Fetal Development Timeline: From Embryo to Newborn Senses

Fetal Development: The Journey to Birth

First Trimester Milestones (Weeks 8–11)

By 8 weeks, the embryo transitions into a fetus.

Week 9: Nervous System and Movement

• The nervous system generates neurons.
• The fetus begins to tremble, strengthening muscles through involuntary spasms.
• The brain does not yet control the heartbeat.

Week 11: Reflexes and Growth Spurt

• The kicking reflex begins (the fetus starts experimenting with its feet).
• The period from Week 6 to 11 shows the most notable growth.

Second Trimester Development (Up to Week 18)

The fetus develops strong muscles and bones, connecting all organs of the nervous system. It gains total control of the brain and becomes sensitive to touch. The fetus is aware of its space and performs countless movements.

Week 18: Digestion, Movement, and Sensory Input

• The digestive system begins to function.
• The mother starts to feel the baby's movements (quickening).
• The baby starts to blink.
• The fetus measures approximately 18 cm and has developed its unique fingerprint.

Note: Preterm infants tend to have impairments and learning difficulties.

Sensory Development in Utero

The fetus develops gustatory elements (taste experiences). Eyelashes and eye color appear, though the final color is not defined until after birth. The ear begins to perceive noise, but the neurons necessary for external listening develop later. The fetus must learn to suck and swallow.

If the mother is nervous or confused, these emotional states are transmitted to the fetus. The last organs to fully develop are the lungs.

Third Trimester and Preparation for Birth

Week 28: Sensory Activation and Memory

• A layer of fat is created (subcutaneous fat).
• All senses become active.
• The brain's cortex develops, allowing the fetus to obtain knowledge and form memories.
• The baby prepares for birth.
• Music listened to by the mother while pregnant is often remembered by the child after birth.

Week 33: Final Stage

This is the final stage of growth. Every movement of the fetus may become painful for the mother due to the maximum size achieved by the baby.

Week 38: Labor and Delivery

Labor begins when the amniotic sac (Amniotic) breaks.

The Newborn's Sensory World

Upon birth, the baby's senses are highly developed:

Hearing

The newborn is sensitive to the intensity of sound and is particularly interested in the human voice.

Vision

Vision is limited. The baby squints its eyelids when the image changes but does not distinguish light well. Perception improves significantly up to 3 months of age.

Taste

Taste is highly developed. Newborns prefer sweet flavors over sour, and they reject salty or bitter tastes.

Touch

Touch is the baby's primary language. Contact with the skin and warmth helps the baby capture the mother's vibrations.

Smell

The baby responds to smell with a grin when the scent is pleasant, or reacts negatively if the smell is very strong or unpleasant.