All measurements are approximate. Click here to see how we calculate baby's length and weight.
Baby:
Your baby is about the size of a blueberry. Baby is C-shaped, with a large head at one end and a tail at the other, more closely resembling a shrimp than a person at this point!
Because of this curled-up position, the embryo can’t be measured head-to-toe yet (especially considering that there aren’t any toes — much less legs — yet!). Instead, measure the length from the top of the head to the seat — the crown-rump-length, or CRL. This is the measurement we use on these pages.
Meanwhile, tiny circles which will eventually become eyes are forming on the sides of baby’s head, as are ears. Cells that will develop into the liver, lungs, stomach and pancreas are settling into place. The liver cells will start forming the organ first. Also toward the end of this week, little arms and leg buds emerge.
Another major step this week: The heart fills with blood. It has been pumping fluid, but now there’s actual blood circulating in those tiny veins. As blood cells are formed in the wall of the yolk sac, veins quickly develop to supply the organs with nutrients.
Arteries also form this week and the heart now consists of a left and right chamber, as baby’s pulse reaches 100 to 120 beats per minute.
Blood is pumped through the connecting stalk which will become the umbilical cord so the embryo can eliminate waste material and receive nutrients from the mother. This circulation will continue until the child is born.
Mom:
Everybody’s talking about hormones! It seems like they’re the scapegoat for every mood swing and bump and turn in an expectant mother’s behavior. Of course, this truth is usually much more complicated — there are all kinds of emotional as well as physical transformations taking place.
Scapegoat or not, hormones are certainly important to pregnancy. But what exactly are they? The word hormone itself comes from the Latin word for “stir up” or “rise,” and they are, in fact, chemical substances that stimulate or regulate the functions of every part of the body. During pregnancy, hormones are vital. So the next time someone says, “Oh, that must be the hormones,” you can say, “Yup. Aren’t they great?”