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http://www.webmd.com/baby/guide/your-pregnancy-week-by-week-weeks-1-4
This week, the fertilized egg — or zygote — divides several times over to become a tiny ball of microscopic cells smaller than the period at the end of this sentence. -
http://www.webmd.com/baby/guide/your-pregnancy-week-by-week-weeks-5-8
Your baby is growing. Limb buds appear that will grow into hands and feet. Many parts continue to develop: heart, lungs, intestines, appendix, brain, spinal cord, nostrils, mouth, and eyes. -
http://www.webmd.com/baby/guide/your-pregnancy-week-by-week-weeks-9-12
It's another big growth week. When your doctor uses a Doppler stethoscope now, she can hear the rapid "swooshing" noises of the heartbeat. Your baby's genitals are developing, but the sex can't be determined yet. -
http://www.webmd.com/baby/guide/your-pregnancy-week-by-week-weeks-13-16
Your baby's body is covered by very fine hair, called lanugo, which is usually shed by birth. Eyebrows and hair on the top of the head are beginning to grow, bones are getting harder, and the baby may even be sucking his thumb. -
http://www.webmd.com/baby/guide/your-pregnancy-week-by-week-weeks-17-20
The fetus measures about 5.6 to 6.4 inches from crown to rump and weighs about 9 ounces. Your baby can hear sounds by now -- your voice, heart and your stomach growling, as well as sounds outside your body. It will cover its ears with its hands if a loud sound is made near you, and it may even become startled and "jump." The baby is moving often, too -- twisting, turning, wiggling, punching and kickin -
http://www.webmd.com/baby/guide/your-pregnancy-week-by-week-weeks-21-25?page=2
Your baby, now about in its 22nd week of development, is 8.4 inches from crown to rump and weighs about 1.2 pounds. It is starting to produce white blood cells, mostly for combating disease and infection, and may respond to your touch or sounds. If you haven't felt hiccups yet, you might feel some jerking motion now. -
http://www.webmd.com/baby/guide/your-pregnancy-week-by-week-weeks-26-30
Your baby's hands are active. Thumb-sucking calms the baby and strengthens cheek and jaw muscles. Your baby can cry now. -
http://www.webmd.com/baby/guide/your-pregnancy-week-by-week-weeks-31-34
Your baby measures about 18.9 inches long from head to toe and weighs almost 4 pounds. Baby fills almost all the space in your uterus now, but may still have enough room to do somersaults. A layer of fat is forming under your baby's skin. The baby is practicing opening his eyes and breathing. -
http://www.webmd.com/baby/guide/your-pregnancy-week-by-week-weeks-35-40
Your baby's lungs are almost fully developed. It's still building fat deposits beneath its skin to keep warm after it leaves your womb. -
http://www.webmd.com/baby/guide/your-pregnancy-week-by-week-weeks-35-40?page=2
Boys often tend to weigh a little more than girls. More lanugo falls out, but some may remain at birth on the baby's shoulders, folds of skin, and backs of ears.
