Theoretically, no growth of the embryo takes place until a week has passed from the time the egg has been fertilized. When fertilization takes place, the fertilized egg comes to be known as a zygote. Inside this zygote is the complete DNA material required by it to create a baby. The zygote swims along the fallopian tubes, keeping on reproducing new cells even as it makes its way. » Read more: The Embryo Stage Of Pregnancy