This is a babycenter.com video. A 3D animated look at baby development in the first trimester of pregnancy, including the formation of nails and fingerprints, the debut of limb movements and kicks, and the making of red blood cells and urine. Here is the transcript: At ten weeks and barely the size of a kumquat, your baby is entering the fetal stage of development. His facial features are defined, and his tooth buds are forming. Over the next weeks, his tissues and organs will rapidly grow and mature. The webbing is gone between his fingers and toes, and his nails and fingerprints are developing. Your baby can open and close his fists and curl his toes. Thanks to his developing muscles and reflexes, he's now moving his limbs and kicking up a storm. If this is your first baby, though, you likely won't feel his flutters until 18 to 20 weeks. Through translucent skin, his vital organs are visible and functioning, including his growing brain, nervous system, intestines, and liver, which is making red blood cells in place of the disappearing yolk sac. The umbilical cord is working hard now. One vein delivers oxygen and nutrient-rich blood to your baby. Two arteries then carry the blood away. Around week 12, the kidneys have begun producing urine, which your baby will soon start excreting into the amniotic fluid. He'll swallow the fluid, and the process will begin again. By week 14, your baby's eyes and ears have moved into place, and he can squint, frown, and grimace. You're now beginning the second trimester of pregnancy, which many women say is when they feel their best.