Week 40

Fetal Development

  • Week 1

    Week 1
    The beginning of week one of pregnancy consists of the last day of the last menstrual period. The first day begins on the very first day that your period is supposed to come. This day is before fertalization.
  • Week 2

    Week 2
    This marks the initial start of fertalization within the Fallopian Tubes. The ovum continues with cell division as it makes its way towards the uterus.
  • Week 3

    Week 3
    The sex of the fetus has been predetermined thanks to the X or Y chromosome carried by the sperm. The child's DNA starts to form within the various amounts of divisions it goes thorugh up until it reaches 46 chromosomes. Three days later the egg implants itself into the uterin lining.
  • Week 4

    Week 4
    At this stage the fertalized egg is called a blastocyst. The embryo is only 1/100 of an inch, about the size of a poppy seed. Identical twins can be produced during this stage almost fourteen days after conception. Once this blastocyst has implanted in the uterus, hCG is release within the blood stream which gives indications of pregnancy.
  • Week 5

    Week 5
    This marks the second month of pregnancy! The fetus is about the size of a sesame seed, 2mm. The amnitoic sack is being developed along with th eplacenta. The embryo has started receiving oxygen and nutrients from the developing placenta. During this time some spotting may occur that is commonly mistaken for the first day of the mentrual period even though this bleeding occurs from the implantaion of the embryo.
  • Week 6

    Week 6
    The fetus is about 8mm long and is about the size of a lentil. The fetus has begun to develop the basic characteristics such as ears, nose, mouth, eyes. The fetus has also developed heart that resembles a pipe that beats 100-160 in a minute, thus the heart beat can be detected. Blood cells and blood vessels have started to form along with buds as arms and legs. The brain has started to form into five parts and the pituitary gland has started to form. The spinal cord tube has been shut.
  • Week 7

    Week 7
    The fetus is about 13mm in length, about the size of a blueberry. The arms adn legs have started to form along with paddles as hands and feet. The lungs, liver, pancreas and thyroid gland have all started to form a long with a dividing wall within the heart. Lenses around the eyes have started to develop to cover the entire eye.
  • Week 8

    Week 8
    The fetus is about the size of a kidney bean, 18mm. While in the womb the baby has begun to move around with the underdeveloped limbs. Teeth have began to develop underneath the gums in the mouth, along with facial features. The fetus has also developed its own blood type that has started flowing through the body.
  • Week 9

    Week 9
    The fetus has grown to be 30mm long, as big as a grape. Finger and toes are identifiable and cartilage and bones have begun to form. The main structure of the heart is complete and the larynx and tounge have began to develop. During this time the baby's head is much larger than the rest of its body because the brain is developing so rapidly.
  • Week 10

    Week 10
    The neck has began to develop along with nipples and follicales. Fingerprints have already been developed anda re able to be identified. The muscles are almost all developed but the baby still has axis to move and stretch his joints. The fetus is about the size of a kumaquat.
  • Week 11

    Week 11
    The fetus' hands and toes have completley separated and has started to develop taste buds. Everything is sesitive to touch except the tongue and the baby can stick his or her tongue out. The sex characteristics have satrted to form, if a boy testosterone levels will start to produce and the genitailia will start to form but is too early to tell the sex of the baby. Baby has developed 20 milk teeth underneath the gums. The baby is 35mm.
  • Week 12

    Week 12
    The fetus is approximatley 6cm in length and has developed full facial chracteristics. Finger nails and toenails have formed and the baby is able to suck its own thumb along with get the hiccups. Kidneys have begun to develop and secrete urine. The fetus is able to cry because the vocal chords have been developed and the fetus can feel pain.
  • Week 13

    Week 13
    The fetus has grown to be 3 inches and weighs about 1 ounce. Bone has started to replace the spongey cartilage in the body and the ribcage has started to form. The sex may be distingusihable through an ultrasound. The hormone insulin has been producing. The uterus starts to elongate within the abdomen and starts to sit on top of the pelvic bone.
  • Week 14

    Week 14
    This week marks the beginning of the second trimester! The fetus is about 3.5 inches and the eyes have moved towards the center of the face. The cheekbones are prominant, along with hair on the head. If the fetus is a girl the ovaries drop towards the pelvis, for males the prostate gland begins to develop. While the amniotic fluid builds up the baby pees in the womb and the skin still remains transparent. The fetus is about the size of a lemon.
  • Week 15

    Week 15
    The baby is about 4 inches and weighs about 2.5 ounces. The bones and muscles are still developing and the baby moves around. During this time some movement may be detected. The baby is able to breath in and out. By the end of the week the baby will have growth of bones in his or her ears along with the roof of the mouth being fully developed.
  • Week 16

