Students for Life of America

 

Links on Fetal Development

Just the Facts is an interactive website that shows visitors how babies develop in the womb through pictures and videos. The site also has teaching resources available.

Windows to the Womb by Life Issues Institute presents 19 high quality images of unborn babies. Each of the photographs are available for sale on a CD.

Science for Unborn Human Life has hundreds of facts about the rapid development of the unborn child’s body, movements, sensations (including pain) and learning, with each fact accompanied by a reference to the scientific or medical literature. The accuracy of the information is endorsed by eight OBGYNs.

Books on Fetal Development

A Child is Born – Lennart Nilsson

Life – Lennart Nilsson

From Conception to Birth: a Life Unfolds - Alexander Tsiaras

Videos on Fetal Development

In the Womb - National Geographic

In the Womb Multiples - National Geographic

From Conception to Birth - Discovery Channel

Milestones of Fetal Development

Weeks 1-4

• Conception occurs when the sperm fertilizes the egg.
• Gender is determined by the sperm which carries both an X and a Y chromosome.
• The embryo implants itself on the wall of the uterus.
• A neural tube forms. (This is the foundation that will develop into the nervous system).
• The heart and primitive circulatory system rapidly form.

 

Week 5

• The heart begins to form and beat during this week.
• The umbilical cord develops.
• Lungs, intestines, and the beginnings of the urinary system form.
• The beginnings of arms and legs start appearing.

Week 6

• The neural tube closes this week.
• Arms and legs continue to develop.
• Facial features start forming, and nostrils are distinct.
• Lenses on the eyes appear.
• Vital organs are continuing to form, including the kidneys, liver, pancreas, lungs, stomach, and intestines.
  

Week 7

• The mouth has started to develop, and small indentations are appearing where the ears will develop.
• Teeth buds are beginning to develop.
• More distinct eyes are developing along with pigmented irises.
• The heart is beating very quickly now (about 150 beats per minute).
• Feet begin to have tiny notches that will become toes.

Week 8

• Cartilage and bones begin to form, as well as the ribcage.
• Intestines move out of the umbilical cord and into the abdomen.
• Blood is beginning to flow through the rudimentary circulatory system.
• Elbows are appearing.
• Fingers and toes are webbed and short but continuing to grow.

Week 9

• The head is now much larger than the rest of the body.
• The baby begins to move, though still too small for the mother to feel.
• Development of inner and outer ears is completing.
• Fingerprints are beginning to appear and the baby is experiencing first nerve connections in the brain.

Week 10

• Taste buds are beginning to appear on the tongue.
• Eyelids are almost closed (and won’t open until the 27th week).
• Reproductive organs and genitals are forming.
• Because of brain development, the head is half the length of the body.
• The upper lip is formed completely.

Week 11

• All major organs are becoming fully developed.
• Bones are beginning to solidify.
• Fingers and toes have separated.
• Amniotic fluid begins to accumulate while the kidneys start functioning.
• The baby is starting to swallow and kick.
• A period of rapid growth has begun.

Week 12

• Ears are shifting to their normal places.
• Vocal cords are developing.
• The pancreas begins to produce insulin.
• Intestines move farther into the body.
• Brain mass continues to grow, and brain structure is now intact.
• Non-pigmented hair (called lanugo) begins to appear on the body.

Week 13

• Tissues and organs are continuing to mature.
• Bone marrow, liver, and spleen are now able to produce blood cells.
• The neck lengthens and the head no longer rests on the chest.
• The hands are becoming functional.

Week 14

• The baby is beginning to practice breathing movements.
• In males, the prostate gland develops.
• In females, the ovaries move from the abdomen to the pelvis.
• The thyroid continues to mature, producing growth hormones

Week 15

• Eyes and ears are moving into their final positions.
• The baby may start sucking his/her thumb.
• The legs have now grown longer than the arms.
• Hair on the head and eyebrows are beginning to appear.

Week 16

• The baby begins to make facial expressions due to developed facial muscles.
• The head and neck are held upright.
• The baby may get hiccups though the mother still will not be able to feel them.
• The heart is now pumping the equivalent of 25 quarts of blood per day.
• The baby is beginning to develop a sensitivity to light.

Week 17

• Layers of fat are beginning to form to provide insulation for the baby.
• The umbilical cord is becoming stronger and thicker.
• The skeleton is slowly turning from cartilage to bone.
• Meconium (made up of products of cell loss, digestive secretion, and swallowed amniotic fluid) is accumulating in the bowel.

Week 18

• Vernix forms on the skin to protect it during the months in water.
• The vocal chords are formed.
• The bones in the inner ear and nerve endings in the brain have developed enough that sounds will begin to be detected.
• If a female, the vagina, uterus, and fallopian tubes will be in place by the end of the week.
• Features of the heart, including ventricles and chambers, will be visible on an ultrasound.
• Alveoli begin to form in the lungs.

