Fetal Development

Week 1 - Last Menstrual Period
Week 2 - Conception
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

Citation:  Mayo Clinic - Mayo Foundation for Medical Education and Research.
http://www.mayoclinic.com/health/fetal-development