Prenatal Development Timeline

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  • Weeks 1-2

    Weeks 1-2
    • Not actually pregnant by OB/GYN
    • The Uterus has begun to prepare for the fertilized egg
    • During weeks and two the baby is just being conceived what to expect

  • Weeks 3-4

    Weeks 3-4
    • The heart starts to beat
    • Eyes, ears, and nose start to form
    • The neural tube starts to close and will for the brain and spinal cord Charlotte Lozier Institute

  • Weeks 5-6

    Weeks 5-6
    • Has burrowed into the wall of the uterus and is now called the embryo
    • The foundation is in place for all major organs
    • The brain and spinal cord are forming pregnancybirth&baby

  • Weeks 7-8

    Weeks 7-8
    • The brain is extremely large (about 43% of the baby's total weight)
    • The digestive system and kidneys start working
    • The embryo can produce urine and will start to pee into the amniotic fluid
    • The eyes are now developed Charlotte Lozier Institute

  • Week 11

    • Your baby is kicking but they're too small for you to feel
    • The baby's fingers and toes have lost their webbing and are now more defined
    • The baby's genitals are starting to form, but it will take several weeks to tell the gender through ultrasound
    • All of the baby's vital organs are in place
    • The four chambers of the baby's heart are fully formed baby center

  • Week 12

    Week 12
    • Toes can curl
    • Kidneys can excrete urine
    • The baby has finger and toe prints
    • Brain is continuing its fast development
    • All the baby's organs are in place and now they're beginning to grow (currently weighs about 1/2 an ounce)

  • Week 14

    • Baby may wiggle their toes and suck their thumb
    • Will start to grow peach fuzz
    • Sex of the baby is now more apparent theBUMP

  • Week 16

    Week 16
    • You may now start to feel the baby move
    • Hair follicle pattern is starting to form on the baby's head and will determine how the hair will grow for the rest of the baby's life
    • The baby is just around five ounces
    • Baby's skin is thin and transparent babycenter

  • Week 18

    Week 18
    • Baby is beginning to form myelin
    • An ultrasound can now determine the baby's sex with high accuracy
    • Baby's internal clock is developing and will take naps
    • You'll have a better chance of feeling your baby move this week verywell family

  • Week 19

    Week 19
    • The brain is developing specialized areas for the senses
    • Vernix voasa is developing on baby's skin (Vernix voasa protects the baby's skin from harmful bacteria, keeps baby's skin moisturized, and helps the lungs and digestive tract develop)
    • Baby now weighs about 10 ounces babycenter

  • Weeks 20-21

    Weeks 20-21
    • Baby's digestive system is getting prepared and making meconium
    • Baby's reproductive system is developing (if its a girl she already has all her eggs for her lifetime)
    • Baby weighs about 13 ounces
    • Baby's eyelids may now begin to open

  • Week 22

    Week 22
    • The lungs are developing and the baby will begin to try to breath
    • Baby's taste buds are developing
    • Baby is swallowing small amounts of amniotic fluid
    • Baby weighs about 15 ounces

  • Week 24

    Week 24
    • The smallest branches of the baby's lungs are growing
    • Their skin is still translucent and thin
    • They'll soon start to plump
    • Baby is now starting to experiment with facial movements babycenter

  • Weeks 31-32

    Weeks 31-32
    • Baby can hear distinct sounds and noises
    • All major organs are developed, however lungs are still premature
    • Baby now weighs about 4 pounds
    • A layer of fat is forming under baby's skin Grow by WebMD

  • Weeks 28-29

    Weeks 28-29
    • Baby's brain will triple in weight this trimester
    • Baby's autonomic nervous system is establishing breathing patterns and temperature
    • Baby is now about 2 1/2 pounds babycenter

  • Week 34

    Week 34
    • Baby can see their first color (red, because it's the first color inside the uterus)
    • Fat layers growing in baby are round him out and plumping him up
    • Baby weighs about 5 1/2 pounds
    • If the baby is born now he has a high chance of surviving unless the baby has underlying health issues babycenter

  • Weeks 36-37

    • The baby's circulatory and musculoskeletal system are fully developed but the baby's lungs, brain, and nervous system still need some time
    • Baby has moved to the head down position, readying for birth
    • Baby is very close to being ready for birth but is still maturing
    • Baby had a well developed sleep-wake cycle the BUMP verywell family

  • Weeks 37-40 (Full Term)

    Weeks 37-40 (Full Term)
    • The brain weighs about 400 grams but will continue to grow after birth
    • Baby's bones are ready for birth and ready to overlap for their trip through the cervix
    • Baby may weigh about 8 pounds at 40 weeks
    • Past 40 weeks is common for new mothers

  • Week 10

    Week 10
    • You can now hear the baby's heartbeat on a fetal Doppler
    • You can now take prenatal tests
    • Eyes are developed but the eyelids will remain shut
    • Teeth are starting to harden and connecting to the jaw bone
    • The baby's forehead will temporarily bulge for the developing brain. baby center