Your baby development month by month
Your Baby’s Growth: Conception to Birth
You’re pregnant. Congratulations! Are you curious how big your developing baby is, what your baby looks like as it grows inside you, and when you’ll feel it move? Take a peek inside the womb to see how a baby develops from month to month.
Fertilization happens when a sperm meets and penetrates an egg. It’s also called conception. At this moment, the genetic makeup is complete, including the sex of the baby. Within about three days after conception, the fertilized egg is dividing very fast into many cells. It passes through the fallopian tube into the uterus, where it attaches to the uterine wall. The placenta, which will nourish the baby, also starts to form.
Development at 4 Weeks
At this point the baby is developing the structures that will eventually form his face and neck. The heart and blood vessels continue to develop. And the lungs, stomach, and liver start to develop. A home pregnancy test would show positive.
Development at 8 Weeks
The baby is now a little over half an inch in size. Eyelids and ears are forming, and you can see the tip of the nose. The arms and legs are well formed. The fingers and toes grow longer and more distinct.
Development at 12 Weeks
The baby measures about 2 inches and starts to make its own movements. You may start to feel the top of your uterus above your pubic bone. Your doctor may hear the baby’s heartbeat with special instruments. The sex organs of the baby should start to become clear.
Development at 16 Weeks
The baby now measures about 4.3 to 4.6 inches and weighs about 3.5 ounces. You should be able to feel the top of your uterus about 3 inches below your belly button. The baby’s eyes can blink and the heart and blood vessels are fully formed. The baby’s fingers and toes have fingerprints.