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Week 6
This week's major developments: The nose, mouth, and ears. His emerging ears are marked by small depressions on the sides of the head, and his arms and legs by protruding buds. His heart is beating about 100 to 160 times a minute and blood is beginning to course through his body. His intestines are developing, and the bud of tissue that will give rise to his lungs has appeared.
http://www.babycenter.com/6_your-pregnancy-6-weeks_1095.bc -
Week 9
Your new resident is nearly an inch long and weighs just a fraction of an ounce. Her essential body parts are accounted for. Other changes abound: Your baby's heart finishes dividing into four chambers, and the valves start to form — as do her tiny teeth. 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.
http://www.babycenter.com/6_your-pregnancy-9-weeks_1098.bc -
Week 12
The most dramatic development this week: reflexes. 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. Meanwhile, nerve cells are multiplying rapidly, and in your baby's brain, synapses are forming furiously.
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. The baby can now move all of its joints and is sensing light. 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. Now, you might be able to determine its sex by an ultrasound.
http://www.babycenter.com/6_your-pregnancy-15-weeks_1104.bc -
Week 18
At five and a half inches long and five ounces in weight, he now may be large enough for you to feel him kicking and punching. Plus, he's developing yawning and hiccupping skills and his own unique set of toe and fingerprints. 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.
http://www.whattoexpect.com/pregnancy/week-by-week/week-18.aspx and http://www.babycenter.com/6_your-pregnancy-18-weeks_1107.bc -
Week 21
Your baby now weighs about three-quarters of a pound and is approximately 10 1/2 inches long. Her initial fluttering movements may turn into full-fledged kicks and nudges. You may also discover a pattern to her activity as you get to know her better. In other developments, your baby's eyebrows and lids are present now, and if you're having a girl, her vagina has begun to form as well.
http://www.babycenter.com/6_your-pregnancy-21-weeks_1110.bc -
Week 24
Your baby is about eight and a half inches long and weighs one and a half pounds, gaining steadily at a rate of six ounces per week. Those ears are getting sharper and can hear very loud sounds. Also by now, the face is almost fully formed, complete with eyelashes, eyebrows, and hair. right now her locks are white since there's no pigment yet.
http://www.whattoexpect.com/pregnancy/week-by-week/week-24.aspx -
Week 27
This week, your baby weighs almost 2 pounds and is about 14 1/2 inches long with her legs extended. She's sleeping and waking at regular intervals, opening and closing her eyes, and perhaps even sucking her fingers. With more brain tissue developing, your baby's brain is very active now. While her lungs are immature, they would be capable of functioning. You may be feeling to a case of baby hiccups, which may be common from now on.
http://www.babycenter.com/6_your-pregnancy-27-weeks_1116.bc -
Week 30
The baby now weighs over three pounds. Also growing daily is his brain, which is actually starting to look like the real thing with those characteristic grooves and wrinkles. And now that your baby can regulate his own body temperature and turn up the heat, he'll start shedding lanugo, the downy body hair that's been keeping him warm up until now.
http://www.whattoexpect.com/pregnancy/week-by-week/week-30.aspx -
Week 33
This week your baby weighs a little over 4 pounds and has passed the 17-inch mark. He's rapidly losing wrinkles and his skeleton is hardening. The bones in his skull aren't fused together, which allows them to move and slightly overlap, thus making it easier for him to fit through the birth canal. These bones don't entirely fuse until early adulthood, so they can grow as his brain and other tissue expands during infancy and childhood.
http://www.babycenter.com/6_your-pregnancy-33-weeks_1122.bc
