Fetal Development

A fetus is a developing human being with its own unique DNA that manages its development as it grows and changes rapidly through pregnancy. A typical pregnancy is 40 weeks long and has three trimesters which are each marked by distinct developments in each week.

Week 1
Last Menstrual Period

Week 2

Week 3
Baby attaches to the uterus

Week 4
Nerves, brain and spinal cord begin to develop

Week 5
Baby’s heart begins to beat

Week 6
Eyes, arms, legs, lungs, and stomach begin to form


Week 7
Hands and feet are forming

Week 8
Upper lip, teeth, fingers and ears begin to form

Week 9
Toes and genitals are forming

Week 10
Baby has permanent fingerprints


Week 11
Baby starts to produce urine

Week 12
Fingernails are forming

Week 13
Baby flexes and kicks

Week 14
Hormones gear up


Week 15
Skin begins to form

Week 16
Facial expressions are possible

Week 17
Fat accumulates

Week 18
Baby begins to hear


Week 19
  Lanugo covers baby’s skin

Week 20
The halfway point

Week 21
Nourishment evolves

Week 22
Taste buds develop


Week 23
Lungs prepare for life outside the womb

Week 24
Sense of balance develops

Week 25
Exploration continues

Week 26
Eyes remain closed


Week 27
Second trimester ends

Week 28
Baby’s eyes open

Week 29
  Movement is more forceful

Week 30
Baby packs on pounds


Week 31
Reproductive development continues

Week 32
Downy hair falls off

Week 33
Baby detects light

Week 34
Protective coating gets thicker

Week 35
Rapid growth continues

Week 36
Baby can suck

Week 37
Baby is full-term

Week 38
Organ function continues to improve

Week 39
Placenta provides antibodies

Week 40
Your due date arrives