Development timeline

Timeline created by dreyes81
  • Week 1

    Week 1
    Week one is when your body is getting ready for pregnancy, and there's still no baby forming.
  • Week 2

    Week 2
    This week you start to ovulate. The egg is fertilized 12 to 24 hours later if sperm penetrates. Over the next days, cells begin to multiply which begins the journey of growing a life.
  • Week 3

    Week 3
    Nestled in the nutrient-rich lining of the uterus, a ball, called a blastocyst, of hundreds of multiplying cells that well develop into the baby.
  • Week 4

    Week 4
    The ball of cells is now an embryo. This week it is possible you might get positive for a home pregnancy test. The baby is the size of a poppy seed.
  • Week 5

    Week 5
    The baby resembles a tadpole more than a human, but it is growing fast. The circulatory system is beginning to form. The heart begins to form this week. The baby is the size of a sesame seed.
  • Week 6

    Week 6
    Your baby's nose, mouth, and ears are starting to take shape, and the intestines and brain are beginning to develop. Baby is the size of a lentil.
  • Week 7

    Week 7
    The baby has doubled the size since last week. The baby still has a tail but will disappear soon. The feet and hands are beginning to form.
  • Week 8

    Week 8
    The baby has started moving around, though you won't feel movement yet. Nerve cells are branching out, forming primitive neural pathways. Breathing tubes now extend from his throat to his developing lungs. The baby is the size of a blueberry.
  • Week 9

    Week 9
    The baby's basic physiology is in place (she even has tiny earlobes), but there's much more to come. Her embryonic tail has disappeared. She weighs just a fraction of an ounce but is about to start gaining weight fast. The baby is the size of a grape.
  • Week 10

    Week 10
    The embryo has completed the most critical portion of the development. His skin is still translucent, but his tiny limbs can bend and fine details like nails are starting to form. The baby is the size of a kumquat.
  • Week 11

    Week 11
    The baby is almost fully formed. She's kicking, stretching, and even hiccupping as her diaphragm develops, although you can't feel any activity yet. The baby is the size of a fig.
  • Week 12

    Week 12
    This week your baby's reflexes kick in: His fingers will soon begin to open and close, toes will curl, and his mouth will make sucking movements. He'll feel it if you gently poke your tummy – though you won't feel his movements yet. The baby is the size of a lime.
  • Week 13

    Week 13
    This is the last week of your first trimester. Your baby's tiny fingers now have fingerprints, and her veins and organs are clearly visible through her skin. If you're having a girl, her ovaries contain more than 2 million eggs. The baby is the size of a pea pod.
  • week 14

    week 14
    Your baby's brain impulses have begun to fire and he's using his facial muscles. His kidneys are working now, too. If you have an ultrasound, you may even see him sucking his thumb. The baby is the size of a lemon.
  • Week 15

    Week 15
    Your baby's eyelids are still fused shut, but she can sense light. If you shine a flashlight on your tummy, she'll move away from the beam. Ultrasounds done this week may reveal your baby's sex. The baby is the size of an apple.
  • Week 16

    Week 16
    The patterning on your baby's scalp has begun, though the hair isn't visible yet. His legs are more developed – find out when you're likely to feel your baby kick! His head is more upright, and his ears are close to their final position. The baby is the size of an avocado.
  • Week 17

    Week 17
    Your baby can move her joints, and her skeleton – formerly soft cartilage – is now hardening to the bone. The umbilical cord is growing stronger and thicker. The baby is the size of a turnip.
  • Week 18

    Week 18
    Your baby is flexing his arms and legs, and you may be able to feel those movements. Internally, a protective coating of myelin is forming around his nerves. The baby is the size of bell pepper.
  • week 19

    week 19
    Your baby's senses – smell, vision, touch, taste, and hearing – are developing and she may be able to hear your voice. Talk, sing or read out loud to her, if you feel like it. The baby is the size of an heirloom tomato.
  • Week 20

