Unborn Baby Development at 17-20 Weeks
By the end of this month you can definitely feel your unborn baby development due to the cantaloupe-sized uterus at the level of your navel. Other growth milestones include:
1. Your baby weighs around three-quarters of a pound, and measures between 8-10 inches long. This is about half the length baby will be at birth.
2. Baby’s legs, now around the size of your little finger, continue growing, become more muscular, and make their presence felt as tiny flutter kicks.
3. He waves his growing, but still tiny, arms. On ultrasound, you may see him sucking his thumb and making a fist.
4. Baby hair is beginning to appear on his upper lid, eyebrows and head.
5. His skin, previously thin and transparent, now begins to accumulate fat deposits.
6. Baby’s oil glands start to secrete a waxy substance that mixes with his dead skin cells to form a cheesy coating, called the Vernix caseosa, which acts like a sort of wetsuit protecting the little swimmer’s skin from chapping.
7. Fine, temporary hair—called lanugo (meaning “wool”)—covers most of his body and helps to hold the vernix on the skin.
8. Baby’s digestive system functions better now, and he regularly swallows amniotic fluid and urinates into it.
9. By this month of unborn baby development, baby’s middle ear structures have formed, enabling baby to hear sound.
10. Still, baby cannot yet survive outside the womb at this stage because his lungs are still undeveloped.