5 Weeks Pregnant

In week 5, Baby's still just an embryo, but it's growing more furiously and changing more rapidly than it will at any other time in its life! Your baby's forming a "C" shape, sort of like elbow macaroni. This tiny tube-shaped being already has a head, back, front, and... tail. (Don't worry, the tail gets absorbed into the body.) At the beginning of this week, the embryo already has 125,000 cells—enough to fill every seat in two NFL football stadiums. Even more amazingly, the baby's tiny heart has already formed, and will have started to beat (though these heart contractions won't become regular for a few more weeks). The baby's spinal cord and brain are beginning to form, as are key organs—including the lungs, liver, and pancreas—and the placenta, which that will supply your baby with oxygen and nourishment.