Week 19

• Buds that will produce permanent teeth are now forming behind the baby teeth buds.
• Hair on the scalp becomes apparent this week.
• The nerves are being coated by a substance called myelin which insulates the nerves so that impulses can flow smoothly.

Week 20

• The skin is developing into three layers: the dermis, epidermis and subcutaneous layers.
• The heartbeat is growing stronger.
• Immunities are being transferred from mother to child to protect the baby after birth.
• Hair and fingernails are continuing to grow.

Week 21

• Legs are reaching their correct proportions.
• The brain is growing very quickly, although the general growth pattern has slowed.
• The heart continues to get stronger as other organs mature.
• The tongue is fully formed.
• Wake and sleep periods are more consistent.

Week 22

• Eyelids and eyebrows are fully formed.
• Distinct lips will be formed.
• Fingernails will grow to the end of the fingertips.
• If a male, testes will begin to descend into the scrotum, and primitive sperm will be formed.
• The liver is starting to break down bilirubin (with some assistance from the mother).

Week 23

• Pigment is deposited this week to create skin tone.
• The pancreas is developing steadily.
• The bones in the middle ear harden.

Week 24

• The lungs begin to produce surfactant – a substance that assists in breathing and keeps the lungs from collapsing.
• Taste buds begin to form.
• Sweat glands are starting to form on the skin.
• Coordination improves, and the baby will start exploring the his/her environment.

Week 25

• Nerves around the mouth are becoming more sensitive in preparation for nursing.
• Dexterity continues to develop.
• The structures of the spine begin to form.
• The nostrils are beginning to open.

Week 26

• The spine is gaining strength and becoming more supple.
• Eyelashes are beginning to grow.
• The baby’s eyes may begin to blink and open.
  
• Retinas begin to form.

Week 27

• The eyes, which have been fused closed, finally open.
• The immune system is still developing, along with the lungs and liver.
• The response to sound becomes more consistent.
• The brain continues to grow and develop rapidly.

Week 28

• Layers of fat are continuing to be added underneath the skin.
• Hair is continuing to grow.
• Muscle tone is improving.
• Lungs are now capable of breathing air.

Week 29

• The baby will start kicking as the muscles develop.
• Lanuga hair on the body will begin to disappear.
• Body fat is accumulating.
• The skeleton is continuing to harden.
• The lungs are continuing to mature.

Week 30

• Hearing development is such that the baby can now detect sound.
• The head is growing larger to accommodate rapid brain growth.
• The baby is now capable of creating tears.
• The eyes can move side to side following a light source.

Week 31

• The eyes will now be open when the baby is awake and closed when he/she is sleeping.
• The eyes will also develop pigment at this stage.
• The baby may begin to move to music as he/she reacts to sound.
• The lungs are the last major organ still developing

Week 32

• Fingernails and toenails should be completely formed.
• As the lanuga hair is dropping off, the hair on the scalp grows more quickly.
• The baby may begin to dream in REM sleep.
• The head is now capable of moving from side to side.

Week 33

• The amniotic fluid is at its highest level.
• Neurons and synapses in the brain are developing in great numbers.
• The head will increase by about 3/8 of an inch.
• If a male, the testicles with by descending from the abdomen to the scrotum.
• The skull is still pliable, in preparation for birth.
• The baby is now sleeping most of the time.

Week 34

• The baby is learning to blink.
• The vernix coating on the skin is getting thicker.
• The adrenal glands are growing and producing corticoid hormones that will help stimulate lactation.
• Antibodies from the mother are being transferred to the baby to help with immunity.
• The baby may be transitioning to a head-down position in preparation for birth.

Week 35

• The central nervous system is maturing.
• The lungs should be almost fully developed.
• Accumulated fat (brown fat) will begin to plump up the arms and legs.
• Hearing is fully developed.

Week 36

• Lungs are in their final stages of development.
• Major organ development is complete.
• Fat is continuing to accumulate.
• The gums in the mouth are now rigid.
• The baby may move into the birth canal this week.

Week 37

• Dexterity in the fingers is improving.
• The baby is developing definite activity cycles.
• The baby will now turn towards the light.
• The immune system is strengthening.

Week 38

• A good amount of meconium is accumulating in the intestines.
• The circumference of the baby’s head and abdomen are now about the same.
• Fat and hair are still accumulating.

Week 39

• The baby now has over 300 bones as the skeleton continues to develop.
• The lungs are maturing and producing more surfactant.
• The body continues to create fat to insulate the baby.

Week 40

• The lungs will continue to develop until birth.
• After birth, most of the vernix will be gone, though some traces may still be noticeable.
• The head may be cone-shaped after birth due to the passage through the birth canal, but will become round again in the next few days.
• The baby will be capable of crying at birth, though tears may not appear because of underdeveloped tear ducts.

Citations:Images borrowed from www.pregnancy.org .

Information from www.pregnancy.org and www.verybestbaby.com.

© Students for Life of America 2007