    Week 16
    The fetus is about 5inches and 3.5 ounces. The fetus is still covered in a protective layering of hair known as down and fat begins to grow under the skin. Because the ears are formed the fetus can hear external sounds like the mother's voice and other things.
  • Week 17

    Week 17
    During this time the fetus' umbilical cord has grown stronger and thicker. The fetu's retinas are sensitive to light leaving their eyes to be closed. Bowel movements have started to form.
  • Week 18

    Week 18
    The fetus is about 6 inches long and weighs about 7 ounces. They are able to recognize outside the womb and may even be startled by them. It is now identifiable when there is a resting period and an active period. A wax like layer cover the fetus' body and the alveoli in the lungs start to form.
  • Week 19

    Week 19
    The fetus is about 6.5 inches and 9 ounces. The genitals are distinct and recognizable. If the child is a girl, the vagina, fallopian tubes and uterus are in place along with the 6 million eggs within her ovaries.
  • Week 20

    Week 20
    The fetus is about 7 inches 11 ounces. The first fetal movements may be felt and the heart beat can be recognized through a stethoscope. The fingernails and toenails have started to develop completley and the skin is getting thicker. This marks the halfway point of pregnancy.
  • Week 21

    Week 21
    The fetus has grown to be 10.5 inches with 12.5 ounces because it is gaining weught steadily. Bone marrow has started to produce blood cells. The small intestine has started to absorb sugars.
  • Week 22

    Week 22
    The fetus is about 28 cm long. The fetus starts to have a normal waking and sleep rhythm and the taste buds have started to form on the tongue. The baby reacts to loud sounds outside of the womb.
  • Week 23

    Week 23
    The fetus measures up to 28cm and the eyebrows are now fully developed. The fetus can suck succesfully and a sense of balance occurs.
  • Week 24

    Week 24
    The fetus begins to gain 3 ounces a week and is about 12 inches long. This week is considered the viable stage if born.
  • Week 25

    Week 25
    The child is about 13.5 inches and weighs 1.5 pounds. Hands are fuly developed and the bones are hardening, The sexual organs are full developed as well
  • Week 26

    Week 26
    The fetus is 14 inches long and the eyes begin to open. Fetus respond to touch on the belly wall and sometimes interact.
  • Week 27

    Week 27
    The fetus is about 14.5 inches long and weighs almost 2.5 pounds. The baby will look much like it will after birth and the brain is still developing. This marks the start of the third trimester!
  • Week 28

    Week 28
    The hair on the head is visible now and brain waves can be recorded. The milk teeth have fully developed and the baby is able to move his or her eyes around.
  • Week 29

    Week 29
    The baby is about 2.5 pounds and is 15 inches. The muscles and lungs are still developing and the brain is producing nuerons. The fetus is also able to taste.
  • Week 30

    Week 30
    The fetus is about 16 inches and weighs about 3 pounds. The wrinkled skin becomes more smooth. If the fetus is a boy the testes move down and the baby controls his or her own body temperarture.
  • Week 31

    Week 31
    The fetus is 16.5 inches and their eyes are fully responsive to light. The respiratory system and al other major organs are close to being fully developed.
  • Week 32

    Week 32
    The fetus is about 17 inches and weighs about 4 pounds. Majority of the activities in the womb is sleeping and the fingernails and toenails are completley formed.
  • Week 33

    Week 33
    The fetus is about 17.5 inches and almost 5 pounds. The down that coated the body has started to disappear adn the fetus has started to practice breathing motions.
  • Week 34

    Week 34
    The fetus is about 18 inches long and weighs about 5.5 pounds. The fetus has an increased survival rate outside of the womb now and the fetal position may be positioned towards the birthing canal.
  • Week 35

    Week 35
    The fetus body is growing rounder and rounder due to the fat cells building up and the lungs are almost fully matured. If the baby was birthed there is a 90% survival rate but they may still be placed in an incubator
  • Week 36

    Week 36
    The fetus is about 19+ inches and weighs about 6 pounds. Mothers start to feel Braxton Hicks contractions.
  • Week 37

    Week 37
    The fetus is about 19 inches and weighs about 7 pounds. The water could break at anytime during this point.
  • Week 38

    Week 38
    The fetus is about 20 inches and may be in the final birthing position. Majority of the white substance covering their bodies has dissapeared.
  • Week 39

    Week 39
    The fetus remains the same size for the next week and same weight. While it is in its final birthing position the baby may move quite a bit under the pelvic bone.
  • Week 40

    Week 40
    Everything within in the fetus is fully developed and is ready to go. Labor has already started or will start with contractions. The baby could be born before of after this 40 week mark.