From Babycenter:

"How your baby's growing: Your belly may soon be big enough to announce to the world that you're expecting, but your baby is still tiny. In fact, he's only about 3 inches long crown to rump — roughly the size of a jumbo shrimp — and weighs just about an ounce. Despite the small proportions, there's a fully formed baby inside your womb now. Much more proportional than it was a few weeks ago, his head is now only about a third the size of his body. His tiny, unique fingerprints are already in place. His kidneys and urinary tract are functional, and he's starting to urinate out the amniotic fluid he's been swallowing. As you start your second trimester, most of your baby's critical development will be completed, and your odds of miscarriage will drop considerably."