Development of the Fetus in 21 Weeks Pregnant

At this week of your pregnancy, you are in the second trimester. Wonderful alterations are taking place in your body as well as the development of the fetus in 21 weeks pregnant is going on.

By this week, not only the essential systems are developed in your baby, but also many of them are operating now in getting ready to function on their own after the birth. By this week, your baby’s legs and arms are in the proportion.

Development of the Fetus in 21 Weeks Pregnant

Here is the fetal development of 21 weeks pregnant.


By this week, your baby is nearly 10 and a half inches long and weighs about ten to thirteen ounces.


Your baby’s eyelids and eyebrows are developed fully and the baby has the capacity to blink now.

Reproductive organs

  • If you are carrying a girl baby, her vagina and womb are formed. She will be having six million eggs in the ovaries.
  • If you are carrying a baby boy, the testes start to move down from the abdomen in this week


The baby’s skin has altered from being clear to opaque as the cells of the skin stretch and grow in the preparation for fat deposits, which will form soon beneath the skin. The baby is steadily gaining weight with the fat layers being added to the body. And also developed a white colored coat of a fatty, slick substance to protect the skin which is present in the amniotic fluid and for easy delivery.


The baby’s tongue is fully formed now and the baby’s muscles are strengthening with movement. Baby’s bones are becoming harder and baby’s movements are now much coordinated. As the muscles strengthen and the neurons connected to the baby’s brain continue to grow, the movements are becoming more coordinated. Somersaults and back flips are possible, and there is a very good practice for the baby’s arm muscles and legs.

Digestive system

The baby’s digestive system is functioning already. The small intestine is beginning to absorb the sugars.

Bone marrow

The bone marrow has commenced producing blood cells, which was done by the spleen and liver till this time.


As the baby is developing, the sleep and wake cycles begin to develop. Your baby can recognize and hear your voice and might respond to some sort of sounds.


Swallowing has become a steady activity with the baby. After the baby consumes the amniotic fluid, his/her body absorbs water and sugars that is present in the liquid, with moving the waste into the large bowel. Sugars make only the part of the baby’s nourishment and most of the nutrition is still provided through your umbilical cord and placenta.


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