Fetal Development

1
Fetal Development
2

• First trimestermonths 0-3
• Second Trimestermonths 4-6
• Third Trimestermonths 7-delivery

3
Week 2

• Embryo is about 1.5 millimeters long
• Neural plate appears

4
Week 3

• 2.3 millimeters long
• Has 12-14 somites (embryonic body segments)
• Blood vessels and primitive gut begin to develop
• Begins Most critical weeks of development

5
Week 4

• 5.2 millimeters long
• Increases mass 7,000 times
• Eyes begin forming
• Heart is still a tube but it begins to flutter
  and pulsate
• Neural groove closes
• Embryo is C-shaped
• Now has 30 pairs of somites
• Muscles, bones, and connective tissue develops
  from somites
• Arm buds are visible and leg buds begin to form
• By end of week 4, heart develops into four
  chambered vessel

6
Month 2

• Embryo increases in mass 500 times and weighs
  about 1/30 ounce (1 aspirin)
• About 1 inch long
• After 2 months, called a fetus
• Arms, legs, knees, elbows, fingers, and toes
  begin to form
• There is a temporary tail that is longest at this
  time but gradually disappears . Gone in 94 of
  babies by time of birth.
• Liver is now about 10 of body and is the main
  blood forming organ
• Diseases my effect development such as German
  measles which affects heart formation, the eye
  lens, the inner ear, and brain

7
Month 3

• Around 3 inches long from head to buttocks and
  weighs about ½ ounce (15 aspirins)
• Fetus is able to move arms and kick legs
• Has reflexes like squinting, frowning
• External sexual organs begin to develop
• Can suck and swallow some of the fluid that
  surround the amniotic sac
• Kidneys and the other excretory structures
  develop
• Waste is disposed thru placenta

8
Month 4

• 5 inches long (head to buttocks) and weighs 5
  ounces
• Bony skull is forming and can be seen by X-ray
• The body is becoming covered by protective,
  cheesy coating

9
Month 5

• 7 inches long and weighs ½ lbs. or 8 ounces
• Has hair on head
• Body is covered by fuzzy soft hair called lanugo
• Heart beats 120-160 times /minute
• Youngest child to survive was 23 weeks but
  required assisted breathing, feeding, temperature
  maintenence

10
Month 6

• 12-14 inches long and weighs 1.5 lbs.
• 90 of fetal weight gain occurs during this time
• At end of 6 months, a fetal typically has a good
  chance of survival
• Skin is red and wrinkled
• Abundant cheesy body covering
• Can now find pasty green mass of dead cells and
  bile called meconium in bowel which stays until
  birth
• Problem if released early, child is exposed to
  bacterial infection especially in lungs
• eyes and eyelashes appear

11
Months 7-9

• Doubles in size
• Many nerve tracts are forming and new brain cells
  are produced at rapid rates
• Protein intake by mother is important because
  protein is needed to develop the nervous system
  affecting intelligence
• At months 8-9 fat is deposited which smoothes out
  the wrinkles
• Nails project
• Hair coat sheds