From the Start
Fertilization marks the beginning of a new, individual life. At fertilization, the DNA of a single sperm and ovum merge to create the genetic blueprint for a new human being. Once the DNA has recombined and the single-celled ovum begins to divide, things really begin to roll.
MONTH ONE
Fertilization! The sperm and egg join in your fallopian tube to form a unique human being -- that's 46 combined chromosomes which pre-determine all of a person's physical characteristics.
Washed into your uterus, the developing embryo searches for a nice place to implant and is only one-sixth of an inch long, but growing quickly.
The heart, no larger than a poppy seed, has been beating since day 18 when you're just four days late for your menstrual period, and by 21 days it is pumping, through its own closed circulatory system, blood whose type is different from yours. Four weeks after fertilization the eye, ear and respiratory systems begin to form and thumbsucking has been photographed within the first month by scientists.