Fetal Development

  • Week 1

    Week 1
    During the first week of fetal development your period is coming to an end. The official start of your pregnancy is usually determined by the first day of menstrural bleeding.
  • Week 2

    Week 2
    In week two, ovulation occurs and the sperm is then able to fertilize the egg in the fallopian tube. The fertilized egg then starts to divide and head down towards the uterus.
  • Week 3

    Week 3
    In week three the fertilized egg continues to divide and head toward the uterus. Also the gender and features of the baby are determined when the egg is fertilized.
  • Week 4

    Week 4
    In week four the fertilized egg becomes a blastocyst ( a cluster of 50-60 cells) and attaches to the uterus. After the blastocyst has implanted in the uterus ,it releases hCG (human gonadotropin hormone) into the bloodstream.
  • Week 5

    Week 5
    In week 5, the baby's amniotic sac, amniotic cavity, yolk sac, and placenta begin to develop. Half of the cells in the blastocyst will be devoted to nourishing the baby, while the other half of the cells create the baby.
  • Week 6

    Week 6
    In week 6, all the major organs of the baby begin to develop, and the placenta starts to nourish and give it oxygen. During this week women can also experience nasuea and light headedness due to the rise in hormones.
  • Week 7

    Week 7
    During week seven, the heart of the embryo starts to beat. Also the arms and legs of the baby begin to develop along with the major organs.
  • Week 8

    Week 8
    In week eight, the baby starts to develop it's pituitary gland and muscle fibers. Also the baby's facial features, such as the mouth and tounge become visible.
  • Week 9

    Week 9
    In week nine, the fingers and toes of the baby begin to develop; and it can now flex its elbows and wrists. Also during this week, the baby's head may appear larger than it's body due to the rapid growth of it's brain.
  • Week 10

    Week 10
    In week ten, the baby becomes a fetus and all of its organs, nerves, and muscles begin to function within its body. During this week of development the fetus is about the size of a strawberry.,
  • Week 11

    Week 11
    By week eleven, the baby has begun developing ears, toes, an upper lip, and twenty teeth. Also during this week the genitals of the baby have begun to develop.
  • Week 12

    Week 12
    By week twelve,the baby's facial profile, brain, and vocal cords are fully developed. Also by this week you'll be able to hear your baby's heartbeat.
  • Week 13

    Week 13
    By week thirteen, the baby has grown to about 3 inches and is now able to produce insulin to control its blood glucose.
  • Week 14

    Week 14
    During week four-teen the baby will have a prostate gland or ovaries depending on the gender of the baby. Also by this week your uterus will weigh about five pounds.
  • Week 15

    Week 15
    During the fifteenth week the bones and muscles of the baby continue to grow, and by the end of the week it'll have functioning taste buds.
  • Week 16

    Week 16
    By week sixteen the baby has learned to breath and its facial expressions are more defined. Also by breathing in the amniotic fluid, the baby is able to help its lungs develop.
  • Week 17

    Week 17
    During week seventeen the baby starts to develop fat under its skin to keep it warm, and full of energy. Also the catilage in the baby's body now begins to transform into bone.
  • Week 18

    Week 18
    During week eighteen,a protective substance called vernix starts to form on top of the baby's skin along with the lanugo.Also alveoli begin to form within the baby's lungs.
  • Week 19

    Week 19
    During week nineteen the baby's reproductive organs start to develop and fall in place. Also by this week, the baby is about 6.5 inches.
  • Week 20

    Week 20
    During week twenty, the midpoint of your pregnancy, the baby is about seven inches long and weighs about eleven ounces. From this point onward the baby reacts to sounds outside the womb and can even recognize the voice of its own mother.
  • Week 21

    Week 21
    In week twenty-one the bone marrow of the baby starts to create blood cells instead of its liver and spleen. Also the baby starts to absorb sugar from the amniotic fluid it swallows.
  • Week 22

    Week 22
    During week twenty-two the eyebrows, eyelids and fingernails of the baby are fully developed. Being aware of sounds around it, a loud noise can wake the baby inside the womb.
  • Week 23

    Week 23
    By week twenty-three the baby can turn side to side inside the womb; also skin pigment starts to form in the baby.
  • Week 24

    Week 24
    During the twenty-fouth week the baby start to develop branches in its lungs, and also cells called sufucants that help inflate the air sacs within the lungs.
  • Week 25

    Week 25
    During the twenty-fifth week the baby's spine begins to develop along with its blood vessels and lungs. Also during this time the brain cells of the baby begin to mature.
  • Week 26

    Week 26
    By week twenty-six the baby has muscle coordination and has now atarted breathing movements.Also during this week the baby's eyes will begin to open.
  • Week 27

    Week 27
    During the twenty-seventh week, otherwise known as the third trimester, the baby now has eyebrows, eyelashes, and a head of hair. Also at this point the baby can fully open its eyes.
  • Week 28

    Week 28
    During the twenty-eith week, the baby may start dreaming for the first time. During this week the eye color of the baby may change too.
  • Week 29

    Week 29
    During week twenty-nine the baby's head, muscles, and lungs are still growing. Also the baby may start to move more because as it grows, it gets more cramped.
  • Week 30

    Week 30
    During week thirty the baby starts storing phosphorus, iron, and calcium. From this week until week thirty-eight, the baby will gain about half a pound of fat a week.
  • Week 31

    Week 31
    In week thirty-one, almost all the major organs within the baby's body will be fully functioning. Also the fat and muscle of the baby will continue to grow.
  • Week 32

    Week 32
    During week thirty-two the baby will be asleep for most of the day. Also movement from the baby will subside because of the lack of room in the uterus.
  • Week 33

    Week 33
    In week thirty-three, the lanugo surrounding the baby starts to dissapear and become replaced by hair. Also the baby can drink a pint of amniotic fluid a day while practing its breathing.
  • Week 34

    Week 34
    During week thirty-four, fat accumulates especially around the baby's arms and legs. Also during this time the baby's skin becomes less wrinkled.
  • Week 35

    Week 35
    By week thirty-five, the baby's lungs are almost fully developed and its reflexes are fully functioning. About 90% of the babies born during this week survive.
  • Week 36

    Week 36
    During week thirty-six the baby "drops" into the birth canal and gets into it's birth position. When the baby drops into the birth position it may cause you to use the bathroom more frequently because the baby sits on top of your bladder during this time.
  • Week 37

    Week 37
    At week thirty-seven, you are 'at term' and ready to give birth to a healthy child. But until that point, the baby gains about one ounce of fat a day.
  • Week 38

    Week 38
    By week thirty eight, the baby's development is complete and its main focus is to gain more weight. During this week, the baby will also start to swallow the lanugo covering its body and store it in its bowels.
  • Week 39

    Week 39
    During week thirty-nine, the baby reaches its final birth position and weighs about seven and a half pounds. By this point, the lanugo that once surrounded the baby has now disappeared.
  • Week 40

    Week 40
    At week fourty, the baby is now at full term and ready to be delivered. Contractions could happen at any time during this week, or even a week from now. But when the baby is delivered, it'll weigh about six to nine pounds.