Pregnancy week by week - First Trimester

After fertilization and implantation, a baby is at first just an embryo: two layers of cells from which all the organs and body parts will develop. Growing quickly, your baby is soon about the size of a kidney bean and constantly moving. The heart is beating quickly and the intestines are forming. Your budding son or daughter's earlobes, eyelids, mouth, and nose are also taking shape.

In early pregnancy your baby grows dramatically, from a tiny dot to the size of a grape.