Features of your baby:
* Your baby is approximately 2.5-3cm (1inch) in length. He/she weighs about 2g.
Circulatory System:
* Your baby's heart has been beating since the 3rd week. Blood vessels and blood cells have
begun to form.
* Fetal circulation: Blood flows from the placenta to the umbilical vein up to the underside of the
liver to the ductus venosus which spills into the inferior vena cava. From there, it heads to the right atrium of the heart
and through the foramen ovale to the left atrium through the mitral valve to the left ventricle and it is expelled through
aorta where it supplies the head, neck, and upper extremities. The blood flows into the superior vena cava to the right atrium
through the tricuspid valve to the right ventricle up through the pulmonary artery to the ductus arteriosus which dumps into
the descending aorta. The aorta carries the blood to the lower extremites and out through the umbilical ateries and back to
the placenta.
Gastrointestinal System:
* The pharynx, lower respiratory tract, esophagus, stomach, first half of the duodenum, liver, pancreas,
and the gallbladder formed in the 5th and 6th week.
Respiratory System:
* The respiratory tract began developing in the 4th week and will continue to develop until
the 17th week.
Renal System:
* The kidneys formed during the 5th week but won't function until the 9th week.
Neurological System:
* Your baby has a brain! Brain waves can be detected on an electroencephalogram as of the 8th week.
Endocrine System:
* Isn't my pancreas pretty, Mommy and Daddy? Baby has had a pancreas since the 5th week.
* He/she also has thyroid and adrenal glands.
Musculoskeletal System:
* Bones and muscles have developed from the mesoderm in the 4th week.
* The flat bones of the skull are beginning to develop.
Integumentary System:
* Your baby currently has two layers of skin cells.
* Fingers and toes are forming.
* Ears and nose are forming.
