Articles
Fetal development: The 1st trimester
Content
Weeks 1 and 2: Getting ready
Week 3: Fertilization
Week 4: Implantation
Week 5: Hormone levels increase
Week 6: The neural tube closes
Week 7: Baby's head develops
Week 8: Baby's nose forms
Week 9: Baby's toes appear
Week 10: Baby's elbows bend
Week 11: Baby's genitals develop
Week 12: Baby's fingernails form
Week 6: The neural tube closes
Growth is rapid this week. Just four weeks after conception, the neural tube along your baby's back is closing. The baby's brain and spinal cord will develop from the neural tube. The heart and other organs also are starting to form.
Structures necessary to the formation of the eyes and ears develop. Small buds appear that will soon become arms. Your baby's body begins to take on a C-shaped curvature.