Fertilization! The sperm and egg join in your Fallopian tube to form a unique human being. That's 46 combined chromosomes which pre-determines 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. Thumb-sucking has been photographed within the first trimester, at 9 to 12 weeks, by scientists.
Did ya know?
The baby at the fetal stage savors its mother's meals, first picking up the food tastes of a culture in the womb. And you wondered why you love spicy food so much!