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Week 5
Your baby now resembles a teeny tadpole and is about the size of an orange seed. The circulatory system, along with the heart, is the first part of that tiny body to be functional; and as your baby's heart starts to form, you may even be able to see it beating on an early ultrasound. Another part of your little tadpole that is under construction: the neural tube, which will eventually become your baby's brain and spinal cord.
http://www.whattoexpect.com/pregnancy/week-by-week/week-5.aspx -
Week 7
Hands and feet are emerging from developing arms and legs — although they look more like paddles at this point than the tiny, pudgy extremities you're daydreaming about holding and tickling. Technically, your baby is still considered an embryo and has something of a small tail, which is an extension of her tailbone. The tail will disappear within a few weeks, but that's the only thing getting smaller.
http://www.babycenter.com/6_your-pregnancy-7-weeks_1096.bc -
Week 9
Your baby's heart finishes dividing into four chambers, and the valves start to form — as do her tiny teeth. The embryonic "tail" is completely gone. Your baby's organs, muscles, and nerves are kicking into gear. The external sex organs are there but won't be distinguishable as male or female for another few weeks. Her eyes are fully formed, but her eyelids are fused shut and won't open until 27 weeks.
http://www.babycenter.com/6_your-pregnancy-9-weeks_1098.bc -
Week 12
Your baby's fingers will soon begin to open and close, his toes will curl, his eye muscles will clench, and his mouth will make sucking movements. His intestines, which have grown so fast that they protrude into the umbilical cord, will start to move into his abdominal cavity about now, and his kidneys will begin excreting urine into his bladder.
http://www.babycenter.com/6_your-pregnancy-12-weeks_1101.bc -
Week 15
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.
http://www.babycenter.com/6_your-pregnancy-15-weeks_1104.bc -
Week 18
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.
http://www.babycenter.com/6_your-pregnancy-18-weeks_1107.bc -
Week 22
At 11 inches (the length of a spaghetti squash) and almost 1 pound, your baby is starting to look like a miniature newborn. His lips, eyelids, and eyebrows are becoming more distinct, and he's even developing tiny tooth buds beneath his gums. His eyes have formed, but his irises (the colored part of the eye) still lack pigment.
http://www.babycenter.com/6_your-pregnancy-22-weeks_1111.bc -
Week 26
The network of nerves in your baby's ears is better developed and more sensitive than before. He may now be able to hear both your voice and your partner's as you chat with each other. He's inhaling and exhaling small amounts of amniotic fluid, which is essential for the development of his lungs. These so-called breathing movements are also good practice for when he's born and takes that first gulp of air.
http://www.babycenter.com/6_your-pregnancy-26-weeks_1115.bc -
Week 30
Your baby's about 15.7 inches long now, and she weighs almost 3 pounds (like a head of cabbage). A pint and a half of amniotic fluid surrounds her, but that volume will decrease as she gets bigger and takes up more room in your uterus. Her eyesight continues to develop, though it's not very keen; even after she's born, she'll keep her eyes closed for a good part of the day.
http://www.babycenter.com/6_your-pregnancy-30-weeks_1119.bc
http://www.babycenter.com/6_your-pregnancy-30-weeks_1119.bc -
Week 34
Your baby now weighs about 4 3/4 pounds (like your average cantaloupe) and is almost 18 inches long. Her fat layers — which will help regulate her body temperature once she's born — are filling her out, making her skin is also smoother than ever. Her central nervous system is maturing and her lungs are continuing to mature as well.
http://www.babycenter.com/6_your-pregnancy-34-weeks_1123.bc -
Week 38
Your baby has really plumped up. She weighs about 6.8 pounds and she's over 19 1/2 inches long (like a leek). She has a firm grasp, which you'll soon be able to test when you hold her hand for the first time! Her organs have matured and are ready for life outside the womb.
http://www.babycenter.com/6_your-pregnancy-38-weeks_1127.bc
