Prenatal Development

  • week 4

    week 4
    This week marks the beginning of the embryonic period. From now until 10 weeks, all of your baby's organs will begin to develop and some will even begin to function. As a result, this is the time when she'll be most vulnerable to anything that might interfere with her development.
  • week 8

    week 8
    New this week: Webbed fingers and toes are poking out from your baby's hands and feet, his eyelids practically cover his eyes, breathing tubes extend from his throat to the branches of his developing lungs, and his "tail" is just about gone. In his brain, nerve cells are branching out to connect with one another, forming primitive neural pathways. You may be daydreaming about your baby as one sex or the other, but the external genitals still haven't developed enough to reveal whether you're havi
  • week 12

    week 12
    The most dramatic development this week: reflexes. Your baby's fingers will soon begin to open and close, his toes will curl, his eye muscles will clench, and his mouth will make sucking movements. In fact, if you prod your abdomen, your baby will squirm in response, although you won't be able to feel it. His intestines, which have grown so fast that they protrude into the umbilical cord, will start to move into his abdominal cavity about now, and his kidneys will begin excreting urine into his
  • week 16

    week 16
    Get ready for a growth spurt. In the next few weeks, your baby will double his weight and add inches to his length. Right now, he's about the size of an avocado: 4 1/2 inches long (head to rump) and 3 1/2 ounces. His legs are much more developed, his head is more erect than it has been, and his eyes have moved closer to the front of his head. His ears are close to their final position, too. The patterning of his scalp has begun, though his locks aren't recognizable yet. He's even started growing
  • week 20

    week 20
    Your baby weighs about 10 1/2 ounces now. He's also around 6 1/2 inches long from head to bottom and about 10 inches from head to heel — the length of a banana. (For the first 20 weeks, when a baby's legs are curled up against his torso and hard to measure, measurements are taken from the top of his head to his bottom — the "crown to rump" measurement. After 20 weeks, he's measured from head to toe.)
  • week 24

    week 24
    Your baby's growing steadily, having gained about 4 ounces since last week. That puts him at just over a pound. Since he's almost a foot long
  • week 28

    week 28
    By this week, your baby weighs two and a quarter pounds (like a Chinese cabbage) and measures 14.8 inches from the top of her head to her heels. She can blink her eyes, which now sport lashes
  • week 32

    week 32
    By now, your baby weighs 3.75 pounds (pick up a large jicama) and is about 16.7 inches long, taking up a lot of space in your uterus. You're gaining about a pound a week and roughly half of that goes right to your baby
  • week 34

    week 34
    Your baby now weighs about 4 3/4 pounds (like your average cantaloupe) and is almost 18 inches long. Her fat layers — which will help regulate her body temperature once she's born — are filling her out, making her rounder.
  • week 36

    week 36
    Your baby is still packing on the pounds — at the rate of about an ounce a day. She now weighs almost 6 pounds (like a crenshaw melon) and is more than 18 1/2 inches long.
  • week 40

    week 40
    •You have now reached the time of delivery.
    •All systems are developed and ready to go.
    •Now it is just a matter of time.
    •Baby is about 20 inches (51cm) and weighs approximately 7.5 pounds (3.5 kg).
    •The head has a diameter of about 4 inches (10 cm).
    •The contractions could begin at any moment.