Fetal Development

  • Week 1

    Week 1
    The first week marks the last week of the mother's menstrual period. She has 3 trimesters of pregnancy and the egg starts at . "Fun" fatcs: Pregnancy lasts for about 266 day. Each trimester is 13 weeks.
  • Week 2

    Week 2
    To help cushion the baby, the uterus forms the endometrium upon fertilization. The egg is only 1/7th of a millimeter. On the 14th day, one egg is destined to go through the fallopian tube and has about 3 to 4 days to be fertilized. Fun facts: The egg begins to multiply and divide rapidly. To determine a baby's gender, the X or Y chromosome has to effect the 23 chromosome.
  • Week 3

    Week 3
    Once the egg is fertilized, it begins to divide and multiply and travels down to the uterus. Fun facts: the cells contain all of DNA necessary to be a child. Sperm can live for 5 days in the fallopian tubes.
  • Week 4

    Week 4
    After the egg moves to the uterus 80 hours after ovulation, impantation starts 3 days later. Fun fatcs: The egg is called a blastocyst after implantation. A new hormone is released into the mother's blood stream after the blastocyst is implanted. This hormone is hCG.
  • Week 5

    Week 5
    In week 5, amniotic fluids start to build up and the embryo starts to grow. The embryo is about 4-5 mm here. Fun facts: This is when the placenta begins to develop. Also the embryo starts to recieve oxygen and vital nutrients.
  • Week 6

    Week 6
    In this week, the heart begins to take shape and beat. Also the spinal cord begins to close. The embryo is at 1/4th of an inch. Fun facts: This is the week when the brain divides into different parts. The first blood cells start to develop as well.
  • Week 7

    Week 7
    During week 7, the arms and legs on the embryo begin to grow. The embryo doubles in size from the last week to 1/2 inch. Fun facts: The mouth opening is formed in this week. The heart begins to beats with one chanmber.
  • Week 8

    Week 8
    The embyro starts to practice moving around in the uterus. The embryo is now at 3/4 of an inch. Fun facts: The mouth and nostrils start taking shape. Along with the mouth and nostrils, the face also takes shape looking more like a human.
  • Week 9

    Week 9
    Cartilage is starting to form into bone in this week. Also the heart is completed! Fun facts: At this stage, the embryo is able to flex it's wrists and elbows. The embryo is at 30 mm at week 9.
  • Week 10

    Week 10
    The muscles in the embryo's body is almost finished developing. The fetus is at 0.9 inches or 1.2 inches. Fun facts: The neck starts to take shape. If the baby is a girl, she starts to form ovaries; if a bouy, he starts to form testicles.
  • Week 11

    Week 11
    The cartiflage begins to calcify and make bone. The brain begins to develop at this stage. The fetus is at 1.5 inches at week 11. Fun facts: The brains starts to produce 250,000+ nerve cells/minute. If the baby is a boy, he starts to produce testosterone.
  • Week 12

    Week 12
    The fetus begins to move spontaneously and involuntarily at this week. In week 12, the fetus is at 2.5 inches. Fun facts: The heart rate of the fetus is at 160 beats/minute. Kidneys are developed and starts to secrete urine.
  • Week 13

    Week 13
    At this stage, the baby produces insulin to maintain it's blood glucose levels.The fetus grows 0.5 inches from the last week to be 3 inches. Fun facts: The ribs start to form. The fetus is able to flex arms and kick its legs.
  • Week 14

    Week 14
    If the fetus is female, the ovaries start to move into place towards the pelvis. The fetus is at about 3.5 inches now. Fun facts: Hormones are creating effects in the fetus's body. From the hormones, the males develop prostate glands.
  • Week 15

    Week 15
    The bones and muscles of the fetus continue to grow at week 15. Here the fetus is at 4 or so inches. Fun facts: The baby's skin is still very thin at this stage. The baby might be able to taste the mother's meals.
  • Week 16

    Week 16
    The uterus is covered to regulate the temperature of the baby in this week. Fat begins to form underneath the skin of the baby as well. At this week, the baby is about 5 inches. Fun facts: The baby has developed its face muscles. The baby can also hear external voices and can sleep and even dream.
  • Week 17

    Week 17
    At this week, the mother's uterus is the size of a canteloup. The fetus starts to recycle amniotic fluid in the uterus. The baby is still at nearly 5 inches. Fun facts: The bone is still developing. The fat that is forming under its skin will provide the baby with warmth after birth.
  • Week 18

    Week 18
    At week 18, vernix begins to form on the baby's skin. Fun facts: The baby can react to loud noises. The baby can may be able to hear the mother's heart beating.
  • Week 19