    Week 20
    Your baby can swallow now and his digestive system is producing meconium, the dark, sticky goo that he'll pass in his first poop – either in his diaper or in the womb during delivery. The baby is the size of a banana.
  • Week 21

    Week 21
    Your baby's movements have gone from flutters to full-on kicks and jabs against the walls of your womb. You may start to notice patterns as you become more familiar with her activity. The baby is the size of a carrot.
  • Week 22

    Week 22
    Your baby now looks almost like a miniature newborn. Features such as lips and eyebrows are more distinct, but the pigment that will color his eyes isn't present yet. The baby is the size of spaghetti squash.
  • Week 23

    Week 23
    Your baby's ears are getting better at picking up sounds. After birth, she may recognize some noises outside the womb that she's hearing inside now. The baby is the size of a large mango.
  • Week 24

    Week 24
    Your baby cuts a pretty long and lean figure, but chubbier times are coming. His skin is still thin and translucent, but that will begin to change soon too. The baby is the size of an ear of corn.
  • Week 25

    Week 25
    Your baby's wrinkled skin is starting to fill out with baby fat, making her look more like a newborn. Her hair is beginning to come in, and it has color and texture. Your baby is now the same weight as average rutabaga.
  • Week 26

    Week 26
    Your baby is now inhaling and exhaling amniotic fluid, which helps develop his lungs. These breathing movements are good practice for that first breath of air at birth. Your baby is the size of a bunch of scallions.
  • Week 27

    Week 27
    This is the last week of your second trimester. Your baby now sleeps and wakes on a regular schedule, and her brain is very active. Her lungs aren't fully formed, but they could function outside the womb with medical help. Your baby is the size of a head of cauliflower.
  • Week 28

    Week 28
    Your baby's eyesight is developing, which may enable her to sense light filtering in from the outside. She can blink, and her eyelashes have grown in. Your baby is the size of a large eggplant.
  • Week 29

    Week 29
    Your baby's muscles and lungs are busy getting ready to function in the outside world, and his head is growing to make room for his developing brain. Your baby is the size of a butternut squash.
  • Week 30

    Week 30
    Your baby is surrounded by a pint and a half of amniotic fluid, although there will be less of it as she grows and claims more space inside your uterus. Your baby is the size of a large cabbage.
  • Week 31

    Week 31
    Your baby can now turn his head from side to side. A protective layer of fat is accumulating under his skin, filling out his arms and legs. Your baby is the size of a coconut.
  • Week 32

    Week 32
    You're probably gaining about a pound a week. Half of that goes straight to your baby, who will gain one-third to half her birth weight in the next seven weeks in preparation for life outside the womb. Your baby is the size of a large jicama.
  • Week 33

    Week 33
    The bones in your baby's skull aren't fused yet. That allows them to shift as his head squeezes through the birth canal. They won't fully fuse until adulthood. Your baby is the size of a pineapple.
  • Week 34

    Week 34
    Your baby's central nervous system is maturing, as are her lungs. Babies born between 34 and 37 weeks who have no other health problems usually do well in the long run. Your baby is the size of a cantaloupe.
  • Week 35

    Week 35
    It's getting snug inside your womb! Your baby's kidneys are fully developed, and his liver can process some waste products.
    Your baby is the size of a honeydew melon.
  • Week 36

    Week 36
    Your baby is gaining about an ounce a day. She's also losing most of the fine down that covered her body, along with the vernix casosa, a waxy substance that was protecting her skin until now.
    Your baby is the size of a head of romaine lettuce.
  • Week 37

    Week 37
    Your due date is very close, but though your baby looks like a newborn, he isn't quite ready for the outside world. Over the next two weeks his lungs and brain will fully mature. Your baby is the size of a bunch of Swiss chard.
  • Week 38

    Week 38
    Are you curious about your baby's eye color? Her irises are not fully pigmented, so if she's born with blue eyes, they could change to a darker color up until she's about a year old. Your baby is the size of a leek.