weeks pregnancy, major organs continue to form, including brain, bladder, heart, intestines, kidneys, liver, lungs and pancreas. Primordial genitals are now present, but it's not possible to say yet whether it's a boy or a girl. The major muscles and bones are starting to develop, but movements are uncoordinated.