This document outlines the stages of fetal development from weeks 0 to 38, detailing the formation of various body systems including the nervous, circulatory, respiratory, and digestive systems, as well as limb growth and sensory development. Key milestones include the development of the heart and circulatory system, formation of organs, and the establishment of senses such as hearing and sight. By week 38, the fetus is fully developed with functional organs and features characteristic of a newborn.

1. FETAL
DEVELOPMENT
ALLAN LLOYD M. MARTINEZ
ERAP A. PAAYAS

2. WEEK 0-8
NERVOUS SYSTEM:
Neutral plate forms & will develop into nervous
system (WEEK 3)
Brain forms and the rapid growth begins (WEEK 4)

3. WEEK 0-8
EYES, EARS & MOUTH:
Basic features of face such as eyes, ears and mouth
begin to form (WEEK 4)
Eyes have retina and lens (WEEK 5)
Teeth begin to form (WEEK 6)
Forehead and lenses of the eyes begin to form
(WEEK 7)

4. WEEK 0-8
HEART & CIRCULATORY SYSTEM:
Development of an embryo begins (WEEKS 1 and 2)
A tiny yolk sac supplies the embryo with nourishment from
the mother (WEEK 2)
The embryo begins to grow and develop (WEEKS 4 and 5)
The heart begins to beat (WEEK 4)
Liver starts to produce blood cells (WEEK 5)
Heart has almost completely formed (WEEK 8)

5. WEEK 0-8
LIMBS:
Hands begin to develop; nerves grow into limb buds
(WEEK 5)
Other parts include elbows, fingers, feet and toes begin
to develop and form (WEEKS 6-7)
Separation of fingers and toes happen (WEEK 8)

6. WEEK 0-8
RESPIRATORY SYSTEM:
Bronchial tubes start to form in the lungs (WEEK 4)

7. WEEK 0-8
DIGESTIVE SYSTEM:
A tube develops which will become intestines, liver,
pancreas and bladder (WEEK 3)
 Stomach also develops (WEEK 4)
Rapid growth of the liver begins (WEEK 5)

8. WEEK 0-8
SKELETAL & MUSCULAR SYSTEM:
Cartilages, joints and bones begin to form and
straighten; muscles for skeletal system also begin to
form (WEEKS 6 and 7)

9. WEEK 0-8
URINARY & GENITAL SYSTEMS:
Permanent kidneys begin to form (WEEK 5)
Testes and ovaries are distinguishable (WEEK 8)

10. WEEK 9-38
NERVOUS SYSTEM:
Basic divisions of the brain are complete (WEEK 10)
Spinal column forms (WEEK 23)
Brain’s neurons are formed; its activity for visual and
auditory systems begins (WEEK 24)
Fetus is sensitive to its 5 senses (WEEK 27)
Hearing is at fully developed stage (WEEK 35)
Increased central nervous systems control over body
functions (WEEK 36)

11. WEEK 9-38
EYES, EARS & MOUTH:
 Lenses of the eye begins to form; palate begins to fuse (WEEK 9)
 Vocal cords form (WEEK 11)
 Completion of palate fusion happens (WEEK 12)
 Eyes & ears are almost in their final positions (WEEK 14)
 Eyelids are formed and fused shut (WEEK 20)
 Middle ear bones begin to harden (WEEK 21)
 Fetus can open its eyes (WEEK 26)
 Baby begins to blink and can determine light and dark (WEEK 34)
 Hair grows to the baby (WEEK 37)

12. WEEK 9-38
HEART & CIRCULATORY SYSTEM:
Placenta functions completely (WEEK 9)
Heart begins to pump blood (WEEK 15)
Heart is fully developed (WEEK 38)

13. WEEK 9-38
LIMBS:
Hands can be functional (WEEK 12)
Fetus begin to store fats (WEEK 15)
Pads form on fingertips & toes (WEEK 16)
Fingernails are formed completely (WEEK 32)

14. WEEK 9-38
DIGESTIVE SYSTEM:
Insulin is secreted from the pancreas (WEEK 10)
Intestines have moved from umbilical cord to
stomach (WEEK 11)
Bile is secreted from the liver (WEEK 12)
Liver begins to produce waste products (WEEK 35)

15. RESPIRATORY SYSTEM:
Breathing movement from the lungs begins (WEEK
9)
Air sacs in the lungs develop and has good blood
flow (WEEK 24)
Lungs are developed completely (WEEK 35)
WEEK 9-38

16. WEEK 9-38
SKELETAL & MUSCULAR SYSTEMS:
Increase of connections between nerves & muscles
(WEEK 10)
Red blood cells are produced by the bone marrow
(WEEK 28)
Hardening of bones happened; skull is still pliable
and not completely joined (WEEK 33)

17. WEEK 9-38
URINARY & GENITAL SYSTEMS:
Kidneys are functioning (WEEK 9)
Genitalia are now fully developed within the baby’s
body; a penis or clitoris will begin to form externally
(WEEK 13)
Baby is starting to form urine (WEEK 13)
Development of uterus happens (WEEK 20)
Testes begin to descend to scrotum (WEEK 28)
Kidneys are fully developed (WEEK 35)