5 Weeks Today...

Your pregnancy: 5 weeks

Your little embryo, which at this point resembles a tadpole more than a baby (complete with teeny tail), is growing fast and furious and is now about the size of an orange seed-still small, but a lot bigger than it's been.  This week, the heart is starting to take shape.  In fact, the circulatory system, along with the heart, is the first system to be operational.  Your baby's heart (about the size of a poppy seed) is made up of two tiny channels called heart tubes-and though it's still far from fully functional, it's already beating-something you might be able to see on an early ultrasound.  Also in the works is the neural tube, which will eventually become your baby's brain and spinal cord.  Right now the neural tube is open, but it will close by next week.

Murkoff, Heidi and Sharon Mazel. What to Expect When Your Expecting Fourth Edition. New York: Workman Publishing Co., Inc., 2008