18 Weeks Yesterday!

18 WEEKS - Head to rump, your baby is about 5 1/2 inches long (about the length of a bell pepper) and he weighs almost 7 ounces. He's busy flexing his arms and legs — movements that you'll start noticing more and more in the weeks ahead. His blood vessels are visible through his thin skin, and his ears are now in their final position, although they're still standing out from his head a bit. A protective covering of myelin is beginning to form around his nerves, a process that will continue for a year after he's born. If you're having a girl, her uterus and fallopian tubes are formed and in place. If you're having a boy, his genitals are noticeable now, but he may hide them from you during an ultrasound.

17 WEEKS - Your baby's skeleton is changing from soft cartilage to bone, and the umbilical cord — her lifeline to the placenta — is growing stronger and thicker. Your baby weighs 5 ounces now (about as much as a turnip), and she's around 5 inches long from head to bottom. She can move her joints, and her sweat glands are starting to develop.

16 WEEKS - Get ready for a growth spurt. In the next few weeks, your baby will double his weight and add inches to his length. Right now, he's about the size of an avocado: 4 1/2 inches long (head to rump) and 3 1/2 ounces. His legs are much more developed, his head is more erect than it has been, and his eyes have moved closer to the front of his head. His ears are close to their final position, too. The patterning of his scalp has begun, though his locks aren't recognizable yet. He's even started growing toenails. And there's a lot happening inside as well. For example, his heart is now pumping about 25 quarts of blood each day, and this amount will continue to increase as your baby continues to develop.

15 WEEKS - Your growing baby now measures about 4 inches long, crown to rump, and weighs in at about 2 1/2 ounces (about the size of an apple). She's busy moving amniotic fluid through her nose and upper respiratory tract, which helps the primitive air sacs in her lungs begin to develop. Her legs are growing longer than her arms now, and she can move all of her joints and limbs. Although her eyelids are still fused shut, she can sense light. If you shine a flashlight at your tummy, for instance, she's likely to move away from the beam. There's not much for your baby to taste at this point, but she is forming taste buds. Finally, if you have an ultrasound this week, you may be able to find out whether your baby's a boy or a girl! (Don't be too disappointed if it remains a mystery, though. Nailing down your baby's sex depends on the clarity of the picture and on your baby's position. He or she may be modestly curled up or turned in such a way as to "hide the goods.")