A new stage of life
At time, the baby has graduated from embryo to fetus! All basic systems and organs are in place and continue to grow in complexity [1]. Growing bigger and bigger every week, the baby’s curved body gradually straightens — with their head not so tightly pressed to the chest. As the baby learns to lift their head, the neck is strengthened.
This week, the baby’s legs begin to catch up to the development of their arms. All joints are clearly defined and the fingers and small nails are visible. Milk teeth are developing under the gums. Baby’s musculature is getting stronger, so movements become more pronounced, although you still won’t be able to feel them. The right and left hemispheres of the brain and cerebellum continue to develop quickly.
This week, the lymphatic system is formed with the thymus gland, providing the baby with their first immune cells, called lymphocytes. These will protect the baby from foreign proteins.
Your baby is now swallowing amniotic fluid which helps aid in their development and helps the intestines to start working. The liver produces its first bile and synthesizes blood proteins; kidneys and other urinary organs also begin to function. Amniotic fluid is flushed out with urine about 10 times a day. This liquid does not contain toxic products, since the fetus uses the mother's system to excrete them.
At this time, the sex glands of boys begin to produce testosterone and the ovaries begin to produce female germ cells.
What we can see on an ultrasound
The first photograph shows a baby lying on their back surrounded by amniotic fluid. Their movements are becoming more distinct, and they are already able to push off from the uterus wall.
The baby’s head is visible and still measures about half their body. The little one’s face is clearly outlined, including nose and lips.
In the foreground, you can see the baby’s shoulder and left arm. Legs are bent and not visible from this position.
The dark spot on the chest is the heart, which already has four chambers, but venous and arterial blood are still mixed.
heart
head
hand
The following picture shows the baby’s head. A clear view of the face allows you to see the eye sockets under the eyelids, nose, lips, chin, and neck.
The head is raised and the right arm rests along the torso. Right now, the arms are longer than the legs, but they will soon catch up.
A tiny heart is visible in the chest.
the brain
heart
hand
Brewer S. The Pregnant Body Book. Dorling Kindersley Publishing Staff, 2012, p. 133.
