Timeline of Fetal Development
By: Bethany Hubbard
*1ST TRIMESTER BEGINS
Your baby is a ball of cells, also known as a "blastocyst". However, this ball of cells already contains the DNA that determines the baby's eye color, hair, personality traits, etc.
The baby's heart has begun to beat. Additionally, facial features, eyes for example, are beginning to form, and little buds appear - where arms and legs will soon develop.
The embryo at this point is a fetus. The baby's vital organs are functioning and the baby's bones are beginning to harden. You will be able to hear your baby's heartbeat at a prenatal checkup and your baby weighs about 1/2 an ounce.
*2ND TRIMESTER BEGINS
Your baby can detect light that filters from outside the womb. At this point, your baby's kidneys are fully functioning and are releasing urine into the amniotic sac. The sex of your baby can be determined at an ultrasound.
Your baby is able to hear your heartbeat and sounds that come from outside your body, a voice talking to you for example. During the 20 week mark, you may feel your baby move significantly as this is the time period where it begins to squirm around.
Your baby's sense of motion has developed, so he or she knows when you are up and walking. Additionally, your taste buds are developing. The baby's brain is growing very quickly and your baby may even have hair.
*Third trimester begins
Your baby can begin to have it's own dreams. It has eyelashes and has been doing "practice breathing" by inhaling and exhaling the amniotic fluid that surrounds it. The baby's lungs are 99% formed and could function on their own if it was born now.
Your baby has grown fingernails and toenails. If your baby was born now, it would most likely be fine, however would need to spend some extra time in the NICU.
Your baby is now considered "full-term" as most babies are born between the 36-40 week period. Ideally however, your baby would stay a week or two more.
Your baby has hit it's due-date and is fully ready for life outside the womb. The average weight of a newborn is 7.5 pounds.