    Week 19
    At this point, the baby's heart show be visible in an ultrasound. Fun facts: The placenta begins to develop. If the baby is a girl, she already has 6 million eggs.
  • Week 20

    Week 20
    The baby starts growing hair at this point. Now the baby is at about 7 inches. Fun facts: the baby can recognize the mother's voice. Also their senses starts to develop in their brain.
  • Week 21

    Week 21
    This week, the baby's bone marrow starts to produce blood cells. Fun facts: The placenta at this point has provided nearly all of the baby's nourishment. If the baby is a boy, the testes begin to move down from the abdomen.
  • Week 22

    Week 22
    The baby is about 11 inches long here. The baby also has a regular sleeping schedule. Fun facts: The mother's movements can wake the baby. The taste buds begin to develop.
  • Week 23

    Week 23
    The baby is still 11 inches. Their inner ear is developed which controls their balance. Fun facts: The child can now suck. The baby does regular workouts.
  • Week 24

    Week 24
    The baby is now developing the branches inside of its lungs. The baby is also a foot long now. Fun facts: The fetus can show distaste in some foods that the mom eats. When the fetus inhales, they are inhaling amniotic fluids.
  • Week 25

    Week 25
    The baby is now 13.5 inches. Its bones are becoming solid now. Fun facts: The brain is still growing. The sexual organs are completed!
  • Week 26

    Week 26
    At 26 weeks, the baby is at 14 inches. The hands start to becoming more active. Fun facts: By sucking their thumbs, the baby becomes more calm and strengthens its jaw muscles and cheeks. The baby's eyes also start to open now
  • Week 27

    Week 27
    Now at 14.5 inches long, the baby continues to develop their hearing and can open and blink their eyes. Fun facts: During this time, the baby's body is getting more plump. Their brain still continues to develop.
  • Week 28

    Week 28
    The fetus has its own sleeping pattern and is 14.5 inches long. Also their teeth have developed underneath the gums. Fun facts: The eyes are able to move in their sockets at this time.Their hair is visible now.
  • Week 29

    Week 29
    The fetus is around 15 inches long. And in the brain billions of neurons are being developed. Also the muscles and lungs are continuing to develop. Fun fact: The fetus can respond to pain. The head grows bigger for the brain.
  • Week 30

    Week 30
    The Baby measures around 16 inches, Their wrinkled skin is becoming smoother now. The boys testicles have begun to moved down to the groin. Lastly, the baby controls its own body temperature.Fun fact: Nourishment is tranferred through the mothers blood to the placenta and throught the umbilical cord. The hands are now fully formed.
  • Week 31

    Week 31
    The baby is 16.5 inches and their eyes have now completely opened. They are able to respond to light and darkness. Fun fact: a loud noise near the mom can startle the baby. Almost all of the major organs are functioning.
  • Week 32

    Week 32
    The baby is 17 inches long. Underneath their skin, the fat layer is has begun to thicken. In boys, their testicles will drop from the groin down into his scrotum. Fun fact:The baby sleeps most of the day now. Kocks may be less forceful due to space.
  • Week 33

    Week 33
    The baby is now around 17.5 inches. The baby may drink about a pint of amniotic fluid a day. Fun fact: Half of the weight a woman gains will go directly to the baby. Calcium intake is extremely important during pregnancy.
  • Week 34

    Week 34
    The baby is around 18 inches long. Fat will collect around the arms and legs as the eyes open when they're awake and closed when sleeping. Fun facts: Contractions might be more common. The skull bones are more flexible.
  • Week 35

    Week 35
    The baby is now 18.5 inches in length. And the lungs are almost fully developed. Fun facts: Their reflexes are coordinated. Some babies gain about 1/2 lbs per week in the last month.
  • Week 36

    Week 36
    The baby is about 19 inches long. Its body is becoming chubby due to the fat. Fun facts: From this point and until birth the baby may gain about an ounce a day. The baby may be dropping into the birth canal.
  • Week 37

    Week 37
    Typically, a baby will measure 19.5 inches long. The baby is ready and the mothers water can break any moment. Fun facts: The baby's head is over 3.5 inches in diameter.
  • Week 38

    Week 38
    Baby is about 20 inches and the body fat is continuing to build up. The baby is ready for birth. Fun facts: Most babies are born with the head first. Development is complete!
  • Week 39

    Week 39
    The baby is around 20 inches.Its reached its final birth position and is ready for birth. Fun facts: The average baby weighs over 7 pounds.
  • Week 40

    Week 40
    Baby is born! "Fun" fact: It hurts to give birth. Contractions aren't too great either. Bonus fun fact: This almost makes me not want to have children.