Week 5 - A little seasame seed

How Big is the Baby at Five Weeks Pregnant?
Pregnancy week 5 isn't much different from pregnancy week 4. During 5 weeks pregnant your baby is still just over a millimeter long. You might say that your baby is about the size of a small grain of rice! However your baby is growing in many other ways. Vital organs continue to develop through this week.

Your Baby's Growth and Development
During the early part of this pregnancy at 5 weeks the central nervous system, muscles, bones and even the heart will begin to form. Early skeletal development is also possible at or around pregnancy week 5. Remember that every person is unique, thus their baby will develop at a different rate from others.

Perhaps the most interesting changes that are occurring during 5 weeks pregnant include those happening in the heart. During this week the heart will begin to divide into separate chambers and start pumping blood. The heart is formed from the middle layer of cells called the mesoderm. Other organs that will develop from this layer include the muscles, cartilage and bone. The primitive placenta and umbilical cord are also developing. The neural tube starts developing in the top layer of cells called the ectoderm. The skin, hair, nails and sweat glands will also develop out of this layer of cells. The lungs, intestines, thyroid and pancreas also develop from a third layer of cells called the endoderm.